General

JERG-0-001F(E)(A Revised Edition)

TECHNICAL STANDARD
FOR
HIGH-PRESSURE GAS EQUIPMENT FOR SPACE USE

February 8, 2022

JAPAN AEROSPACE EXPLORATION AGENCYT his is a n E n g lis h tr a n s l at i on of J E RG - 0- 00 1 F, “T E C HN IC A L ST A N DA RD FO R HI G H PR E S S UR E G A S EQ U IP M E NT FO R S P AC E US E ,” a nd do es n ot c o ns t i tu te its e lf .
W hene ve r t h is d oc um ent c o nf l ic ts wi t h th e or i gi n a l doc um en t i n J a p an es e, t h e or ig i n al
doc um en t tak es pr ec e de nc e.

Dis c l a im er
T he i nf orm at io n c o nt a i ne d h er e i n is f or g e ner a l i nf orm at i on a l p u rpos es o n l y. J AX A
m ak es no war r a nt y, e x pr es s or im pl i ed , i nc l ud i ng as t o t h e ac c u rac y, us ef ul n es s or
tim e li n es s of a n y inf or m atio n h er e i n. J AX A wi l l n ot b e li a b le f or a n y los s es r e l at i ng t o
th e us e of t h e i nf or m at i on .

P ub l is he d b y
J ap a n A er os p ac e Ex p l or a t io n Ag e nc y
S af et y a n d M is s io n As s ur a nc e D ep artm e nt
2- 1 - 1 Se n ge n T s uk ub a - s h i, I ba r ak i 3 0 5 - 8 5 05 , J a p an

CONTENTS
1.

General ---------------------------------------------------------------------------------------------------------------- 1
1.1 Purpose --------------------------------------------------------------------------------------------- 1
1.2 Scope ------------------------------------------------------------------------------------------------ 1
1.3 Measurement Unit -------------------------------------------------------------------------------- 2
1.4 Related Documents ------------------------------------------------------------------------------ 2
1.4.1 Applicable documents .................................................................................. 2
1.4.2 Reference documents .................................................................................. 3
1.5 Definition of Terms ------------------------------------------------------------------------------- 8

2.

Design and Fabrication Procedure for High-Pressure Gas Equipment for Space

Use-------------------------------------------------------------------------------------------------------------------------------------16

2.1 Development Flow ------------------------------------------------------------------------------ 16
2.1.1 Design ....................................................................................................... 16
2.1.2 Qualification test ........................................................................................ 17
2.1.3 Flight model fabrication .............................................................................. 17
2.2 Exemption Provision --------------------------------------------------------------------------- 17
2.2.1 High-pressure gas equipment of safety factor 4 or more .............................. 17
2.2.2 High-pressure gas equipment that have been qualified ............................... 18
2.2.3 Purchased item .......................................................................................... 19
2.2.4 High-pressure gas equipment for space use certified as conforming to othertechnical standards ............................................................................................ 20
2.3 Special Treatment ------------------------------------------------------------------------------ 21
3.

Design ---------------------------------------------------------------------------------------------------------------- 23
3.1 Setting of Design Conditions ----------------------------------------------------------------- 23
3.1.1 Function and performance requirements ..................................................... 23
3.1.2 Load and temperature conditions................................................................ 23
3.1.2.1 Maximum Expected Operating Pressure (Limit pressure) ...................... 23
3.1.2.2 Load during flight ................................................................................ 25
3.1.2.3 Load during ground handling ................................................................ 26
3.1.2.4 Temperature condition ......................................................................... 27
3.1.3 Safety factor .............................................................................................. 29
3.1.3.1 Safety factor for pressure .................................................................... 29
3.1.3.2 Safety factor for flight load ................................................................... 30
3.1.3.3 Safety factor for buckling ..................................................................... 32
3.1.3.4 Safety factor for ground handling (only for launch vehicle propellant tanks)...................................................................................................................... 32
3.1.4 Interface requirements ............................................................................... 32
3.1.5 Life requirements ....................................................................................... 32i3.2 Structure Type Setting ------------------------------------------------------------------------- 34
3.2.1 Structure type of metallic pressure vessel................................................... 34
3.2.2 Structure type of launch vehicle propellant tank .......................................... 34
3.2.3 Structure type of COPV .............................................................................. 34
3.3 Material Selection ------------------------------------------------------------------------------ 41
3.3.1 Mechanical property ................................................................................... 41
3.3.2 Fracture property ....................................................................................... 41
3.3.3 Compatibility .............................................................................................. 42
3.3.4 Fabricability ............................................................................................... 43
3.4 Thickness Calculation ------------------------------------------------------------------------- 44
3.4.1 Thickness calculation for metallic pressure vessel ...................................... 44
3.4.1.1 Thickness of cylindrical shell plate ....................................................... 44
3.4.1.2 Thickness of spherical shell plate ........................................................ 45
3.4.1.3 Thickness of conical shell plate ........................................................... 45
3.4.1.4 Thickness of torispherical head plate or total hemispherical head plat e . 45
3.4.1.5 Thickness of semi-ellipsoidal head plate .............................................. 45
3.4.1.6 Thickness of conical head plate ........................................................... 46
3.4.2 Calculation of plate thickness of launch vehicle propellant tank ................... 47
3.4.2.1 Cylindrical shell ................................................................................... 47
3.4.2.2 Head (Dome part) ................................................................................ 50
3.4.3 Calculation of plate thickness of COPV ....................................................... 54
3.4.3.1 Calculation of plate thickness .............................................................. 54
3.4.3.2 Confirming compressive strength of a metallic liner .............................. 58
3.4.3.3 Confirming buckling strength of the metallic liner .................................. 58
3.4.3.4 Drawing pressure-strain diagram ......................................................... 59
3.5 Detailed Analysis ------------------------------------------------------------------------------- 64
3.5.1 Stress analysis .......................................................................................... 66
3.5.1.1 Pressure analysis ................................................................................ 66
3.5.1.2 Analyses for flight ................................................................................ 69
3.5.1.3 Analyses for ground handling ............................................................... 70
3.5.1.4 Judgment criteria ................................................................................. 71
3.5.2 Judgment of LBB occurrence (Analysis and testing) .................................... 79
3.5.2.1 Judgment of LBB occurrence by analysis ............................................. 79
3.5.2.2 Judgment of LBB occurrence by test .................................................... 88
3.5.3 Fatigue damage analysis and test .............................................................. 93
3.5.3.1 Fatigue damage analysis ..................................................................... 93
3.5.3.2 Fatigue damage test ............................................................................ 96
3.5.4 Flaw growth analysis and test .................................................................... 97ii

3.5.4.1 Flaw growth analysis ........................................................................... 97
3.5.4.2 Flaw growth test ................................................................................ 103
3.5.5 Stiffness analysis and test ....................................................................... 104
3.5.6 Bellows analysis ...................................................................................... 104
3.5.6.1 Stress analysis and judgment criteria ................................................. 104
3.5.6.2 Life analysis and judgment criteria ..................................................... 104
3.5.6.3 Fluid vibration ................................................................................... 104
3.5.6.4 Restriction of Bellows ........................................................................ 105
3.6 Damage Control Requirements for COPV ------------------------------------------------ 106
3.6.1 Damage pre ven tion con trol ................................................................... 106
3.6.1.1 Development of damage prevention control plan ................................. 106
3.6.1.2 Compliance with the damage prevention control plan and record of d amage
prevention control ......................................................................................... 107
3.6.1.3 Detection and judgment of damage .................................................... 107
3.6.2 Damage tolerant design ........................................................................... 107
3.6.3 Consideration to damage control .............................................................. 108
4.

Fabrication ------------------------------------------------------------------------------------------------------- 110
4.1 Fabrication and Forming --------------------------------------------------------------------- 110
4.2 Welding ------------------------------------------------------------------------------------------ 110
4.2.1 General requirements .............................................................................. 110
4.2.2 Welding control ........................................................................................ 111
4.3 Heat Treatment --------------------------------------------------------------------------------- 118
4.4 Non-metallic Liner Forming ------------------------------------------------------------------ 118
4.5 Filament Winding ------------------------------------------------------------------------------ 118
4.6 Autofrettage ------------------------------------------------------------------------------------- 118
4.7 Inspection and Test --------------------------------------------------------------------------- 119
4.7.1 Material acceptance inspection ................................................................ 119
4.7.1.1 Metallic material acceptance inspection ............................................. 119
4.7.1.2 Composite material acceptance inspection ......................................... 119
4.7.1.3 Non-metallic liner acceptance inspection ............................................ 120
4.7.2 Parts inspection (Metallic material) ........................................................... 120
4.7.3 Welded part inspection ............................................................................. 121
4.7.3.1 Welding condition .............................................................................. 121
4.7.3.2 Visual inspection ............................................................................... 121
4.7.3.3 Welding deformation and mis-match ................................................... 121
4.7.3.4 Welding bead and penetration bead ................................................... 121
4.7.3.5 Weld defect ....................................................................................... 122
4.7.4 Acceptance inspection ............................................................................. 124iii

4.7.5 Acceptance test ....................................................................................... 125
4.7.5.1 Metallic high-pressure gas equipment acceptance test ....................... 125
4.7.5.2 COPV acceptance test ....................................................................... 127
5.

Development Test and Qualification Test ----------------------------------------------------- 132
5.1 Development Test ----------------------------------------------------------------------------- 132
5.1.1 Material basic test ................................................................................... 132
5.1.2 Welding method selection and verification ................................................ 133
5.1.3 Prototype test .......................................................................................... 133
5.2 Qualification Test ------------------------------------------------------------------------------ 134

6.

Reuse --------------------------------------------------------------------------------------------------------------- 138
6.1 Reuse Inspection ------------------------------------------------------------------------------ 138
6.1.1 Visual inspection ..................................................................................... 138
6.1.2 Nondestructive inspection ........................................................................ 138
6.1.3 Dimension inspection ............................................................................... 138
6.2 Reuse Test -------------------------------------------------------------------------------------- 139
6.3 Repair -------------------------------------------------------------------------------------------- 139

7.

Safety Assurance During Pressurization ----------------------------------------- 141

8.

Handling --------------------------------------------------------------------------------- 143

9.

Measures for Revisions -------------------------------------------------------------- 144

APPENDIX ------------------------------------------------------------------------------------ 145iv

1. General
1.1 Purpose
This technical standard provides technical standard of high-pressure gas equipment
installed in launch vehicle and payload developed or launched by Japan Aerospace
Exploration Agency (JAXA).
1.2 ScopeThis technical standard shall apply to the following high-pressure gas equipment(including purchased item) which is installed in unmanned launch vehicle andpayload. High temperature condition which causes creeping problem of material isout of scope in this standard.
The scope of this standard is depicted in Table 1.2-1. The equipment that should beapplied to Minister of Economy, Trade and Industry in accordance with HighPressure Gas Safety Act for special approval of technical standard or license of
special filling (hereafter referred to as applied equipment) are illustrated in Figure
1-1 for reference.

Table 1.2-1 Scope of This Technical Standard
Disposable
equipment

Reusableequipment

No

Classification

1

Metallic pressure
vessel installed inlaunch vehicle andpayloadApplicable

Applicable

Gas reservoir,
propellant tank, heatpipe, and pressure
vessel for Ni-H 2
battery2

Composite
overwrapped pressure
vessel (COPV) installedin launch vehicle andpayloadApplicable

Applicable

Gas reservoir, andpropellant tank3

Propellant tank forlaunch vehicle(Metallic)

Applicable

Applicable

4

Propellant tank forlaunch vehicle (COPV)

NotapplicableNot applicable

5

Pressure piping, fitting,bellows, and othercomponents

Applicable

Applicable(individual
correspondence)

1

Note

1.3 Measurement Unit
This technical standard shall not provide unit of symbol in equation, unlessotherwise specified. When it is necessary for calculation, however, SI basic unit (m[length], kg [Mass], s [Time], etc.) and derived units (N [force], Pa [Pressure andStress], etc.) shall be used. If unit other than SI basic unit is used, coefficient shallbe used for conversion.
1.4 Related Documents
Unless otherwise specified, the latest issue of the following documents shall beapplied. When these documents conflict with this technical standard, this technicalstandard shall have precedence.
1.4.1 Applicable documents(1)

MMPDS-01

Metallic Materials Properties Development andStandardization(2)

AFML-TR-68-115

Aerospace Structural Metals Handbook(3)

AMS2645

Fluorescent Penetrant Inspection(4)

ASTM-E1742

Standard Practice for Radiographic Examination(5)

MIL-STD-889

Dissimilar Metals(6)

AWS D17.1

Specification for Fusion Welding of Aerospace
Applications(7)

ASTM-E1417

Standard Practice for Liquid Penetrant Examination(8)

SAE-AMS-STD-2154

Inspection, Ultrasonic, Wrought Metals, Process For(9)

JMR-001

System Safety Standards (JAXA Document)(10) JMR-002

Launch Vehicle Payloads Safety Standards (JAXA
Document)(11) SE-019-094-2H

Material Selection List and Use Instruction SRB/SRM(NASA Document)(12) Metallic Materials Specification Handbook (Federal Specification)(13) JIS B 8266Annex 8(Normative) Stress and Fatigue Analyses for
Pressure Vessels(14) NASA-CR 124075

Isogrid Design Handbook(15) NASA-CR 912

Shell Analysis Manual(16) ASTM D 2290

Standard test method for apparent tensile strength ofring or tubular plastics and reinforced by split disk2

method(17) ASTM D 3039

Standard test method for tensile properties of fiber
resin composite(18) JIS-K-6251

Vulcanized rubber and thermoplastic rubber - Methodof obtaining tensile properties(19) JIS B 8265

Annex N (Normative) “expansion joints of pressure
vessels”(20) ISO14623

Space Systems - Pressure Vessels and Pressurized
Structure - Safe Design and Operation(21) NDIS 3414

Method of Visual Testing (The Japanese Society for
Non-Destructive Inspection Standard)(22) NAS 1514

Radiographic Standard for Classification of Fusion
Weld Discontinuities(23) ASTM-E164

Standard Practice for Contact Ultrasonic Testing of
weldments
Special Treatment Method for Technical Standards
Conformity Examinations of High-Pressure Gas
Equipment for Space UseStandard Test Method for Short-Beam Strength ofPolymer Matrix Composite Materials and Their
Laminates
Testing Method for Apparent Interlaminar Shear
Strength of Carbon Fiber Reinforced Plastics byThree Point Loading Method
Fiber-Reinforced Plastics: Determining Apparent
Interlaminar Shear Strength by the Short-BeamMethodStandard for ultra-high pressure gas equipment (inJapanese)(24) CSA-115016(25) ASTM-D2344(26) JIS K 7078

(27) JIS K 7057

(28) KHKS 0220(2020)

1.4.2 Reference documents(1)

CSA-113004

Design Criteria for Metallic Pressure Vessels (JAXA
Document)(2)

MIL-STD-1522A

Standard General Requirements for Safe Design andOperation of Pressurized Missile and Space Systems(3)

CR 68815

JAXA Glossary of Space Related Terms(4)

JIS B 0190

Glossary of Terms Used for Structure of Pressure
Vessels3

(5)NASA SP-8040

Fracture Control of Metallic Pressure Vessels(6)

JIS B 8285

Welding Procedure Qualification Tests for Pressure
Vessels(7)

Mechanical Design Handbook (MARUZEN), edited by the Mechanical Design
Handbook Editorial Committee of Japan(8)

Glossary of Technical Terms in Welding and Jointing (SANPO PUBLISHINGCO.), edited by the Japan Welding Society(9)

JMR-006

Configuration Management Standard (JAXA
Document)(10) JMR-004

Reliability Program Standard (JAXA Document)(11) JMR-005

Quality Assurance Program Standard (JAXA
Document)(12) Aeronautical and Space Sciences Engineering Handbook (MARUZEN), editedby the Japan Society for Aeronautical and Space
Sciences(13) NASA TN D-8008

Outgassing Data for Spacecraft Materials(14) MRN89-441

Out-gassing Data for Organic Materials for SpaceUse(15) AIAA-83-1274

High-performance Prestressed Composite Tanks forSpace Use(16) NASA-CR-72753

Development of a Filament-overwrapped Cryoformed
Metal Pressure Vessel(17) NASA-CR-72124

Computer Program for the Analysis of Filamentreinforced Metal-shell Pressure Vessels(18) Bulletin of the Institute of Space and Aeronautical Science, University ofTokyo, Vol. 15, No. 4, “Developmental Research on
Carbon-Fiber-Reinforced Plastic Rocket Motor Case”(19) JERG-0-003

Technical Standard for High-Pressure Gas equipment
for Space Use Handbook (JAXA document)(20) “Reinforced Plastics Handbook” edited by the Reinforced Plastics Association,
Nikkan Kougyou Weekly(21) JEAG 4224-2009

Technical guidance of plant equipment diagnosis of
the nuclear power plant - Radiation wall thickness
diagnosis technology(22) CSA-114011

Conformity evaluation of high-pressure gas
equipment for space use (JAXA Document)(23) JIS B 8265
(24) JIS B 8267

Construction of pressure vessel - General principles
Construction of pressure vessel4(25) JIS B 8265
(26) JIS B 8210
(27) CAS-2018006A(28) JIS B 8277

Annex T (Normative) “Allowable pressure confirmation
testing”
Safety devices for protection against excessive
pressure – Safety valves
Procedures related to conformity assessment of highpressure gas equipment for space use (JAXA
document)
Expansion joint for pressure vessel

5Flange

Cryogenic GasReservoir

Launch Vehicle
Propellant Tank

Gas Jet Equipment
Propellant Tank

Normal Temperature
Gas Resevoir

FlangeNote 1) Solid line indicates within the scope.
Note 2) Dotted line indicates out of the scope.

Figure 1-1 (1/2) Applied Equipment Installed in Launch Vehicles (Example)

6

Pressure Vessel of Ni-H 2 Battery

Gas Reservoir

ValvesPropellant Tank

Heat Pipe

PayloadNote 1) Solid line indicates within the scope.
Note 2) Necessity of application of Heat Pipe and application of Pressure Vessel of NiH2 Battery depends on the equipment design specification.

Figure 1-1 (2/2) Applied Equipment Installed in Payloads (Example)

7

1.5 Definition of Terms
The terms used in this standard are defined as follows.
Acceptance Test
Acceptance test is the official test conducted for flight hardware to ascertain thatthe hardware is acceptable for delivery. This test is conducted to confirm whether
any defects exist in materials or fabricating processes of the hardware fabricatedaccording to the approved design.
Allowable Stress
Allowable stress is the limit of stress allowed in design, and differs according to
the type and division of stress. It is usually expressed as multiples of basic
allowable stress.
Autofrettage
Autofrettage is a pressurization process performed after composite materials areformed to expand the elastic deformation range of a metallic liner for COPV
operation.
Basic Allowable Stress
Basic allowable stress is the value of tensile stress used as the basis of allowab lestress specified by characteristics of material and temperature.
Backing
Backing is a metallic plate, tape or flux, which is attached to the bottom of a groovefrom the back.
Bending Stress
Bending stress is a component of primary stress that is proport ional to the distancefrom the centroid of a cross-section. It excludes structural discontinuities andstress concentration and is limited to stress generated by mechanical loads.
Buckling strength
Buckling, or buckling load, divided by the buckling safety factor.
Buckling stressStress arising in a structural member just before it buckles due to an external force.
Buckling load
Load applied to a structural member just before it reaches a buckled state due toan external force.
Burst Pressure

8Burst pressure is the pressure applied to high-pressure gas equipment when
actually bursted.
Burst Pressure Test
The burst pressure test is a test to confirm that high-pressure gas equipment does
not burst when design burst pressure is applied.
Burst Test
The burst test is a test to apply pressure to high pressure equipment until it burst.
Composite Material
Composite material is fiber reinforced plastics composing surface layer of the
COPV.
Composite Overwrapped Pressure Vessel (COPV)COPV is a pressure vessel which is composed with liner (inner layer) andcomposite material (surface layer).
Cylindrical Composite Overwrapped Pressure Vessel
A cylindrical composite overwrapped pressure vessel is a cylindrical pressure
vessel which is composed with liner and filament winding composite material.
Damage Control
An act of control executed to prevent deterioration of COPV’s fracture strength
below its functional requirements due to mechanical damage.
Damage Prevention Control
Consisting of administrative and control activities to prevent damage, developmentof a damage prevention control plan, compliance with the plan, and creation andmaintenance of damage prevention control record
Damage Tolerant Design
Design that will not lead to a fracture due to a damage, a crack, a peel, an impact
or other mechanical damage within a specific period of time, when such damage
is not repaired.
Design Burst Pressure
For metallic high-pressure gas equipment, design burst pressure is the product of
the MEOP and the safety factor for tensile strength. For COPV, it is the product of
the MEOP and the safety factor for design burst pressure.
Design Temperature
Design temperature is provided as a preset condition in a range of temperatureused by high-pressure gas equipment.

9FiberFiber is a primary reinforcing component for composite materials. It may be a glass
fiber, aramid fiber, or carbon fiber.
Filament Winding
Filament winding is the process of winding a fiber impregnated with matrix resinon the outer surface of a liner.
Flux
Flux is a material used to remove impurities, including oxide, from base materials
and filler materials; to protect the surfaces of base materials; or to refine weld
metals during welding and brazing.
Gas Reservoir
A gas reservoir is a container used to store high-pressure gas.
General Primary Membrane Stress
General primary membrane stress is membrane stress generated by pressure orother mechanical load, in structures having no discontinuous part in general andlocal construction.
GrooveA groove is a channel or furrow-like space provided in the base metals or between
base metals to be welded.
Hazardous Leakage
A hazardous leakage is a leakage of poisonous gas (N 2 H 4 , MMH, or NTO), or aleakage which results in a hazard such as breakage of external sections of highpressure gas equipment caused by a pressure increase due to leakage.
Helical Winding
Helical winding is a method of winding a fiber helically by filament windi ng.
High-Pressure Gas Equipment
High-pressure gas equipment is the equipment which operates high-pressure gas
defined in the High-Pressure Gas Safety Law Article 2.
Hoop Winding
Hoop winding is a method of winding a fiber on the cylindrical part by filamen t
winding. It is also called circumferential winding.
In-plane Winding
In-plane winding is a fiber winding method in which filament winding is performed

10

for a spherical liner. A fiber is wound along a plane passing through the center ofarticle. The plane is continuously shifted so the whole article is overwrapped withthe composite.
Launch Vehicle Propellant Tank
The launch vehicle propellant tank is a propellant tank that receives structuralloads as a part of the airframe of a launch vehicle.
Leak-Before-Burst (LBB)
LBB is a fracture mechanism design concept in which it is shown that any initialflaw will grow through the wall of high-pressure gas equipment and cause leakage
rather than burst.
Leak Test
The leak test is a gas leak test conducted at a pressure not less than the MEOP.
Limit Pressure
Limit pressure is the maximum pressure expected to be applied to the propellant
tanks in the operational environment.
Limit Load
Limit load is the maximum load of complex or single load applied in the operation.
Local Membrane Stress
Local membrane stress is the average of membrane stress at any cross -section.
Construction discontinuity is considered, but stress concentration is excluded. Only
membrane stress generated by mechanical loads is considered.
Local Primary Membrane Stress
Local primary membrane stress is membrane stress generated by pressure or othermechanical load, which becomes large locally due to influence of discontinuity andthe like of construction. The membrane stress has secondary st ress characteristics
but causes large distortion in other parts of construction.
Matrix Resin
A matrix resin fixes a fiber during composite materials forming. It may be
impregnated into a fiber beforehand or at the time of forming.
Maximum Expected Operating Pressure (MEOP)
The MEOP is the maximum expected pressure at which high-pressure gas
equipment will actually operate.
Metallic Liner
A metallic liner is metallic hardware that forms the inner layer of a COPV.

11

Mill Sheet
A Mill sheet is a data sheet developed by a material manufacturer which describes
information including test results, fabricated date, order dimensions, quantities,
and identification number for tracing the fabricating process from melting to product.
Material test report.
Mises Equivalent Stress
Mises equivalent stress is quantity which evaluates whether an object under three
dimensional stress is yielding or not and is expressed by the equation below.
σ e =[1/2×{(σ 1 −σ 2 ) 2 +(σ 2 −σ 3 ) 2 +(σ 3 −σ 1 ) 2 }] 1/2
where σ 1 , σ 2 , σ 3 : principal stressMis-match
Mis-match is the discrepancy between the reference surfaces of base materials.
When base materials with slightly differing thicknesses are welded together, top or
bottom surfaces of the materials specified as reference surfaces are commonly
welded to joint such surfaces evenly. The discrepancy that may exist between thebase material reference surfaces is called mis-match.
Non-hazardous Leakage
Non-hazardous leakage is leakage that is not hazardous.
Non-metallic Liner
A non-metallic liner is a non-metallic seal composed of an inner layer of the COPV.
Out-gassing
Out-gassing is a phenomenon where a gas, such as water vapor (steam), carbon
dioxide, oxygen, hydrogen, or nitrogen, is emitted from the surface or inside of a
substance when the substance is exposed to high vacuum or high temperature, orsuch a gas itself.
Payload
Payload is a cargo item launched by a launch vehicle. For a rocket, payloads
include satellites or space probes carried on board.
Peak Stress
Peak stress is the stress increment to primary and secondary stresses due tostress concentration or local stress generated by local structural discontinuities
such as uneven surfaces and notches.
Penetration Bead
Penetration bead is regular corrugated bead generated on the opposite side (bac k

12

side) of the electrode in one-side welding.
POGO
POGO is self-induced vibration manifoldly generated from vibrations of a liquid
propellant launch vehicle body and a propellant feed system.
Pressure Cycle Test
The pressure cycle test is a test to confirm that high-pressure gas equipment
possesses the specified life by applying pressure simulating the actual pressure
pattern.
Pressure Vessel
A pressure vessel is a container used to store pressurized gas whose pressure isgreater than or equal to 1.0 [MPa] at operating temperatures (design temperature)or to store liquid gas whose pressure is greater than or equal to 0.2 [MPa] at
operating temperatures (design temperature).
Primary Bending StressPrimary bending stress is bending stress generated by pressure or othermechanical load, in structures having no discontinuous part in general and local
construction.
Proof Factor
Proof factor is a design coefficient used to determine defect detection pressure
test. The proof factor determines proof life.
Proof Pressure Test
A proof pressure test is a test to confirm whether the part can endure the specified
pressure safely or not by applying pressure to the part to receive the internal(external) pressure of high-pressure gas equipment.
Proof Test (Defect Detection Pressure Test)
Defect detection pressure test is a test to assure that a fabricated pressure vessel
is free of initial defects significant enough to burst the vessel during operation.
Proof Test Pressure (Defect Detection Test Pressure)
Defect detection test pressure is the pressure used for proof tests. It is equal tothe product of the MEOP and a proof factor. It may also be calculated based on
initial flaw size.
Propellant Tank
A propellant tank is a container used to store liquid propellant for laun ch vehicles
and their payloads.

13Qualification Test
The qualification test is a test to confirm that systems or subsystems of the launchvehicles and their payloads possess sufficient functions, capabilities,
environmental tolerance, and durability to undergo launch and on-orbit operation.
Secondary Stress
Secondary stress is a vertical stress or shearing stress generated by constraintsof neighboring structures or self constraints, and is self-limiting.
Shakedown
When the stress exceeds yield strength of a material due to loading cycles whichcorrespond to primary and secondary stress, the material shows elasto -plastic
behavior and deformation of the material may progress. Shakedown refers to aphenomenon in which elastic behavior of the material appears aft er initial elastoplastic behavior and deformation will not occur.
Sloshing
Sloshing is the back-and-forth movement of liquid propellant in the propellant tanks
for liquid propellant launch vehicles.
Stress Corrosion Cracking
Stress corrosion cracking is a phenomenon in which a corrosive environment anda constant sustained tensile stress embrittle an alloy causing a flaw which
eventually destroys the alloy.
Stress Intensity
Stress intensity is twice the maximum shearing stress at a point given by theequivalent strength of combined stress, which is the algebraic difference of the
maximum value and the minimum values of principal stresses. When there arethree principal stresses,  1 >  2 >  3 , stress intensity S is defined by S =  1 -  3 .
Stress Rupture
A phenomenon where a crack develops over time under a continuous load andeventually leads to a rupture.
Stress Rupture Strength
Tensile strength when a rupture occurs due to stress rupture under a continuous load.
Structural Element
A structural element is an element of high-pressure gas equipment required toretain pressure.
Ultimate

14

Ultimate refers to the point at which the structure is collapsed or destroyed or atwhich the structure no longer supports the loads.
Ultimate Load
Load limit multiplied by tensile strength, design burst pressure, or ultimate load
safety factor. Requirements are usually for no failure under the ultimate load.
Waiver
A waiver is a written authorization granted for use or acceptance of equipment notconforming to the specified requirements.
Weldability
Weldability is a property indicating whether a material is suitable for welding andthe degree of difficulty in welding. Weldability can be roughly classified in terms of
welding procedures (joint ability) and usability of a welded structure.
Welding Bead
Welding bead is welding metal and deposited metal produced by the weld path;often simply called bead.
Welding Deformation
Welding deformation is deformation in materials or structures due to welding. It i scommonly called welding distortion. Lateral bending is most general and is called
angular deformation.
Yield Ratio
Yield ratio is defined as material yield stress divided by tensile strength.
Special treatment
If conditions do not meet requirements in the technical standards, the reasons fornot satisfying those requirements and alternative measures, a description ofcontents of studies for assuring safety, and the like, confirming that the intent of
the technical standards is satisfied and showing conformance to the provisions of
the technical standards.
Porosity
Spherical cavities created in welds due to gas entrainment. Blowholes.

152. Design and Fabrication Procedure for High-Pressure Gas Equipment forSpace Use
2.1 Development Flow
High-pressure gas equipment installed in launch vehicle and the payload shallgenerally be developed according to the flow specified in Figure 2-1. Althoughslight changes due to individual system requirements shall be accepted, validity ofthe design shall be verified by prototype model which is fabricated as same
configuration as flight model and tested before flight model is fabricated. This
scheme is different from ground use high-pressure gas equipment and is required
to allow space use high-pressure gas equipment to adopt lower safety factor thanthat for ground use. Reusable high-pressure gas equipment requires additional
process for re-flight. Reusable high-pressure gas equipment shall comply withrequirements in section 6 of “Reuse”.
Design and fabrication shall also be appropriately managed in accordance with theseparately specified configuration management program, reliability program,quality assurance program and system safety program.
2.1.1 Design(1) Design condition
Specify the design conditions according to paragraph 3.1. In particular, take into
account of all environmental conditions (including pressures and loads) to which
high-pressure gas equipment are exposed from the fabrication to completion ofplanned fights. Accordingly set design conditions for design rating.
(2) Structural typeSet structural type described in paragraph 3.2 according to the design conditions.
(3) Selection of material
Conduct trade-off of materials described in paragraph 3.3 based on the structural
type described in 3.2 and select appropriate materials. Conduct a materials test
and work test if necessary, when select materials.
(4) Calculation of thickness
Calculate thickness according to paragraph 3.4.
(5) Detailed analysis
Perform detailed analysis according to 3.5 and confirm that proper margin isallowed for strength, buckling (if necessary), and life, and that the design issatisfied with the design conditions described in paragraph 3.1. If the design is notsatisfied, look back structural type, material, thickness and others, and perform theanalysis again.

16

2.1.2 Qualification test
After the design described in paragraph 2.1.1 completed, fabricate a prototype
model as the same configuration as the flight model and verify validity of the designby conducting qualification test such as vibration test, pressurized cycle test, andburst test. Additionally, set valid fabricating process and inspection process. Verify
validity and quality of those processes through the qualification test or othermethod.
When necessary, conduct a material basic test, determine and verify the welding
method, and conduct the prototype model test as development test prior to thequalification test to confirm design data, fabrication method and test method
needed to fabricate a prototype model to be used for qualification test.
2.1.3 Flight model fabrication
Fabricate flight hardware after the qualification test is completed and validity of thedesign and the fabricating process is verified. Conduct an acceptance test for flighthardware to verify the possibility of accepting the deliverable item. An acceptancetest is conducted to verify that the flight hardware fabricated according to theapproved design does not have any material or fabricating flaw.
2.2 Exemption Provision
When one of the following conditions is met, a part of the requirements in thisstandard shall be exempted from application at design/fabrication compatibility
review.
2.2.1 High-pressure gas equipment of safety factor 4 or more
(1) Exempt conditions
Some requirements in this technical standard are exempt when metallic highpressure gas equipment possess a tensile strength safety factor greater than orequal 4, when a COPV possesses a safety factor greater than or equal to 4 fordesign burst pressure.
(2) At design conformity assessments
The following review provisions in section 3. ”Design” can be exempted bysubmitting thickness calculation results of shell plate, head and piping whencompatibility in terms of design is reviewed.
3.5.1 Stress analysis
3.5.2 Judgment of LBB occurrence (analysis and test)
3.5.3 Fatigue damage analysis and test
3.5.4 Crack growth analysis and test17

In addition, the following item required by section 4, "Fabrication" does not
apply to piping.
4.7.2(3) Nondestructive inspections(3) At fabrication conformity assessments
Some requirements in section 4, “Fabrication” may be exempted by submitting
documents specified below for fabrication compatibility review.
a. A mill sheet for metallic materials used, an inspection report for composite
and nonmetallic materials, etc.
b. Result of pressure test using more than 1.5 times of MEOP
c. Result of leak test using more pressure than MEOP
d. Nondestructive inspection results for welds(4) Qualification tests
The qualification tests described in paragraph 5.2 may be exempt.
If specific capability such as the environmental tolerance, the tendency ofmaterial quality change, and so on is not enough for this standard, someappropriate qualification tests should be added.
2.2.2 High-pressure gas equipment that have been qualified(1) Exempt conditions
Exempt items include the follow: those developed by organizations such as NASDA,
ISAS, NAL, NASA, and ESA for use in satellites, rockets, or related projects; items
developed for other spacecraft, subjected to design conformance reviews basedon these technical standards and issued conformance certificat ion; and devices
that have passed safety reviews at launch sites in the US, Europe, and elsewhere,
and for which certification tests have been completed (hereinafter, “qualified
equipment”).

Qualified equipment shall be used for projects subject to this technical standard in
the following three ways:
a. Use equipment newly fabricated using the same design.
b. Use equipment already fabricated.
c. Use equipment fabricated with slight modifications in the same design that will
not affect item strength.

(2) At design conformity assessments
Some requirements in section 3, “Design” may be exempt by submitting the18

documents specified below for design compatibility review.
a. Operating conditions (pressure, temperature, vibration, etc.) do not exceed
those qualified at the time of device development.
b. Design data prepared for a qualification test of the qualified equipment shallmeet the requirements of this technical standard.
c. If any analysis required in this technical standard has not been conducted fora qualification test of the qualified equipment, conduct the analysis according
to this technical standard.
(3) A t fabrication conformity assessments
If using an item already fabricated according to the same design, the somerequirements in section 4, “Fabrication” can be exempted by submitting theinspection records (including mill sheets, proof pressure test recor ds, leak test
records, nondestructive inspection records, and dimension (thickness) inspection
records) for design compatibility review.
2.2.3 Purchased item
(1) Corresponding conditions
There is a product catalog, product specification s, etc., allowing purchase by
specification of a model number, etc., and the following conditions a. –d. aredescribed in a product catalog, technical data, product specification, or othersource.

a. Operational condition is within the operation range.
b. Test equivalent to a qualification test is performed.
c. Safety factor shall be more than 1.5 for yield stress and more than 2.5 fortensile strength.
d. The purchased item has heritage on the ground or in space.
(2) At design conformity assessments(1) Examination items required by section 3 “Design” can be exempted bysubmitting documents indicating the relevant conditions, except for the following
items. However, in the case of piping, submit the documents in paragraph2.2.1(2).
3.1.3.1 Safety coefficients related to pressure
3.1.5(3) Lifetime requirements for operational and displacement cycles
Also, the following examination items required by section 4 “Fabrication” do not
apply:
4.1 Finishing and molding

19

4.2 Welding
4.3 Heat processing
4.7.1 Material acceptance inspections
4.7.2 Parts inspections (for metallic materials)
4.7.3 Welded parts inspections(3) A t fabrication conformity assessments
Some requirements in section 4, “Fabrication” may be exempted by submitting
the inspection record (including proof pressure test record, leak test record, andfunctional test record) or the certificate issued according to acceptanceinspection procedure for design compatibility review. However, in the case of
piping, submit the documents in paragraph 2.2.1(2).
2.2.4 High-pressure gas equipment for space use certified as conforming toother technical standards
For flight item of high-pressure gas equipment developed and certified asconforming to the following standards (1) ~ (3), it is considered that the technicalstandards are met by submitting the documents a ~ c and the explanatory materials
for items d and e.
a. A certificate issued by the certification organization *1 indicating that theequipment design meets standards (1) ~ (3) (Hereafter referred to as a“certificate of design conformance”)
b. A ce rtificate issued by the high-pressure gas equipment manufacture indicatingthat the flight product was manufactured to meet the requirements of standards(1) ~ (3). (Hereafter referred to as “certificate of fabrication conformance”)
c. A consent document of certificate of fabrication conformance issued bypersons requesting JAXA to examine conformity with this technical standard(Hereafter referred to as a “consent form”)
d. A statement describing operating conditions (MEOP, expected life, etc.),
design conditions (safety factor), a development test and a certification test
conducted; ande. A certificate of a materials quality and performance as a flight product *2,*3 , adimension inspection report *2,*4 , a nondestructive testing report *2 , a proof
pressure and airtight test report, and a pressure cycle life report *5 .
“Space systems - Pressure vessels and pressurized structures- Design and operation”(2) Example criteria for container security regulations(3) Other standard that is considered to be equivalent. (e.g. MIL-STD-1522A)(1) ISO 14623

20

*1: Here, accrediting bodies are defined as government institutions such asNASA or ESA, or public third-party organizations such as KHK or private
certification organization certified by a public third party.
*2: In case it cannot be submitted, indicate the reason.
*3: Excludes purchased items such as valves that satisfy the “corresponding
condition” in 2.2.3(1)*4: Excludes piping items and purchased items that satisfy the “corresponding
condition” in 2.2.1(1)*5: Limited to pressure vessels
2.3 Special Treatment
If the requirements of this technical standard are not satisfied, perform special
treatment and submit a special treatment report with conformity assessments forthese technical standards as pertaining to design and fabrication. This report should
indicate considerations regarding the reasons for not satisfying the provisions of
this technical standard, alternative measures, the basis for ensuring safety, etc.
Exemptions from conformity assessments in the relevant parts of these technicalstandards will be permitted only when the contents of this report can be confirmed
as valid. Note that the reporting method must be based on the technical document
CSA-115016 “Special Treatment Method for Technical Standards Conformity
Examinations of High-Pressure Gas Equipment for Space Use.”

21

Design Requirements Determination

Structure Determination
Material Selection
DESIGN

Thickness Calculation
Detailed Analyses

No
Judgment

Yes
Test Article Fabrication

Acceptance test *1

QUALIFICATION T EST

Qualification Test *2

Design compatibility review
No
Judgment

Yes
Flight Model Fabrication

Acceptance test

FLIGHT MODELFABRICATON

Fabrication compatibility review
No
Judgment

Yes
Installation *3*1 As a part of qualification test, test identical with the acceptance test performed by
the flight model shall be conducted*2 Development test (material basic test and determination and confirmation of
welding method, and prototype test) can be conducted before qualification test.
*3 W hen malfunction is found and equipment is exchanged during installation,
rectification shall be reviewed.

Figure 2-1 High-pressure Gas Equipment Design and Fabrication Flow22

3. Design
3.1 Setting of Design Conditions
3.1.1 Function and performance requirements
High-pressure gas equipment shall endure the environmental conditions ofpressure, load, and temperature, and others expected from the fabrication phaseto the completion of the planned number of flights and meet functional andperformance requirements of the system incorporating the high-pressure gas
equipment.
3.1.2 Load and temperature conditions
The following load history shall be taken into account for setting load conditions.
Fabrication test phase

Proof test pressure
Proof test pressure (Defect detection pressure test,
if conducted)
Leak test pressure

Ground handling phase

Load applied during transportation
Load applied during assembly
Leak test pressure
Load applied by ground surface wind
Load applied during propellant loading test
Load applied during captive firing test (CFT)Load applied during cryogenic checkout

Flight phase

Load applied during flight

3.1.2.1 Maximum Expected Operating Pressure (Limit pressure)
Establish the MEOP for high-pressure gas equipment (which is limit pressure forlaunch vehicle propellant tanks).
Consider all pressure conditions to which the high-pressure gas equipment are
exposed from the fabrication phase to the completion of the planned number offlights in establishing the MEOP.
Calculate the enveloped values of the pressure distribution history and make its
maximum pressure the MEOP (limit pressure).
Consider pressures applied during the fabrication test (except proof pressure test
and defect detection pressure test), ground handling and flight.
(1) Limit pressure to launch vehicle propellant tank
For propellant loading and flight, pressure at the liquid head of the propellant
generated by acceleration shall be considered in addition to the pressurization

23

pressure at ullage. Acceleration during flight shall be established considering static
acceleration along the axis of the vehicle and dynamic acceleration due to low
frequency vibration. For low- frequency vibrations, consider propellant sloshing,
POGO, transient response at engine ignition, transient response due to sudden
gusts of wind, and so on.
[MEOP (limit pressure)] = [Maximum pressurized pressure at ullage] + [liquid
head pressure]
Limit pressure shall be the maximum pressure in every vehicle axis direction.
The maximum pressurization pressure at ullage shall be determined considering
the followings:
1) Nominal operating pressure,2) Pressure control range,
3) Pressure overshoot,4) Pressure measurement error,
5) Pressure applied during vent value operation,
6) Pressure loss in pipes during vent valve operation,7) Ambient atmosphere pressure, and8) Other[Liquid head pressure] = [Propellant density] x [Acceleration in the vehicle axis
direction during flight] x [Height of liquid surface](2) MEOP of high-pressure gas equipment other than launch vehicle propellant tanks
The pressure increment caused by acceleration as well as pressurization pressureduring flight shall be considered. However, pressure increment smaller than thepressurization pressure may be ignored.
(3) Correction pressure for a cryogenic propellant tank at normal temperature
At normal temperature, a cryogenic propellant tank and the like shall bepressurized at a pressure equal to or less than the limit pressure corrected for theratio of material yield stress at design temperature and material yield stress at
normal temperature as shown in the following equation.
[Pressurized pressure at normal temperature]  [Limit pressure at designtemperature] x [Yield stress at normal temperature] /[Yield stress at design temperature]
Design burst pressure for a cryogenic propellant tank and the like at normal
temperature shall be corrected with for the ratio of tensile strength at desi gn
temperature and tensile strength at normal temperatures as shown in the following

24equation.
[Design burst pressure at normal temperature] = [Design burst pressure at designtemperature] x [Tensile strength at normal temperature]/ [Tensile strength at design temperature]
3.1.2.2 Load during flight
During flight, high-pressure gas equipment receives the flight load (external load)
and the pressure load. The flight load shall be considered to be the following loads
at a certain time during the flight.
Validity evaluation criteria for the flight load or that of analysis method is out of
scope, since the flight load shall be given by space system.
(1) Launch vehicle propellant tank
Examples of the compressive loads in the vehicle axis direction
1) Engine thrust2) Inertial force in the vehicle axis direction3) Payload inertial force
4) Air drag5) Load due to low frequency vibration response
Examples of shearing forces perpendicular to the vehicle axis
1) Aerodynamic force during flight in attack angle
2) Aerodynamic force due to gusty wind3) Engine thrust component perpendicular to the vehicle axis (while steering)4) Inertial force component perpendicular to the vehicle axis
5) Load due to low frequency vibration response
Examples of bending moments
1) Moment generated due to distributed shearing force perpendicular to thevehicle axis
Use conservative value of parameter which has variance, such as wind direction
and wind velocity. Figure 3.1.2-1 shows the limit load of the H-II launch vehicle
during flight for reference.
(2) High-pressure gas equipment other than launch vehicle propellant tank
For high-pressure gas equipment other than launch vehicle propellant tank, thefollowing accelerations and environmental conditions during flight shall be25considered.
a. Quasistatic acceleration
Specify quasistatic acceleration with a sum of static acceleration and vibrationload in the vehicle axis direction and perpendicular to the vehicle axis which
affect the center of gravity of high-pressure gas equipment at the time of avehicle launch.
b. Sinusoidal wave vibration acceleration
Specify sinusoidal wave vibration acceleration by converting a transient
response and self-induced vibration propagating from the main body of a launchvehicle at the time of a vehicle launch and completion of the first - and secondstage firing and so forth.
c. Acoustic and random vibration environment
Specify acoustic and random vibration environment either by random vibration
at equipment installation surface on a launch vehicle or payload defined as
random vibration response due to acoustically induced vibr ations during vehicle
launch and transonic aerodynamic vibrations, or acoustic vibration whichcorrelates with sound strength directly imparted on the installed equipment.
Note that acoustic and random vibration environments may not be equivalent toeach other due to differences in boundary conditions when the installed
equipment is small or its mass to volume ratio is large.
d. Impact environment
When retention or release device or a similar device using pyrotechnics is
operated, ignition of pyrotechnics, loosening of retention release mechanism orcollision of movable parts may cause an impact. The impact force shall be
described in a Fourier spectrum by the response spectrum or impact response
spectrum.
3.1.2.3 Load during ground handling
During ground handling, launch vehicle propellant tank is loaded the groundhandling load in addition to the pressure load. The ground handling load shall beconsidered the following loads.
Examples of the compressive load in the vehicle axis direction
1) Load induced by the launch vehicle airframe in vehicle axis direction2) Mass of the payload
Examples of the shearing forces perpendicular to the vehicle axis
1) Aerodynamic force due to ground surface wind26

2) Static load generated during transportation
3) Load due to low-frequency vibrations during transportation
Examples of bending moment
1) Moment generated due to distributed shearing force perpendicular to thevehicle axis.
For high-pressure gas equipment other than launch vehicle propellant tanks,
ground handling load shall be smaller than the flight load. Ground handling load
shall be calculated by multiplying analyzed ground handling load by the special
factor, considering operator’s safety and uncertainty of load. The special factor
shall be greater than 1.06.
Validity evaluation criteria for the ground handling load or that of analysis method
is out of scope, since the ground handling load shall be given by the system.
3.1.2.4 Temperature condition
Design temperature of high-pressure gas equipment shall be set considering all
temperature conditions to which the equipment will be exposed through thecompletion of the planned number of fights. Consider the temperatures during
fabrication testing, ground handling, and flight.
High temperature condition which causes creeping problem of material is out of
scope in this standard.

27

Figure 3.1.2-1 Limit Load of H-II Launch Vehicle during Flight (Example)

28

3.1.3 Safety factor
Safety factor for high-pressure gas equipment is shown below.
3.1.3.1 Safety factor for pressure
For metallic high-pressure gas equipment, safety factor for material strength isspecified in Table 3.1.3-1. For COPV, safety factor for design burst pressure is
specified in Table 3.1.3-2.
Table 3.1.3-1 Safety Factor for Material Strength of Metallic High-Pressure
Gas Equipment
Safety Factor
No.

Condition(Note 1)

Structural Category
Yield Stress ( y )*Tensile Strength ( u )Possible toapproach1

Pressure Vessel

1.5 or more

2.0 or more

2

Pressure Vessel(1+[ safety factor fortensile strength] )/ 2 or
more

1.5 or more, less than Impossible to2.0
approach (Note 2)

3

Pressure Piping and
Fitting (38.1 mm ormore in diameter)

1.5 or more

2.5 or more

Possible toapproach (Note 3)

4

Pressure Piping and
Fitting (Less than
1.5 or more
38.1 mm in diameter)

4.0 or more

Possible toapproach (Note 3)

5

Bellows

1.0 or more

1.5 or more

Impossible toapproach (Note 2)

6

Bellows

1.5 or more

2.5 or more

Possible toapproach

7

Other Components

1.5 or more

2.5or more

Possible toapproach (Note 3)

8

Launch Vehicle
Propellant Tank

1.0 or more

1.25 or more

Impossible toapproach*: or 0.2% of proof stress (hereafter referred to as yield stress)

Table 3.1.3-2 Safety Factor for Design Burst Pressure of COPV
No.

Conditions(Note 1,4)

Safety Factor

1

2.0 or more

Possible to approach2

1.5 or more, less than 2.0

Impossible to approach (Note 2)

Note 1 Indicates whether personnel can approach the equipment when MEOP isapplied and stabilized. When pressure of less than one fourth of the design

29burst pressure is applied, personnel can approach the equipment at any
time.
Note 2 Personnel can approach when LBB occurrence is confirmed. When LBB
occurrence is not confirmed, personnel can approach the vessel afterpressure is stabilized when pressure of less than half of design burst
pressure is applied to pressure vessel.
Note 3 When pressure piping, fitting, and other components do not meet the above
safety factor requirements, such components shall be categorized aspressure vessel.
Note 4 If the capacity is 500 L or less and tensile testing is performed on the basematerial of liners (excluding nonmetal liners) or welded parts duringcertification testing, access by personnel must always possible when thefollowing pressures are applied:
Carbon fiber composite pressure vessels: 1/2.25 of design burst
pressure or lessAramid fiber composite pressure vessel: 1/3 of design burst pressureor less
Glass fiber composite pressure vessel: 1/3.5 of design burst pressureor less
3.1.3.2 Safety factor for flight load
For metallic high-pressure gas equipment, the safety factor for material strengthis defined in Table 3.1.3-3.
For COPV, the safety factor for yield stress (metallic liner) and ultimate load isdefined in Table 3.1.3-4.
The load shall be the flight load which is shown in paragraph 3.1.2.2.

Table 3.1.3-3 Safety Factors for Material Strength of Metallic High-Pressure Gas
Equipment for Flight Load
Safety Factor
Structural Category
Yield Stress ( y )Tensile Strength ( u )1.0 or more

1.25 or more

Metallic high-pressure gas equipment

Table 3.1.3-4 Safety Factors for Yield Stress (Metallic Liner) and Ultimate load of
COPV for Flight Load30

Safety Factor
Structural Category

Yield Stress (Metallic Liner)(Note 1)

Ultimate load

COPV

1.0 or more

1.25 or more

Note 1 Safety factor for metallic liner does not yield when used.

31

3.1.3.3 Safety factor for buckling

If high-pressure gas equipment requires consideration of buckling, use the safety
factors for tensile strength, design burst pressure, and ultimate load l isted inTables 3.1.3-1 through 4 as the buckling safety factor.
3.1.3.4 Safety factor for ground handling (only for launch vehicle propellant
tanks)
Safety factor for ground handling shall be safety factor for launch vehicle propellant
tank in Table 3.1.3-1.
The load shall be the ground handling load which is shown in paragraph 3.1.2.3.
3.1.4 Interface requirements(1) Interface with the system
High-pressure gas equipment shall be installed in a launch vehicle or payload
system using a neighboring structure, supporting truss or bracket. The interface
shape shall satisfy environmental requirements (e.g. load, vibration, impact, heattransfer) from the system.
Cryogenic propellant tank shall be appropriately insulated to maintain atemperature increases in propellant caused by aerodynamic heating withinallowable limits.
(2) Interface with fitting
High-pressure gas equipment shall be capable of having propulsion system fittings
such as piping to supply propellant, pressurization piping, various valves, baffles,
thermo-sensors and pressure sensors; electric system fittings such as wire
harness; and pyrotechnics installed. The interface shape shall be suitable for
fittings such as flanges, bosses or brackets.
(3) Interface with Ground-Support Equipment
High-pressure gas equipment shall have, in general, piping to load and unloadliquid and gas. The interface shape shall be compatible with a pipe of Ground Support Equipment (GSE). The interface shape shall be selected appropriately
considering connection/disconnection with piping of GSE, leakage resistance, andso on.
Cryogenic propellant tank shall be appropriately insulated to keep propellant
evaporation losses within allowable limits.
3.1.5 Life requirements
The required life of high-pressure gas equipment shall be appropriately set
considering the period from the fabrication phase to the completion of the planned

32

number of flight as follows.
(1) Number of flight
The high-pressure gas equipment needs the specified number of flights for thelife assessment.
(2) Life requirement for pressure cycle
The number of the pressure loading cycle shall be considered all pressure loadingfrom the first proof test to the end of mission. The number shall include certain
extra pressure loadings that are needed by retesting or launch abort.
However, it is not required to set the number of the pressure loading cycle forpiping applied 2.2.1.
(3) Life requirement for operational cycle and displacement cycle
The operational life of the high-pressure gas equipment having movablemechanism such as electromagnetic valve and fill and drain valve shall beconsidered all operational cycle from the acceptance test to the end of mission.
For the bellows, displacement cycle is used as for the operational cycle. The
number shall include certain extra cycles for retesting and launch delay.

33

3.2 Structure Type Setting
3.2.1 Structure type of metallic pressure vessel
A metallic pressure vessel stores fluid such as propellant or pressurized gas andconsists of shell part which receives pressure load, mounting part which is used toconnect to launch vehicle or payload, and piping part which is used to pressurize
gas or used to load/unload propellant.
Shell forms various shapes such as sphere, ellipsoid, cylinder, cone or these
combinations. Shape of the shell shall be selected considering capacity, weight,
and installation and so on. Mounting shape shall be selected so that metallic
pressure vessel is installed in rocket or payload.
Examples of the structure type of metallic pressure vessel are shown in Figure 3.21.
3.2.2 Structure type of launch vehicle propellant tank
Structure of launch vehicle propellant tank shall, in general, consist of cylinder partand head (dome) part. It shall also include a flange to connect to the neighboring
structure, a lid to access an inner tank, a hole through which fluid such as
propellant and pressurizing gas is loaded/unloaded, and mounting on which
various fittings are installed.
Cylinder part structure shall be selected considering the strength to withstandvarious loads (internal load, and external load which affects launch vehicle during
flight and ground handling), fabricability, and handling ability.
Head part structure shall also be selected considering affecting loads (internalpressure load, and propagation of external load to a cylinder part such as engine
propulsion and inertial force), fabricability, and mass.
Head structure shall be spherical shell, ellipsoidal shell, or other shape d shell. A
tank with a common bulkhead which separates space of a tank.
Because the launch vehicle propellant tank structure affects the launch vehicle
length and weight, basic specification of the tank shall be determined after detailed
investigation during system design for the entire launch vehicle. Examples of thestructure are shown in Figure 3.2-2.
3.2.3 Structure type of COPVCOPV consist of liner layer (inner layer) and filament winding layer (outer layer).
Liner may be metallic liner or non-metallic (plastic or rubber) liner.
Both metallic and non-metallic liner shall preserve gas permeation barrier of thevessel. Metallic liner shall share to bear pressure loads, while non-metallic liner
shall not share in this technical standard.

34

To apply compressive stress to metallic liners, metallic liner may be subjected to
autofrettage by applying internal pressure after composite material forming iscompleted. The pressure to produce autofrettage shall be about 100 to 110% of
the proof test pressure.
(1) Spherical COPV
Spherical COPV shall consist of spherical liner and in-plane filament winding layer.
The total number of windings, winding angle, winding pitch and such shall be
determined considering geometric properties such as the shape of the port andvessel diameter, as well as liner material, external load supporting method andsuch.
Figure 3.2-3 shows an example of the structure of a spherical COPV.
(2) Cylindrical COPVThe structure of a cylindrical COPV consists of a liner, a body–head unit with areinforced filament winding layer, and a body reinforcement hoop layer ( a full-wrap
structure) or one in which only the body is reinforced with a hoop layer for a metalpressure vessel (a hoop-wrap structure).
Filament winding may be performed by in-plane winding, helical winding, or hoop
winding. These winding patterns are illustrated in Figure 3.2-4, and Figure 3.2-5
shows the hoop-wrap structure. Determine the winding method and other aspectsof container construction in consideration of its geometric form, such as its baseshape, container diameter, container length, and positioning of the hoop layer end,
as well as the liner materials, metal pressure vessel materials, the method forsupporting external loads, etc.
In designing COPV, the rupture mode and rupture position should be specified after
structural type is determined. For long cylindrical COPV, cylinder part should beselected as design evaluation part since the stress status of shell is easily
identified.

35

Spherical Vessel

Cylindrical Vessel (Spherical Dome)Cylindrical Vessel (Ellipsoidal Dome)Teardrop Vessel

Figure 3.2-1 Examples of Structures of Metallic Pressure Vessel

36

Cylindrical Tank
(Spherical Dome)Cylindrical Tank
(Ellipsoidal Dome)

PayloadLiquid Hydrogen Tank

Common Bulkhead
Liquid Oxygen Tank

Tank with a Common Bulkhead(2nd-stage Tank of Ｈ-II Launch Vehicle)
Figure 3.2-2 Examples of Structures of Launch Vehicle Propellant Tank

37

3rd layer
2nd layer
1st layer

Port
Liner

N: Number of layers

CFPRθ : W inding angle
P: Pitch = W 2/W 1

N t h layer
Equator

Bundle of fibers

Figure 3.2-3 Example of Structure of Spherical Composite Overwrapped
Pressure Vessel (COPV)

38

Helical Winding

In-plane Winding

Hoop Winding

Figure 3.2-4 Overview of Filament Winding Types

39

Figure 3.2-5 Example hoop-wrap construction40

3.3 Material Selection
Materials for high-pressure gas equipment should be selected in consideration of
the characteristics described in paragraph 3.2 “Structure Type Setting” andparagraphs 3.3.1–3.3.4. However, if materials other than those specified in thefollowing standards (1)–(3) are used for high-pressure gas equipment with a safety
factor of less than 3.5, perform the basic testing of materials as described inparagraph 5.1.1.
(1) AMS Standards(2) MIL Standards(3) FS Standards
3.3.1 Mechanical property(1) Metallic material
Metallic material used for high-pressure gas equipment shall possess specificmaterial strength and adequate reliability. The specific value applied to the design
shall be equivalent to A value in MMPDS-01. Factors which affect mechanicalproperties include temperature, pressure loading time, number of cyclic loads , andprocessing conditions for base material and welded parts. Consider these factors
when selecting materials.
The yield ratio of the metallic materials used for launch vehicle propellant tanks
shall satisfy the following so that plastic collapse is brought ultimately. If metallic
materials do not satisfy the following, show grounds to be safe.
Yield Ratio =Yield Stress 0.85Tensile Strength(2) Composite material
Select composite material considering filament winding, cure condition, othernecessary conditions, and rupture characteristics.
(3) Non-metallic liner
Non-metallic material used for liner of COPV shall have greater breaking strain
than composite material under the same operating temperature. The characteristic
value shall have adequate reliability. In addition, select material considering theprocessing conditions of shaping, bonding and others.
3.3.2 Fracture property
Material to use shall possess appropriate fracture property to flaw growth due tocyclic and continuous loads in the operating environment.

41

Fracture toughness to flaw growth due to cyclic and continuous loads may not be
considered for material used for non-metallic liners.
3.3.3 Compatibility
Materials used shall be adequately compatible with all environmental conditions
such as loaded fluids and others without causing corrosion, stress corrosion
cracking, and others.
(1) Compatibility with loaded fluids
Materials contacting the fluids loaded into high-pressure gas equipment shall becompatible with such fluids and shall not degrade equipment ma terials, or
accelerate deterioration or decomposition of loaded fluids.
Select materials according to NASA document SE-019-094-2H.
Composite material used for COPV which do not contact the loaded fluids shall not
be considered the compatibility with the loaded fluids.
(2) Compatibility with the external environment
When exposed to external environments, materials shall resist environmental
effects by themselves or with proper protective finishing.
For non-metallic materials used in a COPV, consider the fol lowing environmental
tolerances different from those for metallic materials.
a. Out-gassing: Out-gassing generated from materials shall be within specified
limits.
b. Radioresistance: Materials shall endure the radiation environment to which the
COPV is exposed on the orbit.
c. Impermeability: Materials shall have the required impermeability to gas andloaded fluid under the operating environment.
(3) Compatibility with fluids used
Fluids used in factories and tests shall not contaminate or degrade materials during
material treatment, processing, inspection, test, transportation, or storage.
Furthermore, material reactions shall not produce any hazardous products.
(4) Compatibility with dissimilar metals
When dissimilar metals are used contacted each other, select a combination of
metals which is less likely to cause dissimilar metal corrosion according to therequirements in MIL-STD-889.
(5) Compatibility between composite material and liner
Select a combination of composite and liner which does not cause degradation by42

corrosion of liner or provide appropriate treatment to prevent such degradation.
In particular, consider corrosion when conductive fiber is used as composite.
3.3.4 Fabricability
Fabricability is important element in selecting materials. When determining the
fabrication method, consider materials and fabricability required to produce
products with specified shapes, performance, and quality. In other words, ensure
the following major requirements regarding fabricability is satisfied.
(1) Quality and availability
Materials shall possess appropriate quality and availability.
(2) Forming properties and machinability
Materials shall be shaped by forming or machining to obtain required shape,
dimensions, and appropriate material strength.
Materials used for COPV shall be shaped by forming to obtain required shape,
dimensions, and appropriate breaking elongation.
(3) Weldability
Materials shall possess adequate weldability if fabrication process includes
welding.
(4) Formability of composite material
Materials used for COPV shall be shaped by filament winding and heat curing toobtain required shape, dimensions, and appropriate material strength.

43

3.4 Thickness Calculation
3.4.1 Thickness calculation for metallic pressure vessel
Calculate thickness according to the equations below. If other equations are used,provide the rationale and sources.
3.4.1.1 Thickness of cylindrical shell plate
This applies to a cylindrical shell with the minimum thickness of the shell plate
being equal to or less than 0.25 of the inner diameter of the shell.
t

PD
2S m  1.2P

(3.4.1)

wheret:

Minimum thickness of shell plate

P: MEOP
D: Inner diameter of the shell
S m : Design stress intensity
Material Yield Stress ( y ) * Safety Factor for Yield Stress * * andSm = Small value among  Material Tensile Strength ( u) *  Safety Factor for Tensile Strength * * * Use the value specified at the design temperature.
For materials used at cryogenic temperature, yield stress or tensile strength
at normal temperature may be used if the cryogenic yield stress or tensile
strength at cryogenic temperature exceeds those at normal temperature. For
weld parts, consider the increased weld thickness specified in paragraph4.2.1 (2).
** Use the value which is specified in Table 3.1.3-1 and is actually used.
For the piping

t

PD 0
2S m  0.8P

(3.4.1a)where
D 0 : Outer diameter of the piping

44

3.4.1.2 Thickness of spherical shell plate
This applies to a spherical shell with the minimum thickness of the shell plate being
equal to or less than 0.178 of the inner diameter of the shell.
t

PD
4S m  0.4P

(3.4.2)

3.4.1.3 Thickness of conical shell platetPD
2cos  Sm  0.6P (3.4.3)

where
D: Inner diameters of the parts used to calculate the minimum thickness ofthe shell plate, measured perpendicularly to the cone axis:One half of vertical angle of the cone []3.4.1.4 Thickness of torispherical head plate or total hemispherical head platet

PRW
2S m  0.2P

(3.4.4)

where
R: Internal radius of the central part of a torispherical head or total
hemispherical head
W: Coefficient relating to a torispherical shape, obtained by the following
equation (for a total hemispherical shape, W is 1)

W = 1 3 +
4

R
r1 


where
r 1:

Internal radius of the round corner of a torispherical head

3.4.1.5 Thickness of semi-ellipsoidal head platet

PDK
2S m  0.2P

(3.4.5)

where
D: Major axis of ellipsoid inside of head
K: Coefficient determined by head shape, obtained by the following equation45

2
1 D  
K = 2 +   
6   2h  

where
h : Half of minor axis of ellipsoid inside of head
3.4.1.6 Thickness of conical head plate(1) For a conical part of head with vertical angle equal to or less than 140 degreestPD

2cos  Sm  0.6P (3.4.6a)where
D: Inner diameter of the parts used to calculate the minimum thickness ofa head, measured perpendicularly to the cone axis:One half of the apical angle of the cone [ ](2) For a conical part of head with vertical angle exceeding 140 degrees
Use the minimum thickness which is smaller value obtained either by theequation (3.4.6a) above or by the equation below.
t  0.5(D 0  r2 ) 
90

P
Sm

(3.4.6b)where
D 0 : Outer diameter at the end of conical headr 2:

Internal radius of the round part connecting to the end of conical head46

3.4.2 Calculation of plate thickness of launch vehicle propellant tank
Plate thickness shall be calculated according to the loading conditions during flight.
Calculated plate thickness shall be verified for flight and ground handling according
to detailed analysis described in paragraph 3.5.
Calculate plate thickness according to the following equations. If other equations
are used, provide the rationale and source.
3.4.2.1 Cylindrical shell
Plate thickness of cylindrical shell may vary according to the magnitude of load in
the vehicle axis direction. However, in any vehicle axis directions, plate thickness
shall not be thinner than the thickness calculated based on the circumferential
stress and the thickness calculated based on load in the vehicle axis direction.
When waffle or isogrid is used in plate structure, equivalent thickness which is
calculated with the effect of rib/flange reinforced flat plate can be used. (Note 1)
Note1: Figure 3.4.2-1 shows the equivalent thickness of the isogrid flat plate asreference.
(1) Calculation of plate thickness for circumferential stressCalculate plate thickness for circumferential stress according to equation (3.4.1)
in paragraph 3.4.1.
For the thickness, equivalent thickness may be used for isogrid reinforced flat plat.
(See Figure 3.4.2-1)(2) Calculation of plate thickness for the stress in the vehicle axis direction
The stress in the vehicle axis direction in the cylindrical shell of a launch vehicle
propellant tank has tensile and compressive components due to the bending
moment during flight. Therefore, calculate thickness for each case as described
below. For the compressive stress, thickness shall be calculated in terms of bothcompressive strength and buckling strength.
For the tensile stress generated by the bending moment
̶ Calculate thickness in terms of strength according to a . below.
For the compressive stress generated by the bending moment
̶ Calculate thickness in terms of strength according to b . below.
̶ Calculate thickness in terms of buckling strength according to c . below.
Thickness need not be calculated when (1) the equivalent tensile force in thevehicle axis direction (F eq ) a is determined to be compressive in case a, and (2) theequivalent compressive force in the vehicle axis direction (F eq ) b is determined to
be tensile in case b.
a. Calculation of plate thickness for the stress of the tension component generated47

by the bending moment during flighttFeq a(3.4.7)

DSm

Feq a  F  4M  D P
2

D

4

where
(F eq ) a : Maximum value of equivalent tensile force in the vehicle axis
direction with pressure load in load historyt:

Plate thickness. Equivalent plate thickness can be used for isogrid
reinforced flat plate. (See Figure 3.4.2-1)

D:

Inner diameter

F:

Compressive force in the vehicle axis direction

M:

Bending moment

P:

PressureSm:

Design stress intensity

Material Yield Stress ( y ) * Safety Factor for Yield Stress * * andSm = Small value among  Material Tensile Strength ( u) *  Safety Factor for Tensile Strength * * *Use the value specified at the design temperature. For materials used
at cryogenic temperature, yield stress or tensile strength at normal
temperature may be used if cryogenic yield stress or tensile strength atcryogenic temperature exceeds those at normal temperature. For
welding part, the increased weld thickness described in 4.2.1 (2).

** Use the value which is specified in Table 3.1.3-1 and is actually usedb. Calculation of plate thickness for the stress of the compression component
generated by the bending moment during flighttFed b(3.4.8)DSm

Feq b  F  4M  D Pmin
2

D

4

where

48

(F eq ) b : Maximum equivalent compressive force in the vehicle axis direction
with pressure load in load historyt:

Plate thickness. Equivalent plate thickness can be used for isogrid
reinforced flat plate. (See Figure 3.4.2-1)

D:

Inner diameter

F:

Compressive force in the vehicle axis direction

M:

Bending moment

P:

PressureSm:

Design stress intensity

c. Calculating thickness for buckling during flight

tb =

F 

eq b

(3.4.9)

DS b

Sb 

 cr 

cr
Safety Factor *31  

2 1/2

E 2t
D

where
tb :

Plate thickness for buckling during flight(F eq ) b :Maximum equivalent compressive force in the vehicle axis
direction with pressure load in load history (The same equation as
used in (b) above.)P:

Pressure

Sb :Buckling strengtht:Plate thickness. Equivalent plate thickness can be used for isogrid
reinforced flat plate. If equivalent stiffness thickness is used,equivalent longitudinal elastic modulus shall be used at the sametime. (See Figure 3.4.2-1)

 cr :

Buckling stressD:

Inner diameter:Poisson ratio

E:

Longitudinal elastic modulus. Equivalent longitudinal elastic
modulus can be used for isogrid reinforced flat plate. When49

equivalent longitudinal elastic modulus is used, thickness ofequivalent stiffness shall be used at the same time.
:

Correction factor to reduction in buckling stress below thetheoretical value due to initial fabrication irregularity, and residual
stress ( < 1). Set this correction factor based on the test result,analysis result, or documented evidence and clarify the source.

* Safety factor for buckling as specified in paragraph 3.1.3.3.
3.4.2.2 Head (Dome part)Calculate plate thickness for the head to withstand internal loads during flight.
Plate thickness of the head shall not be less than the calculated thickness. Conductdetailed analyses described in paragraph 3.5 to confirm strength (including
buckling) when the payload load is applied to the head or when the back pressure
is applied to the common bulkhead.
(1) Torispherical head and total hemispherical head
Calculation of thickness for torispherical head shall be applied to the central partof torispherical head. Detail analysis shall be conducted according to paragraph
3.5 to confirm the strength of the part of round corners of torispherical head.
t＝PR
2S m－0.2P(3.4.10)

where
P:

Limit pressuret:

Minimum plate thickness

R:

Radius of the central part of torispherical head, or internal radiusof total hemispherical head

Sm:

Design stress intensity

 Material Yield Stress ( y ) *  Safety Factor for Yield Stress * * andSm = Small value among  Material Tensile Strength ( u ) *  Safety Factor for Ulitmate * * *Use the value specified at the design temperature. For materials used
at cryogenic temperature, yield stress or tensile strength at normal
temperature can be used when yield stress or tensile strength atcryogenic temperature exceeds yield stress or tensile strength at50

normal temperature. For weld parts, consider the increased weld
thickness as shown in (2) of paragraph 4.2.1.
** Use the value which is specified in Table 3.1.3-1 and is actually used
(2) Ellipsoidal headNN t＝great value amongand  SmSm 
(3.4.11)

1

2
2 2
N
a  R  b 
1-   1-   
aP 2b   a    a  









N 
N
1

2 

2
2
aP
aP 
R 
b 


1    1     

a 
a 


 

Figure 3.4.2-2 illustrates the parameters of a, b, R, P in above equations.
where
t:

Plate thickness

N:

Load in the radial direction per unit length

N:

Load in the circumferential direction per unit lengtha:Semi-major axis of ellipsoidb:

Semi-minor axis of ellipsoidR:

Distance from the central axis

P:

Limit pressure

Sm:

Design stress intensity (The same as in (1) above shall apply.)51

Non-dimensional parameter  bd
th
d
t





  31    1   1   2
2



1
2

Equivalent plate thickness

t eff  t1  
Equivalent stiffness thickness / Equivalent longitudinal elastic modulus

t*  t1

E*  E 0 1  2
Source: NASA-CR-124075
ISOGRID DESIGN HANDBOOK

Figure 3.4.2-1 Equivalent Plate Thickness of Isogrid Reinforced Flat Plate (Reference)52

Source: NASA-CR 912
SHELL ANALYSIS MANUAL

Figure 3.4.2-2 Ellipsoidal Head Load Distribution by Internal Pressure

53

3.4.3 Calculation of plate thickness of COPV
Figure 3.4.3-1 illustrates the flow for calculating plate thickness of COPV. Make
clear the formula used to calculate plate thickness. An example of calculation ofplate thickness for COPV with a metallic liner is sho wn below.
3.4.3.1 Calculation of plate thickness
3.4.3.1.1 Spherical COPV
Equation to calculate plate thickness when composite material of spherical COPV
is assumed to be pseudo isotropy material. (Effect of the poisson ratio is ignored.)tC 

1 k m  PB  R(3.4.12)EC  ε B

where
t c:

Composite material thickness when pseudo isotropy is assumedkm:

Sharing pressure ratio for metallic liner

P B : Design burst pressureR:

Radius of vessel

Ec:

Elastic modulus in the direction of the fiber of composite material

B:

Strain in the direction of the fiber at design burst pressure (breaking
strain)Next, calculate the thickness of the metallic liner using the following equation.
tm 

k m  PB  R
2  Smy(3.4.13)

where
tm:

Metallic liner thickness

S my : Metallic liner yield stress3.4.3.1.2 Cylindrical COPV (excepting hoop-wrap constructions)(1) When approach to begin with shell thickness calculation
This paragraph describes an example of calculating the shell thickness before
determining the head thickness.
a. Shell thickness
First, determine a winding angle  for the helical winding layer (or in-plane winding
layer) after determining the winding pattern based on vessel shape. Applying the54

following equations, calculate the thickness of the helical winding layer (or in -planewinding layer), and metallic liner.
k LP 
Em  LP  my(1   m )Smy

t =

tm 

(3.4.14)(P - P )DBP
4 E L cos 2 (

LB 

-k

my

(3.4.15))(PB  LP   Pp  LB  )D

(3.4.16)4(  LP    LB  )Smy

where
k:

Ratio of strain in the fiber (fiber strain during plastic deformation
processing) and metallic liner at autofrettage and yield strain of
the metallic liner (This depends on material properties of themetallic liner and a fiber. e.g., k = 2 to 3)

PB:

Design burst pressure

PP:

Autofrettage pressure

D:

Vessel diameter

S my :

Metallic liner yield stresstm:

Metallic liner thicknesst :

Thickness of the helical winding layer (or in-plane winding layer)

EL:

Modulus of elasticity in the direction of the fiber of the composite
materialEm:

Modulus of longitudinal elasticity of the metallic linerm:Poisson ratio of the metallic liner

 LB :

Strain of the composite material in the helical winding layer (or in plane winding layer) in the direction of the fiber at design burst
pressure LP :

Strain of the composite material in the helical winding layer (or in plane winding layer) in the direction of the fiber at autofrettagepressure my :

Yield strain of a metallic liner:Angle of the helical winding layer (or in-plane winding layer)

55

For the hoop winding layer, calculate thickness of using the following equatio ns.
PBD- Smy t m - EL  LB  t  sin 2 
th = 2EL  LBh
PpD
2 LPh (3.4.17)

 Smy t m  EL  LP  t  sin 2 (3.4.18)

EL t hwhere
 LBh :

Strain of the composite material in hoop winding layer in the
direction of the fiber at design burst pressure LPh :

Strain of the composite material in the hoop winding layer in the
direction of the fiber at autofrettage pressureth :Thickness of the hoop winding layer

b. Head thickness
Determine the distribution of the thickness of the composite material and the
distribution of crossing angles of the fiber based on the thickness of the shell
determined in a. above. Assume that the thickness of the metallic liner at the headis consistent. The shape of a head can be determined with equation (3.4.19) below.
(Source: NASA-CR-72124)





1

1
2  2  1 2  k
1

m
 =

tan 2   1   2  1 2  tan 2  - 1 
2
 

 2



 



(3.4.19)(At an even tension curved surface)(3.4.20a)where
tan 2  =tan 2  

 02

 2 -  0 

2tan  tan  e  2(When in-plane winding is used)1  2 2  tan  e 2 
(3.4.20b)

Symbols r and z represent coordinates in Figure 3.4.3-2.  and ζ are nondimensional coordinates of r and z. R is the radius of the shell.
k m:

Ratio of pressure fraction sustained by the liner(When design burst pressure is applied)

56

=

r
R

 =

dp
d

=

z
R

 =

d2
d 2

:

In-plane angle

e :In-plane parameter0 :Aperture ratio,  e , and  0 are shown in Figure 3.4.3-3.
Since equation (3.4.19) is an ordinary differential equation of the second order, thehead shape is determined by numerical calculations such as Runge -Kutta method.
The boundary conditions are assumed as the following at the joint of the head andthe shell.
 (ζ = 0) = 1,  (ζ = 0) = 0
When the head shape is determined, calculate the distribution of thickness of thecomposite material of the head using the following equation:cos0(3.4.21)t d =tcos wheret d :
 0:

Thickness of the composite material of the head
Winding angle at the joint of the head and the shell(2) Approach starting with head thickness calculation
This paragraph describes an example of determining the head thickness before
determining the shell thickness.
a. Head thickness determination
First, determine winding angle  for the helical winding layer (or in-plane winding
layer) after determining the winding pattern based on vessel shape. Applying thefollowing equations, calculate the thickness of the helical winding layer (or in-planewinding layer) and metallic liner.
t  = 1  k m 

tm 

PBD

(3.4.22)

4EL  LB  cos 2 

k mPBD
4Smy(3.4.23)57

wherekm:

Ratio of pressure fraction sustained by the head liner when thedesign burst pressure is applied

Determine the head shape and the distribution of the crossing angles of the fiberusing equations (3.4.19) and (3.4.20) and determine the distribution of the
thickness of the head using equation (3.4.21).
b. Shell thickness determination
Determine the thickness of a hoop winding layer of the shell using the following
equation:th =1  PBD- Smy t m - EL  LB  t  sin 2 EL  LBh  2(3.4.24)

Using the thickness determined in paragraphs a and b above, calculate the strainsof the helical winding layer and the hoop winding layer under autofrettage pressure.
 LP =

 PpD
1
- Smy t m 2
EL t  cos   4
(3.4.25)

 LPh 1  PpD Smy t m  EL  LP  t  sin 2 
EL t h  2
(3.4.26)

3.4.3.2 Confirming compressive strength of a metallic liner
When using a metallic liner, calculate the compressive stress of the unpressurized
liner after autofrettage and confirm that the liner will not yield due to compression.
S m0 <S’ mywhere
S m0 :

Stress of the liner under unpressurization after autofrettage

S’ my :

Yield stress of materials

When adopting a design method that allows for the metallic liner to yield, evaluate
its compressive strength according to the strength analysis described in paragraph3.5.1.
3.4.3.3 Confirming buckling strength of the metallic liner
When using a metallic liner, calculate the compressive stress of the pressuriz ed
liner after autofrettage and confirm that the liner does not buckle due tocompression.

58

S m0 < S cr
For stress in the circumferential direction of a cylindrical COPV (Source: NASACR-72753)
S cr
t 
= 106,000  m 
D
Em

3

(3.4.27)

For the head of a spherical and a cylindrical COPV (Source: NASA-CR-72753)





2

S cr
2 t 
= 21,200 1   m   m EmD(3.4.28)

where
Sm 0 :

Stress of the
autofrettage

metallic

liner

under

no

pressurization

after

S cr :

Buckling stressEm:

Modulus of longitudinal elasticity of the material of the metallic liner(Second modulus when the metallic liner is in yield range)tm:

Metallic liner sheet thickness

D:

Metallic liner diameterm:

Poisson ratio of the metallic liner

3.4.3.4 Drawing pressure-strain diagram
Calculate the ratio of pressure fractions to internal p ressure for the metallic linerand composite material based on the determined thickness and the shape of thevessel and draw the pressure-strain diagram (see example in Figure 3.4.3-4).

59

Set MEOP, Autofrettage Pressure, and Design Burst Pressure

Set Winding Method and Thickness

Compressive Yield Stress of Metal Liner

No

Judge

Allow Yield

No
Not Allow Yield

Yes

Confirm Metallic Liner Buckling Strength

No

Judge

Yes

Draw Pressure-strain Diagram

Perform Detailed Analysis

Figure 3.4.3-1 Thickness Determination Flow60

P

MeridianFigure 3.4.3-2 Symbols and Coordinates (1)

61





e

In-planesurface

Figure 3.4.3-3 Symbols and Coordinates (2)

62

1



(Metallic liner does not yield when used )(Metallic liner yields when used.)

Figure 3.4.3-4 Pressure-strain diagram (Representative examples)63

3.5 Detailed Analysis
Design of the high-pressure gas equipment shall be verified by stress analysis,verification of Leak-Before-Burst (LBB) occurrence, fatigue damage analysis or
flaw growth analysis, acceptance test, and qualification test as shown in Figure3.5-1. Select appropriate procedures depending on the results of the LBB
verification described below.
(1) LBB occurs and non-hazardous leakage(2) LBB does not occur, or LBB occurs and hazardous leakage
The design shall be verified by the general procedure described below.
1) Perform stress analysis to ensure the safety of the equipment according to themethods described in paragraph 3.5.1. Analysis of pressure vessels other thanlaunch vehicle propellant tanks shall follow paragraph 3.5.1.1, “Pressure load
analyses,” and paragraph 3.5.1.2, “Analysis for flight.” Analysis of launch vehicle
propellant tanks shall follow paragraph 3.5.1.2 “Analysis for flight” andparagraph 3.5.1.3 “Analysis for ground handling.”
2) LBB occurrence shall be judged by the following paragraph 3.5.2.
3) When LBB occurs and non-hazardous leakage is verified, perform fatigue
damage analysis to verify that the fatigue does not lead to burst, according toparagraph 3.5.3. For composite material and metallic liner that yields due topressurization or depressurization at MEOP of COPV, fatigue damage analysis
shall be performed regardless of LBB occurrence.
4) When LBB does not occur, or LBB occurs and hazardous leakage is verified,
perform flaw growth analysis according to paragraph 3.5.4.
5) Perform the pressure test and leak test as acceptance test according toparagraph 4.7.5.
When LBB does not occur, or LBB occurs and hazardous leakage is verified (orwhen the flaw growth analysis is performed even when LBB occurs and nonhazardous leakage is verified), the proof test (defect detection pressure test)
may be performed after pressure loading for the pressure test.
6) Qualification test shall be conducted according to paragraph 5.2.

64

Stress Analysis

Judge of LBB Occurren ce* 2(Analysis or Test)
LBB not occurred ,or Hazardous LBB
failure mode

Non-hazardous
LBB failure mode

Or

Fatigue life Analysis * 4(Analysis or Test)

Flaw Growth Analys is* 4(Analysis or Test)

Acceptance Test * 3

Acceptance Test * 3・ Proof pres s ure T es t
・ Leak T es t
*1・ Defect Detection Pressure Test

・ Proof Pres s ur e T es t
・ Leak T es t

Qualification Test
・ Vibration T es t
・ Pres s ure Cyc le T es t
・ Burs t Pres s ure T es t or Burs t T es t

Design Approval*1 Perform defect detection pressure test when the initial flaw size is not set at
nondestructive inspection.
*2 When LBB occurrence is not judged, it is assumed that LBB does not occur.
*3 Test items of acceptance test may be performed as a part of qualification test.
*4 Fatigue damage analysis shall be performed for composite material and yielding
metal liner of COPV whenever LBB occurs or LBB does not occur .

Figure 3.5-1 Method of Design Verification

65

3.5.1 Stress analysis
Conduct the following analyses to demonstrate that the thickness determinedaccording to paragraph 3.4 possesses appropriate strength (including buckling).
The analyses described in this paragraph are the minimum required. Conduct otheranalyses if considered necessary.
Determine the material properties and other mechanical or physical properties
used for stress analysis as below.
For metallic materials, select the appropriate values from the following documents
or material standards used (such as MIL, AMS, and F S standards).
(1) MMPDS-01

Metallic Materials and Elements for Aerospace Vehicle
Structure(2) AFML-TR-68-115

Aerospace Structural Metals Handbook

If a material not described in these official documents is to be used, conduct thematerial basic test specified in paragraph 5.1.1 and use its evaluation data. Notethat the material strength used as judgment criteria shall be equivalent to "A" valuein MMPDS-01.
This technical standard does not consider material creep since the equipment will
not be used at high temperatures as specified in paragraph 3.1.2.4, "Temperature
conditions. " For metal liners in composite pressure vessels, the yield stress of themetal liner material used for analysis of plastic deformation treatments can beanalyzed using the average value in a mill sheet for a similar commerciallyavailable material.
Conduct material basic test specified in paragraph 5.1.1 to obtain the evaluation
data on material properties and other mechanical or physical properties. Use theobtained evaluation data for composite material stress analysis.
The data shall be properly converted considering the volume fraction of fiber (V f )of composite materials. The tensile strength in the direction of the fiber shall be
the minimum value of the test data at 95% reliability and 1% destruction probability.
The modulus of elasticity in the direction of the fiber may be the fiber -producerprovided value with V f conversion applied, if the materials are a curing type andhave no distinct non-linearity.
For material properties of a non-metallic liner, conduct a material basic test
specified in paragraph 5.1.1, as necessary, and use the obtained evaluation data.
3.5.1.1 Pressure analysis(1) Purpose
These analyses confirm that thickness determined in paragraph 3.4 provide
appropriate strength (including buckling) for pressurization tasks including the66

following fabrication and launch preparation tasks.
a. Fabrication processb. Qualification testingc. Acceptance testingd. Leak tests during launch preparatione. System tests of a launch vehicle and payloads
f. Prelaunch pressurization
These analyses apply to metallic pressure vessels, COPV and p iping, fittings andother components which do not satisfy the safety factors shown in Table 3.1.3 -1.
They do not apply to launch vehicle propellant tanks because paragraph 3.5.1.3“Analysis for ground handling” covers pressure load analysis.
(2) Methods and conditions
a. Perform stress analysis of the thickness and shape determined in paragraph 3.4
using the Finite Element Method (FEM) analysis. Establish analysis conditions
properly (including model development) and clarify these conditions.
a. If required, perform buckling analysis of the thickness and shape determined inparagraph 3.4 in addition to stress analysis. Establish analysis conditions
properly (including model development) and clarify these conditions.
b. Perform FEM analysis primarily for elastic analysis. Consider geometric nonlinearity (form non-linearity) as necessary for COPV. Perform elasto-plasticity
analysis for plastic deformation and cases in which the metallic liner yields due
to pressurization to MEOP and depressurization. Properly develo p appropriate
models based on the necessary assumptions to ensure safety. For the metallic
liner thickness, use the minimum design metallic liner thickness for general parts
and weld parts. Also consider appropriate deformations such as weld
deformations (particularly, angular deformations) and mis-match. For structural
discontinuities including uneven surfaces and notches, determine the maximum
value of the local peak stress. If reliable analysis or experiment results areavailable for the stress concentration factor, use the result for peak stress. Whenthe stress concentration factor is not identified, use 4.
d. For buckling analysis, use the minimum design thickness. Consider a correction
factor for decrease in the buckling limit load caused by initial fabrication
irregularities and residual stress.
e. Establish boundary conditions including the spring constants based on thenecessary assumptions to ensure safety as in model development.
f. Consider MEOP for loading for a metallic pressure vessel.

67

g. Perform buckling analysis when applying vacuum to load propellants and theinternal pressure of the vessel becomes negative with respect to the externalpressure.
h. For loading conditions for COPV, perform the analysis considering all phasesfrom fabrication to operations and in the specified order for the vessels under
the following conditions.
1) When autofrettage is performed (only when autofrettage is performed).
2) When the vessel is not pressurized after autofrettage (only when autofrettage
is performed).
3) When proof pressure test is performed
4) When MEOP is being applied
5) When design burst pressure is appliedi. When analyzing the part where structure is discontinuous such place as near
the joint of head and cylinder of COPV, near the opening of head, where liner
thickness changes, or where pressure vessel is supported, pay particularattention to mesh division and similar occurrences.
j. For COPV, pay particular attention to where high stress and strain is applied,draw a pressure-strain diagram and analyze the case when a liner evaluated byMises equivalent stress does not yield in any of the following cases and the casewhen a liner yields.
1) When no pressure is applied after autofrettage
2) When the proof test pressure is applied
3) When no pressure is applied after the proof test pressure is applied
4) When MEOP is applied
5) When no pressure is applied after MEOP is applied.
k. For COPV, note that twisting or crossing of fiber caused by filament winding
reduces the composite material strength. Develop a model for FEM analysis forresin cracking, which is unique to COPV with filament windings by per forming
analysis with modulus of elasticity perpendicular to the fiber (E T ,  LT ) reduced towithin a range that will not disturb analysis at the elements whose stressperpendicular to the fiber and strain seemed to exceed material strength. Notethat the model may developed by performing alternative analysis with modulus
of elasticity perpendicular to the fiber reduced at all elements for convenience.
l. When external pressure is applied to metallic liner in COPV subjected to
autofrettage, perform buckling analysis. In this case, perform elasto -plasticity
analysis.

68

(3) Judgment criteria
Judgment shall follow paragraph 3.5.1.4.
3.5.1.2 Analyses for flight(1) Purpose
These analyses confirm that the thickness determined in paragraph 3.4 provide
appropriate strength (including buckling) for pressure loads and flight loads applied
to the equipment from launch to flight to the orbit (including retur n for the reusable
equipment).
The analyses shall apply to metallic pressure vessels, launch vehicle propellant
tanks and COPV. They shall also apply to piping, fittings, and other components
which cannot satisfy safety factors described in Table 3.1.3 -1.
(2) Methods and conditions
a. Perform stress analysis of the thickness and shape determined in paragraph 3.4
using FEM analysis. Establish analysis conditions properly (including model
development) and clarify these conditions.
b. When buckling analysis of the thickness and shape determined in paragraph 3.4
is required, perform it separately from stress analysis. Establish analysis
conditions properly (including model development) and clarify these conditions.
c. Perform FEM analysis primarily for elastic analysis. Perform elasto-plasticity
analysis when a metallic liner of a COPV yields due to pressurization to MEOP.
Develop appropriate models based on the necessary assumptions to ensure
safety. For the thickness, use the minimum design thickness for general parts
and weld parts. Also consider appropriate deformations such as weld
deformations (particularly, angular deformations) and mismatch. For structural
discontinuities including uneven surfaces and notches, determine the maximum
value of the local peak stress. If reliable analysis or experiment results areavailable for the stress concentration factor, use the result for peak stress. Whenthe stress concentration factor is not identified, use 4.
d. For buckling analysis, use the minimum sheet thickness in the schema tic. Also,
consider that initial irregularities and residual stress at the time of fabrication
will reduce the buckling load to below the theoretical value. However, forbuckling analysis of rocket propellant tanks, use the nominal design value as
the plate thickness.
e. Establish boundary conditions including spring constants based on thenecessary assumptions to ensure safety as in model development.
f. Each component shall be analyzed under the maximum stress condition during
flight sequence.

69

g. Calculate stress by numerical analyses including FEM when analyzing stress ofstructurally discontinuous parts such as joints of cylindrical shells and heads,
flanges and the like shown in Figure 3.5.1-1 and when analyzing stress of parts
simultaneously subject to flight load, pressure load, and thermal stress due tothe temperature distribution.
h. Conduct buckling analysis for the following cases.
1) When axial compressive force due to flight load and bending moment are
applied to the cylindrical shell.
2) When the payload load is applied to the head (dome). (See Figure 3.2-2.)
3) When back pressure is applied to the common bulkhead. (See Figure 3.2-2.)(3) Judgment criteria
Judgment criteria shall be followed by paragraph 3.5.1.4.
3.5.1.3 Analyses for ground handling(1) Purpose
These analyses confirm that the launch vehicle propellant tank thickness
determined in paragraph 3.4.2 provides appropriate strength (including buckling)for pressure loads during ground handling and ground handling loads.
(2) Methods and conditions
a. Calculate stress by numerical analyses including FEM when analyzing stress ofstructurally discontinuous parts such as joints of cylindrical shells and heads,
flanges and the like shown in Figure 3.5.1-1 and when analyzing stress of parts
simultaneously subject to ground handling loads, pressure loads, and thermal
stress due to the temperature distribution.
b. When buckling analysis of the thickness and shape calculated in paragraph 3.4
is required, perform buckling analysis separately from stress analysis. Set
analysis conditions properly (including model development) and clarify these
conditions.
c. Perform FEM analysis primarily for elastic analysis. Develop appropriate models
based on the necessary assumptions to ensure safety. For thickness, use th eminimum design metallic liner thickness for general parts and weld parts. Also
consider appropriate deformations such as weld deformations (particularly,
angular deformations) and miss-match. For structural discontinuities including
uneven surfaces and notches, determine the maximum value of the local peakstress. If reliable analysis or experiment results are available for the stressconcentration factor, use the result for the peak stress. When the stressconcentration factor is not identified, use 4.

70

d. When performing buckling analysis, use the nominal design thickness as the
thickness for calculating stress. Also, consider that initial irregularities andresidual stress at the time of fabrication will reduce the buckling stress to below
the theoretical value.
e. Establish boundary conditions including spring constants based on thenecessary assumptions to ensure safety as in model development.
f. For ground handling loads, consider special factor (see paragraph3.1.3.4).
g. Each component shall be analyzed under the maximum stress condition during
ground operations.
h. Conduct buckling analysis for the following cases.
1) When an axial compressive force due to the ground handling load andbending moment are applied to the cylindrical shell.
2) When the payload load is applied to the head (dome) (See Figure 3. 2-2.).
3) When back pressure is applied to the common bulkhead (See Figure 3.2 -2.).
(3) Judgment Criteria
Judgment criteria shall be followed by paragraph 3.5.1.4.

3.5.1.4 Judgment criteria
The following are the judgment criteria for “Pressure load analyses” in paragraph3.5.1.1, “Analyses for flight” in paragraph 3.5.1.2 and for “Analyses for groundhandling” in paragraph 3.5.1.3.
3.5.1.4.1 Judgment criteria for stress analysis for metallic pressure vessel andlaunch vehicle propellant tank
(1) Judgment criteria for strength analysis for metallic pressure vessels and launchvehicle propellant tanks
a. Primary general membrane stress, primary general membrane stress plus
bending stress, or primary local membrane stress plus bending stressStress intensity at any cross-section or parts to which pressure and externalloads such as vibration are applied shall be as illustrated in Figure 3.5.1 -2.
Figure 3.5.1-2 is a graphic representation of the following equation.
Pm  Pb 5 3  1 Pm    
Sm
3 2  3 Sm 

2

(3.5.1)

Pm  1Sm(3.5.2)71

In the above equation, P m + P b stands for general primary membrane stress plus
bending stress. P L + P b shall be used to calculate local primary membrane stressplus bending stress,
where
Pm :

Stress intensity of general primary membrane stress generated
by pressure analysis, analysis for flight and analysis for groundhandling.

Pm = Max{| 1 - 2 |,| 2 - 3 |,| 3 - 1|}
 1 , 2 , 3 : Principal stresses
Pb :Stress intensity of bending stress generated by pressure
analysis, analysis for flight, and analysis for ground handling

PL :Stress intensity of local primary membrane stress generated bypressure analysis, analysis for flight, and analysis for groundhandling

Sm :Design stress intensity  Material Yield Stress  y *  Safety Factor for Yield Stress * * 
S m  Small value among and
 Material Tensile Strength  u  * 
 Safety Factor for Ultimate * * 



*

Use the value specified at the design temperature. For materials used
at cryogenic temperatures, if the yield stress or tensile strength atcryogenic temperatures exceeds the yield stress or tensile strength at
normal temperature, the yield stress or tensile strength at normal
temperature may be used.

** Use the value which is specified in Table 3.1.3 -1 for pressure analysis,
and the value which is specified in Table 3.1.3-3 for analysis for flight.
Consider special factor shown in paragraph 3.1.3.4 and use the value
specified in Table 3.1.3-1 for analysis for ground handling.
b. Shakedown (Primary stress plus secondary stress)
One of the following conditions shall be satisfied at any cross -sections or parts
to which pressure and external loads such as vibration are applied.
P L + P b + Q  2 y

(3.5.3a)orP m + P b + Q  2 y

(3.5.3b)72

whereQ:

Secondary stress, excluding local stress concentration

 y:Yield stress of material(2) Judgment criteria for buckling analysis of metallic pressure vessels and launchvehicle propellant tanks
Based on the buckling analysis result, judge buckling using the following equations.

P
1
Sb
Sb 

(3.5.4)

Pcr
Safety Factor ** Use the safety factor which is specified in paragraph 3.1 .3.3 and isused.

actuallywhere

3.5.1.4.2

Sb:

Load display buckling strength

P:

Compressive load applied to the structure described above.

P cr :

Buckling limit load applied to the structure

Judgment criteria for stress analysis of COPV

(1) Judgment criteria for strength analysis of COPV
a. Judgment criteria for pressure analysis
The following are judgment criteria for composite materials, metallic liners andnon-metallic liners subjected to design burst pressure and proof test pressure
defined below.
(Design burst pressure)=(MEOP) x (Safety factor for design burst pressure
described in Table 3.1.3-2)(Proof test pressure)=(MEOP) x (Proof test pressure factor described in Table
4.4-1)
1) Composite materials- When design burst pressure is applied :S cb < S cu

where
S cb :

Maximum stress generated in composite material in the directionof the fiber due to design burst pressure.

S cu :

Tensile strength of composite material in the direction of the fiber.

73

S cu = S ca x R fw
S ca :

Minimum value of tensile strength of a composite material

R fw : The ratio at which strength of a composite material isreduced by overlap of fibers and other causes
When fatigue damage analysis (stress rupture analysis) shown in paragraph3.5.3.1 is conducted for the reusable type high-pressure gas equipmentusing glass fiber or other material, the following equation should be used:- When design burst pressure is applied :S cb < S cu x 0.625

2) Metallic liners
When a metallic liner does not yield- When proof test pressure is applied :S mp < S my

- Design burst pressure is applied : mb <  mu

where
S mp :

Miese equivalent stress generated in a metallic liner by proof test
pressure

S my :

Yield stress in a metallic liner mb :

Maximum strain generated in a metallic liner by design burst
pressure mu :Breaking strain in a metallic liner

When a metallic liner yields- When design burst pressure is applied: mb <  mu

Perform fatigue damage analysis and confirm that the strain generated in themetallic liner by MEOP described in the pressure-strain diagram will not
destroy the metallic liner by fatigue after being subjected to four times thenumber of pressurization cycles for the required l ife.
3) Non-metallic liners- When design burst pressure is applied: rb <  ru

where
 rb :

Maximum strain generated in a non-metallic liner by design burst
pressure ru :Breaking strain in a non-metallic linerb. Judgment criteria for analysis for flight74

1) Composite materials(S cm + S cd ) x (Safety factor for ultimate load specified in Table 3.1.3-4) < S cu
where
S cm + S cd :Maximum stress generated in a composite material in the
direction of the fiber by a combination of MEOP and dynamicload.

S cu :

Tensile strength of a composite material in the direction of
the fiber

When fatigue damage analysis (stress rupture analysis) is conducted pursuant
to paragraph 3.5.3.1 for expendable high-pressure gas equipment using glass
fiber or other material, the following equation should be used:(S cm + S cd ) x (Safety factor for ultimate load specified in Table 3.1.3-4) < S cu x
0.6252) Metallic liners(S mm + S md ) x (Safety factor for yield stress (metallic liner) specified in Table
3.1.3-4) < S my( mm + md ) x (Safety factor for ultimate load specified in Table 3.1.3-4) <  mu
where
S mm +S md :Mises equivalent stress generated in a metallic liner by a
combination of MEOP and dynamic load

S my :

Yield stress in a metallic liner

 mm :

Maximum strain generated in a metallic liner by the MEOP md :

Maximum strain generated in a metallic liner by dynamicloads

 mu :Breaking strain of a metallic liner

When adopting a design method that allows yielding of the metallic li ner,confirm only that the following strain conditions are satisfied:( mm +  md ) x (Safety factor for ultimate load specified in Table 3.1.3 -4) <  mu
3) Non-metallic liners( cm +  cd ) x (Safety factor for ultimate load specified in Table 3.1.3-4) <  cu
where
 cm +  cd :Maximum strain generated in a non-metallic liner by a
combination of MEOP and dynamic load75

 cu :Breaking strain in a non-metallic liner(2) Judgment criteria for buckling analysis of COPV.
Judgment criteria shall be followed by paragraph 3.4.3.3.
(3) Judgment criteria for compressive yield stress in composite pressure vessels
Judgment criteria shall be followed by paragraph 3.4.3.2. However, when design
method which allows yielding of metallic liner is adopted, this paragraph can be
exempted.

76

Neighboring
Structure
Head

Joint of cylindrical shell and head

Cylindrical shell

Figure 3.5.1-1 Joint Part of Cylindrical Shell and Head (Example)

77

2.0

Y = -1.5 X2 + X +1.5

Y =(P m + P b )/S m

1.5

1.0

0.5

0.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
X = Pm/Sm

Figure 3.5.1-2 Allowable range of primary general membrane stress, primary general membranestress plus bending stress, or primary local membrane stress plus bending stress783.5.2 Judgment of LBB occurrence (Analysis and testing)Judge by the following equations considering fracture toughness and plastic
collapse pressure or testing to determine whether LBB occurs due to cyclic loadingof the MEOP. The analysis shall be conducted for a part of high-pressure gas
equipment to which large stress is applied. However, the LBB analysis of thecylindrical pressure vessel shall target at the straight body.
The analysis shall be performed for pressure vessels and launch vehicle propellant
tanks. Additionally, the analysis shall be conducted for piping, fitting, and othercomponents which do not satisfy the safety factor requirements specified in Table
3.1.3-1.
3.5.2.1 Judgment of LBB occurrence by analysis
3.5.2.1.1 Metallic pressure vessel and launch vehicle propellant tank
Perform flaw growth analysis to estimate the surface flaw shape immediately
before penetration, or through-flaw dimensions immediately after penetration.
Evaluate the burst condition for either of the estimates following the steps below.
Flaw growth analysis may be substituted by evaluation using a wide range of
surface flaw shapes or through flaw dimensions.
1) Analyze the burst condition (K r ) in (1).
2) When the material has a noticeable burst resistance curve (R curve), analyze
burst condition (K R ) in (2) instead of burst condition (K r ) in (1).
3) Analyze plastic collapse condition (L r ) in (3).
4) Judge LBB occurrence in either of the following cases:
Judgment 1:

When K r <1 and L r <1, LBB occurrence is applied. In other cases,
LBB occurrence is not applied.

Judgment 2:

Judge by burst evaluation curve (Figure 3.5.2-1) considering
mutual influence between burst condition (K r ) and plastic
collapse condition (L r ).

The following are the details of LBB judgment equation.
(1) Burst conditions (K r )LBB occurrence is applied:K r 1

LBB occurrence is not applied:K r 1Kr =K
KC

K: Stress intensity factor

79

K c : Fracture toughness at material’s design temperature
The valve of K c shall be established based on highly reliable data obtained underappropriate test conditions. If the data reliability can be ensured, the mean valueof the data may be used.
The value of K should be calculated from (3.5.7) to (3.5.17). In case of using otherequations are used, the reference or the sources should be indicated clearly.
a. Surface flaw
K= a  m fm   b fb 

(3.5.7)2z    m   b 1 t 

(3.5.8)







2
24 
4




1
a
0.89  a 1
 a  a      0.5 
fmA .  0.18
   0.54  14 1      
113a  t
a c  t  
2c 
Q

0.2  0.65 







c
c
(3.5.9)
Q=   0.212   y 

2

2

a
 2  1  4.595   2c 

(3.5.10)

1.65(3.5.11)20 .5

 a   a 
fmB   11.  0.35     fmA
 t   c 






fbA  1    122.  0.24


(3.5.12)

0.75
1.5
2

a a

 a   A a
 a 
 0.55  105.  
 0.47    fm c
 c   t  
2c  2c (3.5.13)a a  a  
fbB  1  0.34  0.22    fmB
 t   2c  t

(3.5.14)1) Internal pressure of a cylindrical vessel (Flaw along axis)m PR, b  0t2) Internal pressure of a spherical vessel

m 

PR
,  02t b80

where:Linear stress distribution for thickness directionm :Tensile stressb :Bending stress y:

Yield stress at material set temperature

fm:

Correction factor of tensile stressf b:

Correction factor of bending stress

fmA :fm at point A (deepest point)

fbA :fb at point A (deepest point)

fmB :fm at point B (Surface point)

fbB :fb at point B (surface point)

Q:

Shape parameter of a flaw corrected for plastic region:Shape parameter of a flaw

2W: Sheet widtha:Flaw depthc:

One half of flaw lengtht:

Thicknessz:

Distance for thickness direction from inside (flaw side)

2h:

Sheet length

P:Internal pressure

R:

Internal radius

These equations shall be applied within the following range.

a  0.8,ta  0.5,2c2c  0.3,W2c  0.3
h

81

a
B
A

z
2W

2c

t

2h

b. Through-thickness flaw
K=σm √πaF(3.5.15)
2
2
3
2 4
F  1  7.2449  10   0.64856   0.2327   3.8154  10   2.3487  10 3 5(3.5.16)a(3.5.17)

Rt

where “a” is one half of the flaw length. The shape of a through-thickness flaw
is obtained by replacing the surface flaw that has penetrated thickness (flaw
depth a=t, flaw length 2c) with the through-thickness flaw (flaw length 2a=2c).
1) Internal pressure of a cylindrical vessel (Flaw in the axis direction)m  PRt2) Internal pressure of a spherical vesselm  PR
2t
These equations shall be applied within the following range.
05

82

a
2c

2a

t

t

(2) Burst condition ( K R )When the material has a noticeable burst resistance curve (R curve), thefollowing equations shall be applied.
LBB occurrence is applied

K dK R<
at K= K R
ada
LBB occurrence is not applied

dK R
K

a
da
KR:

at K= K R

Burst resistance at material’s design temperature(3) Plastic collapse conditions
LBB occurrence is applied

L r (local)1, L r (total)1or,

L r (local)1, L r (total)1
LBB occurrence is not applied

L r (total)1
Lr =

P
Pc

P:

Internal pressure

Pc:

Plastic collapse pressure at design temperature

83

The value of Pc should be calculated from (3.5.18) to (3.5.31). In case of using
other equations are used, the reference or the sources should be indicatedclearly.
a. Surface flaw
Local collapse
Pc = P0

  1


1 
1
m

(3.5.18)at(3.5.19)

 161. 1  c 2 m  1 

Rt



0 .5

(3.5.20)

Total collapse

Pc = P    1   
0
m 
 161
. c2 m   1 

Rt 


(3.5.21)0 .5(3.5.22)1) Internal pressure of cylindrical vessel ( Flaw in the axis direction)
P0 =

yt
R

2) Internal pressure of spherical vessel
P0 =2 y t
R

where
P0:

Plastic collapse pressure without a flaw

 y:

Yield stress at material’s design temperatureb. Through thickness flaw
Total collapse
1) Internal pressure of a cylindrical vessel (Flaw in the axis direction)

Pc 

P0
m

(3.5.23)

84

P0 

yt
R

(3.5.24)m  1 1.2987 2  0.026905 4  5.3549 x 10 4 6
 a
Rt



0.5

(3.5.25)(3.5.26)

where “a” is one half of the flaw length. The shape of a through-thickness flaw
is obtained by replacing the surface flaw that has penetrated thickness (flaw
depth a=t, flaw length 2c) with the through-thickness flaw (flaw length 2a=2c).
These equations apply for the following.
0   52) Internal pressure of spherical vessel
Pc  P02
8 2 
1 
 cos 2  

(3.5.27)0.5

2 y tR(3.5.28)

 aRt(3.5.29)

 aR(3.5.30)

P0 

where “a” is one half of the flaw length. The shape of a through-thickness flaw
is obtained by replacing the surface flaw that has penetrated thickness (flaw
depth a=t, and flaw length 2c) with the through-thickness flaw (flaw length
2a=2c).
These equations apply for the following.
t
 0.1
R

(3.5.31)(4) Burst evaluation curve
LBB occurrence is applied
Inside the burst evaluation curve.
LBB occurrence is not applied
Outside the burst evaluation curve.

85

The burst evaluation curve is expressed by the following equations.







K r  1  0.14 L r  0.3  0.7exp  0.65L r 

Lr  Lr

Lr

max

2

6



(3.5.32)max eff, y (3.5.33)

 eff, yy(3.5.34) y  u2

(3.5.35)

where
u :

Tensile strength at material’s design temperature

2.5
2.0

Kr

1.5

LBB occurrence is not applied.
1.0
0.5

LBB occurrence is applied.

0.0
M/標準

M/標準

M/標準

M/標準

M/標準

M/標準

Lr

Figure 3.5.2-1 Burst Evaluation Curve

3.5.2.1.2 COPV
(1) COPV with metallic liners
Evaluate burst condition (K r ) and plastic collapse condition (L r ) of a metallic linerwith the same method as described in paragraph 3.5.2.1.1 “Metallic pressure
vessels and launch vehicle propellant tanks.”

86

Verify the LBB occurrence for COPV according to 1) or 2) :1) K r <1, L r = random:K r 1, L r = random:

LBB occurrence is applied.
LBB occurrence is not applied.

2) Inside the burst evaluation curve:

LBB occurrence is applied.

Outside the burst evaluation curve:

LBB occurrence is not applied.

(2) COPV with non-metallic liners
All pressure fractions are shared by composite materials because a non -metallic
liner does not share pressure fractions. Ensure that composite material parts do
not burst due to fatigue damage analysis. For COPV, the LBB occurrence isassumed to be applied because bursting of the non-metallic liner does not induce
burst of the pressure vessel.

873.5.2.2 Judgment of LBB occurrence by test
3.5.2.2.1 Metallic pressure vessel (including launch vehicle propellant tank)
There are two methods to judge LBB occurrence by testing. Basically, the methodshould be selected using the flight model. In individual development project,however, the verification method may be selected by using test piece or equivalentas shown below, if test piece or partial model which has the same thickness as theflight model can generate stress or strain equivalent to that of flight model.
(1) Verification test using the flight modela. Test article
A vessel of the same structure as that for the flight model shall be fabricated in
the same manner.
Initial crack shall be determined by either of 1) or 2) below, with the crack width
being 0.3mm or less:
1) When flaw growth analysis is performed
The initial crack shall be the limit detectable in nondestructive inspection orlarger, and the shape of the initial crack (a/2c) shall be determined using either
the surface flaw shape immediately before the through thickness is reached or
the flaw dimension immediately after the through thickness is reached, as
estimated by flaw growth analysis.
2) When flaw growth analysis is not performed
The shape of the initial crack (a/2c = 0.1 ~ 0.5) shall be determined to cover alarger range of through thickness flaw dimensions.
b. Test method
To verify LBB occurrence by making an initial crack determined according to 1)or 2) in item a. above and applying a repeated load at MEOP.
c. Judgment criteria
Flaw shall be stable when the initial crack reaches through thickness.
(2) Verification test using test piecea. Test piece
Test piece shall be fabricated, welded, and applied heat treatment similarly toflight model and has the same thickness as specified in applicable drawing. An
example of the shape of the test article is shown in Fig.3.5.2 -2.
Initial crack shape shall be set by either of 1) or 2) in item a. of (1) verification
test using flight model, with the crack width of 0.3mm or less:88

Parallel
Part

Initial Crack

0.3 or less2cExpansion ofat

Figure.3.5.2-2 Shape of Test Article
b. Test method
Verify LBB occurrence by making initial crack set according to 1) or 2) in item a.
of (1) Verification test using the flight model and applying repeated stress or strain
equivalent at MEOP.
c. Judgment criteria
Flaw shall be stable when the initial crack reaches through thickness.
3.5.2.2.2 COPV
There are three methods to judge LBB occurrence by testing. Basically, it isdesirable to select the method using the flight model. In individual development
project, however, the verification method using partial model or test piece as shown
below, can be selected if partial model or test piece which has the same thickness
as flight model can generate stress or strain equivalent to that of flight model.
(1) COPV with metallic liners
a. The verification test using the flight model
1) Test article
The vessel of the structure same as flight model shall be fabricated by the sameprocess. Initial crack shall be set by either of 1) or 2) in item a. of (1) Verification
test using flight model for metallic pressure vessel, with the crack width of
0.3mm or less:892) Test method
To verify LBB occurrence by making initial crack set according to 1) or 2) in item
a. of (1) Verification test using flight model for metallic pressure vessel andapplying repeated pressure at MEOP.
3) Judgment criteria
Flaw shall be stable when initial crack reaches through thickness.
b. The verification test using partial model
1) Test article
Test article shall be partial model which simulates flight model in terms ofstructure.
Partial model of liner shall be fabricated, welded, and applied heat treatment
similarly to flight model and has the same thickness as specified in applicabledrawing. If the stress equivalent to Mises stress which is generated in flight
operation exceeds yield stress, strain cycle in flight operation shall be applied,
including the plastic zone for each of the tensile and compressive sides. An
example of the shape of partial model is shown in Figure 3.5.2-3.
Initial crack shall be set by either of 1) or 2) in item a. of (1) Verification test
using flight model for metallic pressure vessel, with the crack width of 0.3 mmor less:90

Note)

Both ends of the cylinder are fixed by jigs, and theload due to internal pressure is applied in the
direction of the hoop only.
t: Liner thickness simulates flight model
Initial Crack

Part CLiner

0.2 or less

0.3 or less

FRP
Hoop winding
Layer

Details of Part C (Example of Surface Crack)

Figure.3.5.2-3 An Example of a Test Article for a Partial Model

2) Test method
LBB occurrence shall be verified by applying a repeated load (pressure) to apartial model having an initial crack set as illustrated in Figure 3.5.2-3. Pressure
shall be set at the level where strain cycle in flight operation, including theplastic region for each of tensile and compressive sides, is equivalent to that offlight model. If strain is applied in the single axis direction for partial model,
magnitude of the applied strain is converted by the following equation.
Conversion equation:
’＝( 1 2 ＋ 1 2 ) 0.5
’： Strain to be applied to the partial model 1,  2 ： Strain to be generated in the flight model
3) Judgment criteria
Flaw shall be stable when the initial crack reaches through thickness.
c. Verification test using test piece91

The verification test using test piece as specified in item (2) for metallic pressure
vessels shall be applied. If Mises equivalent stress which is generated in flight
operation exceeds yield stress, test shall be conducted by strain control rather
than stress control. Stress shall be set at the level where a strain cycle in flight
operation, including the plastic zone for each of the tensile and compressive sides,
is equivalent to that of flight model.
(2) COPV with non-metallic liners
Test for COPV with non-metallic liners is not required because LBB occurrence forthese COPV is basically considered to be LBB occurrence is applied.

92

3.5.3 Fatigue damage analysis and test
Verify that high-pressure gas equipment has sufficient fatigue strength by analysis
or test.
3.5.3.1 Fatigue damage analysis(1) Purpose
Perform fatigue damage analysis for high-pressure gas equipment under cyclicloads, especially for the portions exposed to high stress, to analytically prove thatthe pressure cycle life requirement in (2) of paragraph 3.1.5 is satisfied.
This analysis shall be applied to pressure vessels and bellows (safety factor formaterial strength is specified in Table 3.1.3-1). Also, this analysis shall be applied
to pressure piping and fittings and other components which do not satisfy the safety
factor requirements specified in Table 3.1.3-1, No.3,4,7.
(2) Methods and conditions
a. The analysis shall confirm with Miner's Law (equation. (3.5.39)) according withthe (5) Judgment Criteria that the pressure cycle life requirement is satisf iedby comparing the cyclic stress amplitude for peak stress and the number ofloading cycles, which are calculated based on the equipment's duty cycle, withthe material's design fatigue curve.
b. When the cyclic stress is beyond the elastic range, evalua te cyclic strain (totalstrain amplitude) and calculate the value of the virtual elastic stress amplitudeat design temperature by multiplying the cyclic strain by the modulus oflongitudinal elasticity at design temperature.
b2. When average stress is applied, convert to equivalent stress amplitude by thefollowing SWT formula.
𝜎𝑎𝑒𝑞 = √𝜎𝑎 (𝜎𝑎 + 𝜎𝑚 )(3.3.35-2)

where







 aeq

:

equivalent stress amplitude when there is average stressa:stress amplitude

m:average stress ( m = 0 in case of compression)

For the applicable conditions of equation (3.5.35-2), refer to KHKS 0220 (2020).
c. When modulus of longitudinal elasticity shown in the material design fatigue
curve is different from the modulus of longitudinal elasticity at material designtemperature, correct the cyclic stress amplitude or virtual elastic stressamplitude by the ratio of longitudinal elasticity.

93

d. When the vibration stress which is generated by fluid pressure cycle andmechanical vibration is superimposed, fatigue due to pressure cycle andfatigue due to vibration are assumed to be added independently, and it shallbe evaluated by adding them as cumulative fatigue according to Miner’s Law(equation (3.5.39)).
e. The stress amplitude should take account of the environmental conditions
effect, for example, stress concentration due to the shape of corners, notches,
holes, joints, etc., finishing conditions such as surface roughness, temperature
in use and atmosphere.
(3) Optimum fatigue curve and design fatigue curve of metallic materials
a. KHKS method
Apply the optimum fatigue curve or design fatigue curve of KHKS 0220 (2020)
for the materials specified in this curve. In this case, the fatigue strength basedon the reliability of the optimum fatigue curve and the safety factor of fatigue
life are given. Therefore, it can be appropriately selected.
b. Fatigue test database issued by public institutions
Apply the reliable fatigue test database (MMPDS, "fatigue data sheet" and"space related material strength data sheet" issued by the National Institute forMaterials Science, etc.) for materials listed in above mentioned database.
c. Predicting fatigue curve
Apply the following modified Manson Equation to draw predicting fatigue curvefor low-cycle fatigue (less than 10 5 cycles) and for high-cycle fatigue (morethan about 10 5 cycles)Δ  0.0266  f 

0.155

 u 
E
 

0.53

N f 

 0.56 
 1.17  u 
E

0.832

Nf 0.09

Δ  EΔ t(3.5.36)(3.5.37)where t :

Total strain range (2 a ):Virtual elastic stress range (2 a )Nf:

LBB fatigue lifeE:

Modulus of the longitudinal elasticity at design temperatureu :Tensile stress at design temperature

f:Breaking strain at design temperature (true strain of fracture)94E,  u , and  f are determined by the material basic test specified in (1) ofparagraph 5.1 of this technical standard.
Draw the design fatigue curve so as to envelop the lower of the two curves
obtained by incorporating the safety factors of fatigue strength for a given
fatigue endurance [2] and of fatigue life [20] into the above equation. Thisequation is obtained by the strain-controlled alternating fatigue test (with 0mean stress), and the mean stress shall be compensated as needed.
d. Design fatigue curve development
Apply the modified Manson Equation in paragraph c. In addition, confirm
compatibility with the modified Manson Equation by conducting the straincontrolled alternating fatigue test using more than five test samples having
different total strain ranges. If compatibility is not ensured, determine theoptimum fatigue curve by performing the strain-controlled alternating fatigue
test using many test articles. Draw the design fatigue curve so as to envelop
the lower of the two curves obtained by incorporating the safety factors offatigue strength at a given fatigue endurance [2] and of fatigue life [20] into theabove equation.
(4) Composite Materials
a. Carbon fiber
Fatigue damage analysis (stress rupture analysis) is not required for carbon fiber.
b. Glass fiber and other
For glass fiber and similar materials, fatigue damage analysis (stress rupture
analysis) shall be performed and a material satisfying the following requirement
shall be selected:
Stress rupture strength of fthe flight operation period stress 0.625
Tensile strength of the fiber of a COPV Scu 

If glass fiber or other type of fiber, is demonstrated to have stress rupture
characteristics equivalent to carbon fiber, then it can be treated as equivalent
to carbon fiber.
(5) Judgment Criteria
The following Miner's equation shall be satisfied.
 ni  1.0
Ni(3.5.39)

where
Ni:

Number of allowable loading cycles corresponding to the cyclic stress95

amplitude  ai on the design fatigue curve. The stress intensity of thepeak stress for determining the cyclic stress amplitude shall be as
follows.
PL + Pb + Q + F
orPm + Pb + Q + F
where
F:

Increases in stress added to primary stress (P m , P L , P b ) andsecondary stress (Q) arising from stress concentrations due tostructural discontinuities such as steps or notches (peak stress).
This includes stress due to angular deformation and misalignmentof welds.

ni:

Number of loading cycles in the above respective stress amplitude

3.5.3.2 Fatigue damage test
Fabricate a test article (pressure vessel) geometrically similar to the flight vessel
subject to the test which contains a part to which cyclic load is applied and its
neighboring part which affects stress applied to the part. Conduct tests for fourtimes the number of required pressure cycles described in (2) of paragraph 3.1.5
to ensure bursting from fatigue will not occur during the required life. Correct theloading level considering the geometrical similarity between the flight vessel andthe test article.
JIS B 8266 Annex 8, “6. Experimental stress analysis”, ASME Section VIII Division
2 Appendix 6, etc., may be referred to regarding testing methods.

96

3.5.4 Flaw growth analysis and test
Conduct the following analyses or tests to confirm that the high-pressure gas
equipment, with a part to which high stress and cyclic load are applied, will last for
four or more times the required life specified in paragraph 3.1.5 “Life
Requirements”.
3.5.4.1 Flaw growth analysis
3.5.4.1.1 Purpose
Flaw growth analysis should analytically confirm that small flaws generated during
fabrication of high-pressure gas equipment will not grow to a size which causes
the equipment to fracture during the life specified in “Life requirements for pressure
cycle” in (2) of paragraph 3.1.5. This analysis shall apply to pressure vessels andto piping, fittings and other components which do not satisfy the safety factor
shown in Table 3.3-1. For COPV, this analysis shall apply only to metallic liners.
3.5.4.1.2 Methods and conditions
When conducting the analysis, clearly specify its analytical basis and scope. The
size of the initial flaw used for the analysis shall be determined as one of thefollowing:
1) Part on which nondestructive inspection is performed
The flaw size is detectable by nondestructive inspections, but minimum limit is2c = 0.25 [mm].
2) Part on which nondestructive inspection cannot be performed
The flaw size is ensured by proof test (defect detection pressure test), but
minimum limit is 2c = 0.25 [mm].
where the pressure used for defect detection pressure test shall be the pressure
to multiply proof factor by MEOP. Relation of the initial flaw size and proof factor
is expressed as follows.
ai =

acr
(P.F )2(3.5.40)

where
P.F: Proof factor
a cr :

Critical flaw size (depth) that results in destruction or through thickness penetration of high-pressure gas equipment when the
MEOP is applied.

ai:Size (depth) of initial flaw ensured by the proof test (defect detection

97

pressure test)
The flaw shape is defined in the following figure for calculating a cr and a i .
2cawhere a/c is determined by the fabrication process, loading conditions, etc.
(0.2  a/c  1) Conduct flaw growth analysis using the initial flaw size
determined above.
(1) Flaw growth rate equations
Flaw growth rate may be determined by Paris's Law or Forman's Law listed below.
If other equations are employed, clearly state their sources.
Material coefficients (C 1 , C 2 , m 1 , and m 2 ) shall be the values at normal temperature.
Fracture toughness (K c ) shall be the value at design temperature.
dam1
 C1 ΔK 
dN

da
dN

C2 ΔK (Paris)(3.5.41a)(Forman)(3.5.41b)m2

1 R1 K c  ΔK

where
a:

Flaw depth

N:

Number of loading cycles

K:

Fluctuation range of the stress intensity factor
K=K max -K min , However, K=K max , when K min is negative.

C 1 , C 2 : Material coefficients at normal temperature
m 1 , m 2 : Material coefficients at normal temperature
R1:

Stress ratio (R 1 = K min /K max )Kc:

Fracture toughness at design temperature

Choose the values for C, m and K c for the above equations based on highly reliabledata obtained under appropriate test conditions. If data reliability is ensured, themean of the data may be used.
(2) Stress intensity factor

98

Obtain stress intensity factors for calculating a cr , a i and the flaw growth rate withthe following equations. The following are the equations for the stress intensity
factor of a flat plate to which tensile and bending stress is applied (in paragraph a.
below) and the equations for the stress intensity factor of a cylindrical vessel (inparagraph b. below). These equations can also be used for the stress intensity
factor of a spherical vessel.
a. Stress intensity factor for a semi-ellipsoidal surface flaw on a flat plate
The stress intensity factor of a semi-ellipsoidal surface flaw on a flat plate, K I , iscalculated with the equations (3.5.7) to (3.5.14).
These equations consider plastic correction factors and can also be used whensmall-scale yielding conditions are not met.
b. Stress intensity factor in the axis direction for a semi-ellipsoidal surface flaw of
a cylindrical vessel.
The stress intensity factor in the axis direction for a semi -ellipsoidal surface flawof a cylindrical vessel, K I , is calculated with the following equations.
Internal pressure
Deepest pointK  = h t f

(3.5.42)22R o  + R i h = pR o 2  R i 2

(3.5.43)f  0.25 

0.4759   0.1262 ２ Ri 
0.102  t   0.02  (3.5.44)

0 .1

a
t

0.58
a
 
c

(3.5.45)

Surface point

K I = h t f s(3.5.46)
a 2

a 0.41

fs =f [1.06+0.28 ( t ) ] ( c )(3.5.47)

99

Random distribution stress
Deepest point 3

K I = t  i gi
 i=0




(3.5.48)

2

z
z
z
   0  1     2     3  
t
t
 
 
t

3

(3.5.49)

A   A    A    A    A    (3.5.50)
g A 
2

1

1

0

i

2

i

3

3

i

4

4

5

i

5



 Ri 
  0.02 0.102 
 t 



a
i  t 
a
 
c

i
0
0*
1
2
3

i

(3.5.51)

A0
0.00
0.20
0.00
0.00
0.00

A1
1.77670.50000.10450.02038
0.07283

A2-2.5975
0.09620.4189-0.00397-0.36006

A3
2.75200.000
0.000
0.42126
0.66883

A4-1.3237
0.000
0.000
0.000
0.000

A5
0.2363
0.000
0.000
0.000
0.000

*Applicable range a/c < 0.2,  >2

Surface point

 3

=

t
KI
 i gsi  i=0

(3.5.52)2
a  a 
gsi  gi  A 6  A 7     
 t    c 

(3.5.53)



i
0
1
2
3

A6
1.06
0.25
0.07
0.085


0.41
0.26
0.06
0.00

A7
0.28
0.20
0.16
0.02

where

100


0.58
0.58
0.22
0.10
0.05

A 0-7 : Constant for correction factorf:Correction factor at the deepest point (pressure)f s:Correction factor at a surface point (pressure)gi:

Correction factor at the deepest point (random distribution stress)(i = 0 to 3)

g si :

Correction factor at a surface point (random distribution stress) (i =0 to 3)KI:

Stress intensity factor

P:

Pressure

Ri:Internal radius of a cylinder

Ro:

Outer radius of a cylindert:

Plate thickness of a cylinderz:

Distance from inside (flaw side) in thickness direction:Non-linear stress distribution to the thickness direction(approximation of polynomial equations)h :Maximum value of hoop stress (circumferential stress)

i :Stress distribution with approximation of polynomial equations ( i = 0
to 3)

:

Parameter for flaw size ratio (internal pressure)i:Parameter for flaw size ratio (random distribution stress) (i=0 -3)

:Constant of parameter for flaw size ratio (random distribution stress):Constant for correction factor at a surface point (random distribution
stress)

These equations are applicable within the following ranges.
Internal pressure
0.05  a/t  0.85
0.1  a/c  1
0.2  1  R i /t  10
Random distribution stress
0.05  a/t  0.85

101

0.1  a/c  1
1  R i /t  10

Ri

t

Ro

2c
a

Z

To apply these equations, the following condition for small-scale yielding mustbe satisfied.

 a, t - a  2.5  KI  y 

2(3.5.54)

When the above equation is not satisfied, consider plastic region correction forthe stress intensity factor. Determine the plastic region correction either bysolving the following equation or by performing an iterative calculation.

*KI = f , a +

2
1  KI*  
2    y  (3.5.55)

where
*

KI :

Stress intensity factor corrected for the plastic region correctionf[ ]:Stress intensity factor equation (functional equation)

:Stressa:

Flaw size (flaw depth "a" or flaw length "c") y:Yield stress:Plastic constraint factor (deepest point =1.68, surface point =1)

3.5.4.1.3 Judgment criteria

102

The following equation shall be satisfied.
S.F 1 x N < N D(3.5.56)

where
S.F 1 :

Safety factor (S.F 1 = 4)N:

Number of loading cycles

ND:

Number of loading cycles until thru- thickness penetration or
unstable fracture of equipment results

3.5.4.2 Flaw growth test
(1) Purpose
Perform test to confirm that the high-pressure gas equipment satisfies the life
requirement by applying a cyclic stress equivalent to the stress described in (2) ofparagraph 3.1.5, “Life requirements for pressure cycle,” appli ed to the test article
simulating the flaw generated during fabrication.
(2) Methods and conditions
a. The initial flaw size shall exceed the detectable limit in the nondestructive
inspection, but the minimum size is 2c = 0.25 [mm]. The tip of the flaw shallhave fatigue damage.
b. Notch the test article on the surface. Ensure that the thickness of the test article
is that of the part subjected to the test as defined in the drawing. Simulate
processing, welding and heat treatment of a flight model.
c. The surface notch shape shall be 0.2  a/c  1.
d. Apply stress generated by the pressure cycle established in paragraph 3.1.5,“Life Requirements.”
e. Conduct the test at the design temperature established in paragraph 3.1.2.4,“Temperature conditions.”
f. Ensure that at least three test articles are available. Determine the number oftest articles based on the availability of the existing data, the test methods, etc.
(3) Judgment criteria
The tested item shall demonstrate four or more times the required life specified inparagraph (2) of 3.1.5, “Life requirements for pressure cycle.”1033.5.5 Stiffness analysis and test
Some properties of high-pressure gas equipment such as stiffness, mass, natural
frequency, sloshing behavior and so on are determined by analysis or testing andare provided to space system design for hazardous interaction control between
space system structure and high-pressure gas equipment. Confirmation of allproperties are under the tolerance required by space system may be alternative tothe presentation of analysis results.
3.5.6 Bellows analysis
The bellows No. 6 in Table 3.1.3-1 shall be analyzed as follows. The bellows No.5
in Table 3.1.3-1 shall be treated as a metal pressure vessel, and in addition to thebellows-related analysis, it shall also be analyzed as a metal pressure vessel.
3.5.6.1 Stress analysis and judgment criteria
Confirm that the stress values at MEOP and maximum displacement for all partsare under allowable stress by JIS B 8265 Annex N or JISB 8277 or finite element
method or equivalent methods. Analysis method and judging criteria for buckling
stress and torsional stress shall be EJMA 8th Edition for Unreinforced Bellows orequivalent and time-prove method.
For reinforced bellows such as the Braid type, use proven analysis formulas andcriteria. The material strength property evaluated with work -hardening which isused in the analysis needs that supporting evidence.
3.5.6.2 Life analysis and judgment criteria
Analysis method and judging criteria for the bellows shall be referred to JIS B 8265
Annex N or JIS B 8277 or paragraph 3.5.3.1 ”Fatigue damage analysis” orequivalent to these.
Displacement cycle shall be considered in the analysis. Additionally, if vibrationsuch as flow induced vibration, mechanical vibration and so on are overlapped on
the bellows operations, paragraph 3.5.3.1.(3)d of this standard shall be applied.
Analysis shall be performed using design fatigue curve without work hardening
effect. However, if reliable fatigue strength data of work hardening material areavailable, analysis can be performed using design fatigue curve with work
hardening effect.
3.5.6.3 Fluid vibration
Evaluate the possibility of fluid vibration induced inner flow of bellows by computer
analysis or flow testing. Prove that control capability of no resonance by computer
analysis in case of generating fluid vibration in bellows.

1043.5.6.4 Restriction of Bellows(1) Requirement
Bellows can deform flexibly within a limit of operation, but shall be restricted toprevent harmful deformation.
(2) Analysis method
Bellows shall be analyzed geometrically, kinematically, and mechanically.
(3) Judgment criteria
Bellows shall be restricted mechanically in the system. Failure prevention
measures such as bellows thrust compensation, prevention of deformation overthe limit, prevention of excessive reaction (including moment), prevention ofexcessive friction force at joint bearing, pressure change compensation of volume
change at expansion/compression, prevention of contamination and break down ofstraitening liner, and prevention of adherence caused by gas and the liquid freezing
shall be taken.

1053.6 Damage Control Requirements for COPVCOPV damage prevention control or damage tolerant desig n, or both shallbe implemented f or the expected t ype of damage. This provision covers three
types of damages, namely impact damag e, surf ace cut and abrasion.
Damage prevent ion control is an act of ensuring soundness and reliabilit y ofa product by taking appropr iate measures to prevent conceivable damage
and perf orming inspection to check the damage of product.
Damage tolerant design is an act of ensuring sound ness and reliabilit y of a
product by designing the product which does not lose f unctional
requirements due to conceivable damage.
In designing a pressure vessel, the t ype( s) of damage shall be identif ied andadequate damage control technique shall be decid ed.
Damage control is required f or COPV with the saf ety f actor for f racture ofless than 4.0 or thickness of less than 6. 35mm.
3.6.1 Damage prevention control
Damage prevention control of pressure vessel consists of development ofdamage prevention control plan, compliance wit h the plan, and record ofdamage prevent ion control.
3.6.1.1 Development of damage prevention control plan
To form an organization to implement damage prevention control and prepare
damage prevention control plan including the following:1) To identify all activities that may cause impact damage, surface cut, andabrasion in each process from acceptance inspection in 4.7.4 or reuseinspection in 6.1 to completion of the launch preparation work;2) To define damage prevention measures for any activity or work that may cause
damage;3) To define an effective method for protection of pressure vessels;
4) Damage prevention control process flow
Determine the timing and procedures according to the process flow of figure 3.6.11 for COPV damage inspection. Confirm damage by visual inspection, ultrasonicinspection, and acoustic emission (AE) measurements.
a. Visual inspections
Always perform visual inspections. Table 4.7.4-1 shows targets for visualinspections.

106

b. Ultrasonic inspections
If visual inspection uncovers any damage, perform ultrasonic inspection andconfirm any significant signals. In this case, demonstrate appropriate defectdetection capability and flaw detection procedures.
c. AE measurement
It is desirable to acquire AE data as much as possible in this flow. It is necessary
to show the correctness of AE measurement procedures.

3.6.1.2 Compliance with the damage prevention control plan and record ofdamage prevention control
Conduct damage prevention control activities in compliance with the damage
prevention control plan and record the damage prevention control.
Troubleshooting and other activities not included in the damage prevention control
plan shall be planned and conducted on the basis of evaluation of each ac tivity
and its interface with the damage prevention control plan.
3.6.1.3 Detection and judgment of damage
When damage is detected, it shall be inspected and inspection results shall berecorded, starting the nature of damage and circumstances surrounding thedamage in detail.
Based on the results of analysis or testing to assess the extent and degree ofdamage, it shall be decided whether the product can be used.
3.6.2 Damage tolerant design
Damage tolerant design, according to the type of damage, shall be specified withverification of its validity.
Validity of damage tolerant design shall be verified by analysis or testing. Pressure
vessel shall be designed and fabricated according to the identical specifications
applied to the flight model, shall be subjected to the severest level of damage inthe most sensitive position that is expected, and to a destructive test by applying
pressure, in order to check if it meets performance requirements.

1073.6.3 Consideration to damage control
For the damage prevention control and the damage tolerant design, the following
items shall be considered in the design.
a. Inclusion of protective layers.
b. Ensuring sufficient strength margins in design standard parts within ranges
allowed by the host system.
c. To provide design consideration to ensure that the standard design part does not
become a part susceptible to damage(Ex: When the CFRP hoop layer is the design standard, ensure that the outermost
layer does not become the hoop layer in the design.)

108

d. When thermal insulation is installed outside the container, consider design sizes,
thicknesses, ranges, etc., for the case of becoming a protective component.

109

4. Fabrication
Fabrication process of high-pressure gas equipment shall be assessed to besuitable through the trade-offs among reliability, work efficiency, costs, and others.
Mechanical processing, plate processing, welding, heat treatment, and ultrasoniccleansing shall not degrade the mechanical and physical properties of material tothe allowable limit. The manufacturing process shall guarantee the property ofmaterial used for design and analysis when high-pressure gas equipment is
manufactured.
Verify integrity of the following manufacturing methods by qualification test.
Integrity can be verified by development test, if development test is performed.
However, verify quality of flight model is assured in fabrication when material,
fabrication method, or fabrication facility is modified
Typical fabrication flows for high pressure equipment are shown in Figure 4-1(Metallic high-pressure gas equipment), Figure 4-2 (Composite pressure vessel)and Figure 4-3 (Piping assembly and propellant subsystem assembly) .
4.1 Fabrication and Forming
Fabrication method and forming method of high-pressure gas equipment influence
the mechanical properties of materials. Manage these methods according to thecriteria and provisions established by qualification test data.
4.2 Welding
For welding, select the appropriate welding methods, joint shapes, and filler
materials. Welding joints shall possess the specified mechanical properties.
4.2.1 General requirements(1) Locations, shapes, and dimensions of weld joints
Determine the appropriate locations, shapes, and dimensions of weld joints
considering strength deterioration in weld joints, scope of heat effect, stressconcentration, welding methods, etc.
(2) Increased weld thickness
When the strength of weld joints becomes lower than that of the base material,consider reducing the strength of weld parts. If necessary, increase the thicknessof the weld joints as shown in Figure 4.2-1.
(3) Welders
Welders shall be certified as specified in AWS D17.1 or shall possess equivalentqualifications.
(4) Inspection of welding machines110Periodically inspect each different model of the welding machines to maintainwelding performance. Based on the inspection, judge the welding machines’
performance and stability.
(5) Groove shape
Grooves for high-pressure gas equipment shall conform to proven shapes unlessspecifically instructed otherwise. A representative set of the groove shapes isshown in Figure 4.2-2.
(6) Repair welding
When performing repair welding, generally weld the same weld part once or twice.
4.2.2 Welding control
Control welding by preparing the welding procedural document. Pay particularattention to the following items which affect strength.
(1) Welding Conditions
Ensure the welding conditions satisfy paragraph 5.1.2, “Welding method selection
and verification.” Document the actual welding conditions. Contr ol atmosphere andwelding machines during actual welding and maintain reproducibility of the above
conditions.
(2) Grooves
Confirm the cleanliness of the grooves before welding to ensure removal of greaseor rust which affects weld strength.
(3) Preventing welding deformation and unevenness
Minimize welding deformations (particularly angular deformation) and mis -matchby setting welding joints on the appropriate welding jigs.
(4) Weld beads and penetration beads
Establish the welding conditions so that weld beads and penetration beads becomesmooth to avoid stress concentration. When penetration beads cannot be identified,confirm them by conducting a development test or qualification test.
(5) Preventing missing targets
Weld correctly on the targeted weld lines.
(6) Weld defects
Establish the welding conditions so that surface and internal defects of the weld
parts are within the specified values.

111

Para. 4.7.1.1

Material Acceptance Inspection・ Acceptance inspection

Para. 4.1

Processing and Forming・ Shell Processing
・ Boss Processing
・ Port Processing

Para. 4.3

Heat Treatment

Para. 4.7.2

Parts Inspection
・ Dimension Inspection
・ Visual Inspection
・ Nondestructive Inspection

Para. 4.2

W elding

Para. 4.3

Heat Treatment

Para. 4.7.3

W eld Parts Inspection
・ Visual Inspection
・ Nondestructive Inspection

Para. 4.7.4

Acceptance Inspection
・ Dimension Inspection
・ Visual Inspection
・ Volume Inspection・ Mass Inspection
・ Cleanliness inspection

Para. 4.7.5

Acceptance Test
・ Proof Pressure Test
・ Def ect Detection Pressure Test
・ Leak Test

Figure 4-1 Metallic High-pressure Vessel Fabrication Flow
(Typical Example)

112

Composite Material

Metallic Liner
Para. 4.7.1.1

Material Acceptance Inspection

Composite Material
Acceptance Inspection

・Acceptance Inspection

Para. 4.1

Processing and Forming

・Acceptance Inspection

・Shell Processing
・Boss Processing
・Port Processing

Para. 4.3

Heat Treatment

Para. 4.7.2

Parts Inspection

Para. 4.7.1.2

・Dimension Inspection
・Visual Inpsection
・Nondestructive Inspection

Para. 4.2

WeldingPara. 4.3

Heat Treatment

Para. 4.7.3

Weld Parts Inspection
・Visual Inpsection
・Nondestructive Inspection

Para. 4.7.1.1

Metallic Liner Acceptance
InspectionInspection
・Dimension
・Visual Inpsection
・Volume Inspection
・Mass Inpsection
・Cleanliness inspection

Para. 4.7.5.2.1

Metalllic Liner Acceptance Test
・Proof pressure test
・External inspection or ・Proof test
・Internal inspection
・Leak test

Para. 4.5

Filament Winding

Para. 4.5

Resin CuringPara. 4.6

Autofrettage

Para. 4.7.4

Composite Pressure Vessel Acceptance Inspection
・Dimension Inspection
・Visual Inspection
・Mass Inspection
・Volume Inspection
・Cleanliness Inspection

Para. 4.7.5.2.2

COPV Acceptance Test
・Proof Pressure Test
・Leak Test

Figure 4-2 (1/2) COPV Fabrication flow (Typical Flow for Vessels with
Metallic Liners)

113

Composite Material

Material Acceptance
Inspection

Mandrel Preparation

Para. 4.7.1.2

・Acceptance
Inspection

Para. 4.5

Rubber Liner

Filament Winding

Material Acceptance
Inspection
Para. 4.5

Resin CuringPara. 4.4

Rubber Liner Forming

Para. 4.7.4

COPV Acceptance Inspection

Para. 4.7.1.3

・Acceptance
Inspection

・Dimension Inspection
・Visual Inspection
・Mass Inspection
・Volume Inspection
・Cleanliness Inspection
Para. 4.7.5.2.2

COPV Acceptance Test
・Proof pressure Test
・Leak Test

Figure 4-2 (2/2) COPV Fabrication Flow (Typical Flow for Vessels with Rubber
Liners)114

Piping and Fitting

Para 4.7.1.1

Components

Propellant Tank

Material Acceptance Inspection- Acceptance Inspection

Para 4.2

Para 4.7.3

Welding

Welded Part Inspection(Piping Assembling)- Visual Inspection- Nondestructive Inspection

Para 4.2

Welding

Welded Part
Inspection(Propellant- Visual Inspection

Para 4.7.3- Nondestructive Inspection
Propellant Subsystem
Acceptance Test
- Proof Pressure Test

Para 4.7.5- Leak Test

Figure 4-3 Piping Assembly and Propellant Subsystem fabrication Flow
(Typical Example)

115

For Metallic Pressure Vessels

(i)

(ii)

(iii)

For COPV
Metallic Liner Outer Surface

Metallic Liner Inner Surface

Figure 4.2-1 Typical forms of welded joint thickening (reference)116

U Shape

Butt Joint(Without Filler Material)

U Shape with Backing

V Shape

H ShapeFigure 4.2-2 Representative Set of Groove Shapes for High-Pressure Gas
Equipment (Reference)1174.3 Heat Treatment
Apply appropriate heat treatments such as annealing, post-welding heat treatment,
solution heat treatment, and aging during the high-pressure gas equipment
fabrication process except when heat treatment is expected to deform the structure,
as in weld joints of thin vessels and heat treatment is considered inappropriate.
4.4 Non-metallic Liner Forming
Control the following items appropriately when non-metallic liner is formed.
a. Useful life of raw materials
b. Useful life of adhesive, if adhesive is usedc. Formulation ingredients ratio of adhesive, if adhesive is used
d. Temperature and pressure profiles of autoclave, if heat curing is performed
4.5 Filament Winding
When performing filament winding using composite material, control the following
items according to the criterion which are specified in paragraph 5.1.3, “Prototype
Test.”(1) For winding processes
a. Control of useful life of fibers and matrix resinsb. Winding angles of fibers in each layerc. Number of windings or weight of fibers used
d. Fiber tension during windinge. Matrix resin formulation ingredients ratio (when two or more resins are mixed)
f. Matrix resin temperature during winding
g. Volume fraction of fiber (V f )h. Winding speed(2) For curing processes
a. Temperature and pressure profiles of autoclave if heat curing is

performed

b. Time for curing if performed
4.6 Autofrettage
When autofrettage is performed on a metallic liner by applying internal pressure
after composite materials are formed, ensure the following requirements fordetermining processing pressure are satisfied.

118

a. Perform autofrettage at around 100 to 110% of the proof test pressureestablished for COPV. (Using Figure3.4.3-4 as an example, performpressurization following the line connecting 0, T0, and T1.)
b. Fluids used for autofrettage should be incompressible.
c. Confirm buckling of a metallic liner by evaluating appearance, capacity,
dimensions, and other inspection results.
d. When performing autofrettage, observe safety standards applied to proof
pressure tests on incompressible fluids.
4.7 Inspection and Test
Inspections and tests for high-pressure gas equipment shall be highly reliable andsuitable for the inspection or test purpose and inspection or test targets. The
processes and methods should not degrade equipment quality.
During the high-pressure gas equipment fabrication, conduct the following
inspections and tests and document their results.
4.7.1 Material acceptance inspection
4.7.1.1 Metallic material acceptance inspection
Confirm that the properties of accepted materials satisfy the specifications by using
mill sheets, etc.
4.7.1.2 Composite material acceptance inspection
Confirm that the following properties of accepted composite materials satisfy therequirements based on the inspection records and other related matters.
(1) Fibers
a. Fiber brand names
b. Tensile strength as a fiberc. Modulus of elasticity as a fiberd. Breaking strain
e. Usage expiration datef. Other properties required for their design and fabrication(2) Matrix resin (when accepted alone)a. Resin brand nameb. Components

119c. Viscosity
d. Usage expiration datee. Other properties required for their design and fabrication(3) Matrix resin (when accepted as pre-preg)a. Resin brand nameb. Glass transition temperaturec. Resin content
d. Gel timee. Resin run-off
f. Usage expiration dateg. Other properties required for their design and fabrication
4.7.1.3 Non-metallic liner acceptance inspection
Confirm that the following properties of accepted non-metallic liners satisfy therequirements based on the inspection records and other related matters.
(1) Unvulcanized rubber
a. Appearance
b. Dimensions(2) During and after vulcanization
a. Density
b. Viscosity during vulcanizationc. Hardness after vulcanizationd. Breaking strain after vulcanizatione. Other properties required for their design and fabrication(3) Adhesives (when used)
a. Adhesive brand names
b. Other properties required for their design and fabrication
4.7.2 Parts inspection (Metallic material)(1) Dimension inspections
Confirm that drawing requirements are satisfied.

120

(2) Visual inspections
Confirm that no harmful processing damage, dents, or corrosion exist.
(3) Nondestructive inspections
Perform penetrant testing, eddy current testing, or ultrasonic inspection to confirm
that there are no harmful defects. The defect detection capability specified forthese penetrant inspections means the size of the defects detectable bynondestructive inspection defined in 1) of paragraph 3.5.4.1.2.
a. Penetrant testing
When performing penetrant testing, adhere to the testing standards specified in
AMS-2645, ASTM-E1417, or the equivalent.
b. Eddy current testing
When performing eddy current testing, demonstrate appropriate defect detection
capabilities and flaw detection procedures.
c. Ultrasonic testing
When performing ultrasonic inspection, demonstrate appropriate defect detection
capabilities and flaw detection procedures.
If the above nondestructive inspections are not applicable due to item shape, thenselect and implement an appropriate alternative method with sufficient defectdetection capabilities.
4.7.3 Welded part inspection
4.7.3.1 Welding condition
Confirm that welding is performed according to the conditions specified byparagraph 4.2.
4.7.3.2 Visual inspection
Confirm that welding locations are as specified in the drawings. Confirm also thatweld reinforcement shape and such are appropriate.
4.7.3.3 Welding deformation and mis-match
Confirm that welding deformation and mis-match are within drawing requirements.
4.7.3.4 Welding bead and penetration beadConfirm that the shapes of welding beads and penetration beads are within drawing
requirements. Generally, confirm penetration bead by visual inspections.

121

4.7.3.5 Weld defect(1) For surfaces
Perform penetrant testing, eddy current testing, or ultrasonic inspection inconsideration of item form, workability, etc. The defect detection capability
specified for these penetrant inspections means the size of the defects detectableby nondestructive inspection defined in 1) of paragraph 3.5.4.1.2. If this inspection
does not reveal harmful defects, a proof test may be omitted.
a. Penetrant testing
Perform penetrant testing in adherence to the testing standards specified in AMS 2645, ASTM-E1417, or the equivalent to confirm there are no harmful defects.
b. Eddy current testing
Perform eddy current testing to confirm there are no harmful defects. When
applying eddy current testing, demonstrate that defect detection capabilities andtest procedures are appropriate.
c. Ultrasonic inspection
Perform ultrasonic inspection to confirm there are no harmful defects. When
applying ultrasonic inspection, demonstrate that defect detection capabilities andtest procedures are appropriate.
(2) For inside
Conduct radiographic testing or ultrasonic flaw detection testing in considerationof item shape, etc.
a. Radiographic testing
Perform radiographic testing in adherence to ASTM-E1742 or equivalent
standards to confirm the absence of harmful unwelded areas, cracks, porosity,and poor fusion. When performing radiographic testing, imaging plates (IP) canbe used.
The criterion for determining the size of a single porosity shall be determined with
sufficient design consideration, taking the least of the following as the maximum
limit:
・The smaller of 1/3 × t (thickness) or 1.5 mm, as defined in AWS D17.1 CLASS A
or NAS 1514 CLASS III.
・Initial defect size in paragraph 3.5.4.1.2.
For multiple porosities, one of the following must be satisfied:122

・ The sum of the maximum dimensions of welded parts per 76 -mm length is
the smaller of 1.33 x t (mm) or 6 mm or less, in compliance with AWS D17.1
CLASS A.
・ The total area per 25-mm length of the weld is 1.25 x t (mm2) or less, incompliance with NAS 1514 CLASS III.
Note that t may be the actual weld thickness.

b. Ultrasonic testing
Perform ultrasonic inspection in adherence to ASTM-E164 or equivalent
standards to confirm there are no harmful unwelded areas, cracks, porosity, orpoor fusion.
The criterion for determining the size of a single porosity shall be determined with
sufficient design consideration, taking the least of the following as the maximum
limit:
・The smaller of 1/3 × t (thickness) or 1.5 mm, as defined in AWS D17.1 CLASS A
or NAS 1514 CLASS III.
・Initial defect size in paragraph 3.5.4.1.2.
For multiple porosities, the sum of the maximum dimensions of welded parts per
76-mm length is the smaller of 1.33 x t (mm) or 6 mm or less, in compliance withAWS D17.1 CLASS A.
Note that t may be the actual weld thickness.
If ultrasonic inspection detects and measures porosity, demonstrate the flaw
detection procedure, detection capabilities, and capabilities for dimensional
measurements.

1234.7.4 Acceptance inspection(1) Dimension inspection
Confirm that drawing requirements are satisfied.
(2) Visual inspection
Make clear the acceptance criteria. Perform visual inspection items 1–6 listed inTable 4.7.4-1 for metal pressure vessels, and items 1–12 for COPV, satisfying all
criteria. Confirm that the requirements for COPV as shown table4.7-1 No.1 toNo.12 are satisfied by performing visual inspections. The inspection scope shallbe classified macro inspection by direct visual inspection from micro inspection
using microscope.

Table 4.7.4-1 Visual inspection items
General inspection items for metallic pressure
vessel and COPV
1

Machining print

2

Impact print/Pressed print

3

Friction defect4

Abnormal color tone

5

Corrosion

6

Scaffolding

Additional inspection items for COPV
7

Exfoliation

8

Breaking of fiber

9

Abnormal order of fiber/Pucker

10

Resin crack

11

Resin absence/Resin excess

12

Contamination/Bubble

Notice: Inspector’s eyesight and lightning condition for inspection shall becomplied with NDIS 3414” Standard of visual testing” established by theJapanese Society for Non-Destructive Inspection.

(3) Volume inspection
Confirm that the requirements are satisfied by performing volume inspection asnecessary.

124

(4) Mass inspection
Confirm that the requirements are satisfied by performin g mass inspections asnecessary.
(5) Cleanliness inspection
Confirm that the requirements are satisfied by performing cleanliness inspection
for space system specification.
4.7.5 Acceptance test
4.7.5.1 Metallic high-pressure gas equipment acceptance test
Conduct the following tests on metallic high-pressure gas equipment whose
fabrication has been completed.
(1) Proof pressure test
a. Proof pressure testing pressure is that obtained by multiplying the maximum
expected operating pressure (limit pressure) by the coefficient in Table 4.4-1. In
principle, the range for stress intensity during proof pressure testing must be within
the range shown in Figure 4.4-1.
b. When conducting proof pressure testing at room temperature, in principle, correct
the testing pressure according to the ratio between the material yield stress at thedesign temperature and the yield stress at room temperature.
(Proof test pressure at normal temperature) =(Proof test pressure at design temperature) ×(Yield stress at normal temperature)(Yield stress at design temperature)c. Figure 4.4-1 graphically represents the following equation.
Pm + Pb 5 3  1 Pm 
= -  3 2  3 Sm y2(4.7.1)

Pm  1(4.7.2)yIn the above equation, P m + P b stands for general primary membrane stress plus
bending stress. Calculate local primary membrane stress plus bending stressusing P L + P b ,
where
Pm:

Stress intensity of general primary membrane stress

125

PL:

Stress intensity of local primary membrane stress

Pb:

Stress intensity of bending stress y:

Yield stress of material

Stress strength at the time of proof pressure testing on launch vehicle propellant
tanks shall satisfy the following shakedown requirements for any cross -section orpart, in addition to equations 4.7.1 and 4.7.2:
PL＋Pb＋Q  2yor
Pm＋Pb＋Q  2y
where
Q:

Secondary stress, excluding local stress concentration

 y:Yield stress of the materiald. Fluids used for the proof test should be incompressible fluids. However,compressible fluids may be used when incompressible fluids are judged
inappropriate due to the properties of high-pressure gas equipment.
e. After testing, perform visual inspections of the exterior and confirm there are noharmful deformations, cracking, or other abnormalities.
f. In separate testing of high-pressure gas equipment, except for rocket propellant
tanks, after proof pressure testing, in principle perform one of a. penetran t
testing, b. eddy current testing, or c. ultrasonic inspection in paragraph4.7.3.5(1) on welded parts and ensure there are no harmful defects.
g. To verify prescribed pressure was loaded.
h. In principle, measure cylindrical part diameters before and after proof pressure
testing, and confirm that residual deformation is 0.2% or less.
i. (Deleted)j. If components are installed on the equipment with gasket, the blank flange andthe dummy gasket which is more robust than the actual one could be installed
instead of the actual components for the proof pressure test.
Note that there are exceptions to the principles in items a, b, f, and h, including
piping to which exemption item 2.2.1 applies and purchased goods to which item
2.2.3 applies.
(2) Leak tests
a. Complete proof pressure tests prior to leak tests.

126

b. For a leak test, use a pressure with gas at the MEOP or higher. For launchvehicle propellant tanks, apply the equation below for leak test.
(Leak test pressure at normal temperature) ≦1/4 x (Design burst pressure atdesign temperature) x (Tensile strength at normal temperature) / (Tensile
strength at design temperature)c. Gas used for a leak test shall not degrade performance of pressure vessels.
d. Determine the time for pressurization to suit the individua l leak test method.
e. Leakage shall be within the specified values.
(3) Defect detection pressure tests
Perform assurance testing for areas where the nondestructive inspections
described in 3.5.4.1.2 cannot be performed as follows.
a. For pressure for defect detection pressure test, use the MEOP multiplied byproof factors obtained according to paragraph 3.5.4.1.2. The range of stressstrength at the time of defect detection pressure test shall be as specified in (1)of paragraph 4.7.5.1, “Proof pressure tests.”b. A defect detection pressure test may be conducted immediately following a proof
pressure test.
c. A defect detection pressure test should be conducted using incompressible
fluids. Try to hold the pressure for 5 seconds or less and try to depressurize tothe proof test pressure level within 15 seconds or less after pressure is achieved(see Figure 4.7-2).
d. After testing, perform visual inspections of the exterior and confirm there arethat no harmful deformations, cracking, or other abnormalities.
e. After assurance testing (defect detection pressure testing), perform one of a.
penetrant testing, b. eddy current testing, or c. ultrasonic inspection inparagraph 4.7.3.5(1) on welded parts and ensure there are no harmful defects.
f. When the same pressure is used for the proof test and the detect detection
pressure test and the two tests are conducted simultaneously, verify prescribedpressure was loaded.
g. For additional information on the defect detection pressure test, refer to NASA
SP-8040.
4.7.5.2 COPV acceptance test
4.7.5.2.1 Metallic liner acceptance test
For the metal liner in full-wrap containers and the straight body in hoop-wrap
containers, confirm that there are no harmful defects on the outer or inner surfaces

127before filament winding.
Alternatively, perform (1) proof pressure testing, (2) airtightness testing, and (3)assurance testing (if required) in paragraph 4.7.5.1 on individual liners. Here, theproof pressure testing pressure and airtightness testing pressure should be thepressure set for the metal liner alone.
4.7.5.2.2 COPV acceptance test
(1) Proof pressure test
Conduct proof pressure tests according to (1) of paragraph 4.7.5.1. However,paragraphs b, c and f shall not apply.
Proof pressure tests may be conducted simultaneously with pressurization
specified in paragraph 4.6, “Autofrettage.”(2) Leak test
Conduct leak tests according to (2) of paragraph 4.7.5.1.

128

Table 4.7-2 Factors Used to Multiply MEOP to Obtain Proof Test Pressure
No.
Structural Category

Factor

Metallic Pressure Vessels and
COPV(Approach allowed)

1.5 or more

Metallic Pressure Vessels(Approach prohibited)1 (saftety factor for tensile strengt)
or more2

COPV(Approach prohibited)1 (saftety factor for burst pressure)or more2(Note 1)
1

2

Piping and Fittings3

1.5 or more
(Diameter 38.1mm or more)
Piping and Fittings

4

1.5 or more
(Diameter less than 38.1mm)

5Bellows

1.0 or more

6

Bellows

1.5 or more

7

Other Components

1.5 or more

8

Launch Vehicle Propellant
Tanks

1.0 or more

Note 1 When selecting a coefficient from this table, match the number in this table andthe numbers in Table 3.1.3-1 and Table 3.1.3-2 and select a coefficient allowing theapproach of personnel.

129Collapse limit for the combination of
membrane stress and bending stress *2

2.0
Y = -1.5 X2 + X +1.5

Y =(P m + P b )/ y

1.5

Y=2.15-1.2X(1.5×0.9=1.35)(1.35)

1.0
Allowable limit for
Proof Pressure Test *1

0.5

pressure
0.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
X = Pm/y*1: Allowable limit of metallic pressure vessels during proof pressure test.
*2: Allowable limit of launch vehicle propellant tank during proof pressure test.

Figure 4.7-1

Stress Intensity Allowable Limit during Proof Pressure Test

130

15 Seconds or Less

Pressure
5 Seconds or Less
Defect Detection Pressure Test
Proof Test Pressure
Leak Test
Pressure(MEOP)

Time

Figure 4.7-2 Defect Detection Pressure Test Time Constraints

131

5. Development Test and Qualification Test
5.1 Development Test
5.1.1 Material basic test
(1) Metals
a. When fabricating high-pressure gas equipment with a safety factor below 3.5
using non-AMS, MIL, or FS standard materials, or when manufacturing high pressure gas equipment using a newly developed processing method, test as
necessary and obtain the following material data:- Chemical composition- Macro/micro metallographic structure- Tensile strength, yielding stress, and elongation (including weld parts)- Fracture toughness- Fatigue properties
b. Test article shapes shall meet JIS or ASTM standards. If test article shapes do
not satisfy JIS and ASTM, clearly state the shapes.
c. Evaluate the obtained data according to MMPDS-01.
(2) Non-metals and composite materials
a. When a non-metallic liner is fabricated, conduct a tensile test as necessary toobtain material data including breaking strain ( ). For vulcanized rubber,conduct a tensile test according to JIS-K6251, “Rubber, vulcanized or
thermoplastics-Determination of tensile stress-strain properties”. If the test is
conducted according to other standard, clearly describe the test method.
b. Data of tensile strength in the direction of fiber must be acquired. The test
method and test piece shape shall satisfy ASTM D2290, ASTM D3039. If thetest piece shape does not satisfy ASTM standard, clarify the test piece shapeand validity of the acquired data. The test piece must be fabricated in the sameprocess as the final product fabrication process.
c. Test the following properties as necessary to obtain the material data.
- Elasticity factor (Obtain material data for the elasticity factor in the directionof fibers according to paragraph 3.5.1.)- Stress rupture characteristics- Ionized radiation susceptibility
d. Materials for which sufficient data has already been acquired need not be
conducted material basic test.

132

5.1.2 Welding method selection and verification
Select the welding method which ensures the weld quality required in paragraph4.2, and verify the selected method. When selecting a welding method to be used,clarify the following and ensure reproducibility.
a. Welding methodsb. Welding materials (chemical composition, trade name, diameter of welding
rods, etc.)
c. Welding conditions (electrode, welding current, arc voltage, welding speed,
welding position, welding rod manipulation method, welding heat input, gas
shielding, etc.)
d. Backing
e. Preheating
f. Post welding heat treatment
Verify the welding method according to paragraph 4.4.3.
5.1.3 Prototype test
Prototype test should be conducted during the development phase.
Fabricate test article to evaluate design and prove the validity of analysis result,and conduct the following tests as necessary.
a. Proof pressure testb. Leak testc. Pressure cycle test
d. Loading test for flight (only for launch vehicle propellant tanks)e. Burst pressure test (*1) or burst test (*1)
f. Negative pressure test (*2)
*1 Measure the strain when pressurized (except for components including
valves).
*2 Conduct this test only when internal pressure is expected to become
negative with respect to external pressure during the period fromfabrication to completion of the number of planned flights.
Judgment criteria for prototype tests are as follows:a. Proof pressure test
Follow (1) of paragraph 4.7.5.1.

133

b. Leak test
Follow (2) of paragraph 4.7.5.1.
c. Pressure cycle test
Follow (1) of paragraph 5.2.
d. Loading test for flight
The test article should not buckle or burst.
e. Burst pressure test (*1) or Burst test (*1)
Follow (2) of paragraph 5.2.
f. Negative pressure test (*2)
The test article should not buckle when negative pressure is applied to it.
5.2 Qualification Test
Qualification test which incorporate actual environmental conditions shall be
conducted during the last phase of high-pressure gas equipment development toverify the validity of the design, fabrication, and inspection processes.
Qualification tests may be omitted when qualified high-pressure gas equipment or
those with small alternation are used.
In qualification test, use test articles fabricated following the same fabrication andinspection processes as the flight model. After passing the inspection and the test
specified in paragraph 4.7, the test article shall undergo the f ollowing tests.
Test pressures for the proof pressure testing in paragraph 4.7.5.1(1) should in
principle be corrected for the difference between the measured minimum thicknessof the test specimen and the design minimum thickness, simulat ing the case where
the test piece is fabricated at the minimum design thickness.
(1) Pressure cycle testa. Conduct a pressure cycle test according to vessel construction.
For metallic pressure vessels, pressure cycle testing according to either of thefollowing:
1) Twice the number of cycles of the required life at the MEOP, applying
pressure 1.5 times of the MEOP.
2) Four times the number of cycles of the required life at the MEOP, applying
the MEOP.
Note: When multiple proof pressure tests are to be conducted during flightmodel operations, add the additional number of pressure cycles
required to the pressure cycles of either 1) or 2).

134

For COPV, Pressure cycle test according to either of the following:
1) Four times the number of the planned proof pressure tests at test pressure(if two or more tests are conducted for operation of the flight model, addpressurization required for proof pressure testing) and four times the numberof proof pressure tests required at MEOP.
2) Four times the number of the planned pressure cycles in the applicablesequence of pressurization and depressurization (applicable only when apeak operating pressure generates tensile stress that exceeds an initial
compressive stress value for metallic liners as given by autofrettage)
Note: The planned pressure cycle means a series of pressure cycles suchas the number of times required for proof pressure tests, airtight tests,
and MEOP applications.
b. After testing, perform external appearance inspections and confirm there areno harmful deformations, cracking, or other abnormalities.
c. The bellows as shown in Table3.1.3-1 No.5 is needed the pressure cycle test
as required to pressure vessel. Both pressure cycle and displacement cycle
shall be considered in the pressure cycle test.
d. The pressure cycle test may be omitted if the test is too difficult to conduct forlaunch vehicle propellant tanks.
(2) Burst pressure test
a. Burst pressure testing is in principle performed at the design burst pressure
and at a temperature corrected for the material strength, and at a pressure
corrected for the difference between the minimum measured plate thickness
and the design minimum plate thickness of the specimen. Ensure that the
specimen does not break at below the corrected pressure.
For COPV, the pressure retaining period is longer than 30s.
b. The burst test following above burst pressure test is recommended.
For the burst test, pressurize the test article beyond the design burst pressure
until the test article bursts and confirm the equipment's strength margin.
c. For the burst test of metallic pressure vessels, compare the actual burst
pressure with the predicted pressure calculated from the flow stress equations
as shown below.
Flow stress equations
1) Cylindrical shell
PB 

2  y  u  t


R
2
3 
 i

135

2) Spherical shell y  u  tPB  2
R
2

 i

PB :

Burst pressurey :Material yield stressu :Material tensile strength

Ri :Inner diameterｔ :Thickness

Notice: Actual values of the property of the burst tested metallic
pressure vessel are used in above equations.
(3) Vibration test
a. In the vibration test, conduct random vibration test, sinusoidal wave vibration
test, and acoustic test.
b. When the qualification test specified in (1) or (2) above could not cover thevibration requirement by the environment specified in paragraph 3.1.2.2,
conduct the vibration test.
c. Specify the test conditions including the vibration levels and loading time asvibration test requirements.
d. Launch vehicle propellant tank is not required to conduct vibration test.
(4) Ground handling load test
The launch vehicle propellant tank shall be loaded ground handling load asneeded (*1) and confirm validity of design analysis according to paragraph 3.5.1.3(the special factor shown in paragraph 3.1.2.3 and the safety factor shown inparagraph 3.1.3.4 are assured).
*1 In the case when ground handling load is the most severe load for the shell
thickness calculation.
(5) Operational cycle test and displacement cycle test
The high-pressure gas equipment having moving mechanism such as
electromagnetic valve, fill and drain valve and so on shall be qualified byoperational cycle test. The cycle number is set by the multiple of the cycle number
from paragraph 3.1.5 (3) and safety factor given from space system. For the
bellows the displacement cycle test shall be done instead of operational cycle
test. However, the bellows which is defined in table 3.1.3-1 No.5 shall be qualified
by the pressure cycle test according to paragraph 5.2.(1) c.
(6) Interlaminar shear testing136

Except for carbon fiber-reinforced epoxy composites, the resin-impregnated fiber
layer of the COPV must pass interlaminar shear testing using equivalent test
materials as follows:a. Perform testing on five test pieces in accordance with ASTM-D2344, JIS K
7078, or JIS K 7057.
b. If a test piece breaks as a result of testing in a form other than horizontal
interlaminar shear failure, invalidate the test results, collect a replacement
test piece, and repeat the test.
c. Perform testing at the design temperature.
d. The test is passed if the shear stress value for each test piece is 35 N/mm 2
or higher.

137

6. Reuse
When reusing reusable high-pressure gas equipment, define the degradation
factors during the mission, ground operations and storage. Ensure safety byanalyzing or testing for the degradation factors. Major degradation factors aremechanical factors such as pressure, vibration, acceleration, and shock;environmental factors such as cosmic radiation and heat; chemical factors such as
corrosion caused by propellant or pressurizing gas.
Figure 6-1 shows the task flow for reuse.
6.1 Reuse Inspection
6.1.1 Visual inspection
Confirm that no abnormities such as harmful flaws, deformations, dents or
corrosion exist.
6.1.2 Nondestructive inspection
Conduct the following nondestructive inspection as required ensuring that nodefects harmful to the high-pressure gas equipment exist. When visual inspection
reveals a defect or when a repair is performed, select and perform an appropriate
test method from among the following:(1) Penetrant testing
Perform penetrant testing on base metals and the surface of welded parts inadherence to the testing standards specified in AMS-2645, ASTM-E1417, or theequivalent. Judgment criteria are according to paragraphs 4.7.2 and 4.7.3. The
eddy current testing or ultrasonic inspection described in paragraphs 4.7.2(3) and4.7.3.5(1) may be performed in place of penetrant testing.
(2) Radiographic testing
Perform radiographic testing in adherence to ASTM-E1742 or an equivalent
standard on welded part interiors. Judgment criteria are as per paragraph 4.7.3.

(3) Ultrasonic testing
Perform ultrasonic inspection in adherence to ASTM-E164 or an equivalent
standard on welded part interiors. Judgment criteria are as per paragraph 4.7.3.
6.1.3 Dimension inspection
Perform dimension inspection of the high-pressure gas equipment for which
dimension change will affect strength during mission operation or for which
dimension is changed due to the repair specified in paragraph 6.3, and ensure thatthe dimension satisfy the drawing requirement.

138

6.2 Reuse Test
(1) Proof pressure test
For reuse test, conduct the proof pressure test to confirm structural integrity forthe following cases. Sufficiently examine whether the proof pressure test is
performed or not, because the proof pressure test could reduce the life of highpressure gas equipment.
a. When repaired
b. When reuse high-pressure gas equipment which is suspected to have been
stored for a long period under conditions not satisfying the requirements
specified in (2) to (4) of paragraph 8.
c. When the proof pressure test is considered to be necessary.
The proof pressure test, if conducted, shall comply with (1) of paragraph 4.7.5.1
and (1) of paragraph 4.7.5.2.2, “Proof pressure test.”(2) Leak test
Perform the leak test as specified in (2) of paragraph 4.7.5. 1 and (2) of paragraph4.7.5.2.2, “Leak test.”
6.3 Repair
When structural damage or a defect exceeding allowable level is found in reuseinspection, or when the equipment is rejected by reuse test, appropriately repair
the high-pressure gas equipment. If the repair is not feasible, re -fabricate andreplace such high-pressure gas equipment.
Repair so as to maintain the material characteristics and repair within thedimensional tolerance. When the repair deviates from the dimensional tolerance,
ensure that problem does not occur by conducting additional analysis or test.
Because the repair could reduce strength, determine the need to repair damage ordefects considering the result of flaw growth analysis described in paragraph3.5.4.1.
When high-pressure gas equipment is repaired, conduct the proof pressure test in
the reuse test. Determine to repair with enough consideration because it will affectthe number of pressurization cycle which are estimated by planned number offlights.
Repair which does not affect the strength (e.g., replacement of seals for leakage
found in the leak test) does not require the proof pressure test in the reuse test.

139

History Managment
Transportation

Judgment
ReturnYes

No
Reuse Inspection

Visual inspection

RepairRepairOperations

LaunchNon-destructive
Inspection

Judgment
Yes

No

Installation
Non-destructive
Inspection Required?
Transportation

Yes

Yes＊1
No

Judgment
Yes

Repairable?

No

No

Refabrication
orReplacement

Dimension
Dimension Inspection
Inspcetion
required?
Yes＊1
No
Judgment
Yes

No

Reuse Test
Proof
Pressure Test required?

Proof Pressure Test

Yes＊1

No
Leak Test＊2

Judgment
Yes

No*1 Nondestructive
inspection, dimension
inspections, and proof
pressure tests should
be conducted fore q u i p m e n t wh i c h h a s
been repaired.
*2 Ni-H2 batteries andheat pipes are sealed
and cannot bepressurized to the
ME O P . L e a k a g e m a y
be checked at theoperating pressure.

Judgment
Yes

No

Figure 6-1 Task Flow for Reusing Reusable High-Pressure Gas Equipment140

7. Safety Assurance During Pressurization
Observe the following rules to assure safety of testing personnel when pressurizing
the high-pressure gas equipment in the leak test, proof pressure test or pressure
gas loading at the launch site.
(1) Pressure relief valve or equivalent function (hereinafter referred to as safety
device) should be installed to the test equipment to prevent excessive
pressurization. In some case where safety device cannot be installed to the test
equipment, safety device may be installed to the ground support equipment.
Pressure settings for safety valves, etc., are as follows, with pressure
corresponding to the blow start pressure.
- For leak test: Airtightness test pressure＋ Positive test pressure tolerance- For filling: MEOP
When taking the blow pressure as the pressure setting, it should be less than
1.1 times the blow start pressure. The tolerance is according to JIS B 8210.
(2) Pressurizing/Depressurizing shall be operated remotely or operated manuallyfrom protected place.
(3) Facility shall be furnished to exhaust a pressurized fluid urgently.
(4) Pressurize after judging whether personnel can approach the high-pressure gas
equipment according to the requirements or not in Tables 3.1.3-1 and 3.1.3-2.
(5) If the COPV capacity is 500 L or less and tensile testing is performed on thebase material of liners (excluding nonmetal liners) or welded parts duringcertification testing, use the following pressures. For other high-pressure gas
equipment, when applying pressures more than 1/4 the design burst pressure,
perform pressurization and depressurization from beyond an appropriate
distance for safe operations or while using an appropriate protective barrier.
Carbon fiber composite pressure vessels: more than 1/2.25 of design burst
pressure
Aramid fiber composite pressure vessel: more than 1/3 of design burst
pressure
Glass fiber composite pressure vessel: more than 1/3.5 of design burst
pressure(6) When personnel must approach vessels at the pressures described in item (5),observe pressure changes after pressurization is completed, and confirm thatpressure has stabilized before approaching.

(7) When the pressure applied to the pressure vessel exceeds the MEOP, conduct
such pressurization in a pit or equivalent structure.

141

(8) Safety control personnel shall be present at the test.
Note: Although safety needs to be ensured for N i -H 2 batteries or heat pipes thatare pressurized or depressurized in normal operations, portions of items (1)to (3), (7) and (8) above may be omitted when it is considered to be
impracticable.

142

8. Handling(1) To confirm that high-pressure gas equipment can be operated normally, perform
historical management for the number of flight, the required life for pressure
cycle, operating cycle, displacement cycle, inspection result at acceptance andoperation, and repair record according to paragraph 3.1.5.
(2) Do not use fluids, gases, inspection solutions, or other auxiliary materials forhigh-pressure gas equipment fabrication and inspection if such materials will
corrode or embrittle the materials for high-pressure gas equipment or may leadto destruction, leakage, or contamination of the high-pressure gas equipment.
(3) Purge high-pressure gas equipment with low-pressure, clean, dry inert gas or
maintain dry air that has passed through desiccants before handling and storage
to prevent internal contamination due to dust, deformation due to creep or self weight, and corrosion.
(4) Store high-pressure gas equipment in temperature and humidity-controlled
rooms to prevent degradation during storage due to external environments.
High-pressure gas equipment should be stored in containers to protect it from
unnecessary external forces.
(5) During ground handling and transportation, avoid excessive loads on highpressure gas equipment by limiting handling methods, reinforcement with jigs,
and protection by containers.
(6) Comply with the damage prevention control plan according to 3.6.1.2.

143

9. Measures for Revisions
When these technical standards are revised, the revised version is effective
immediately after issuance, but conformance assessments based on these technicalstandards will be implemented as follows.
(1) Conformance assessments in the pre-revision edition are in principle limited to
six months following issuance of the revised edition.
(2) When applying for a fabrication conformity review according to a revised edition
for a device issued conformity certification by design conformity review under a prerevision edition, ensure that all revised items conform to the design conformity
review, and carry out special treatment if they do not. In such cases, conformity
certification based on the design conformity examination under the pre -revision
edition is valid for future devices having the same design.
(3) In the case of equipment for which conformity certification was issued by adesign conformity review under the pre-revision edition, if there are items among
the revised items not matching the design conformity review, and if special treatment
could not be completed, conformity certification by production conformity inspection
will be issued if the fabrication results all conform with the revised version.

144

APPENDIX
The symbols used in this technical standard are defined below. Please note thatthese definitions apply to the representative examples. If the symbols are used forthe definitions other than those specified below, the applicable definitions are
explained in appropriate paragraphs.
aFlaw size (flaw depth "a" or flaw length "c").

a cr

Critical flaw size (depth) that results in destruction or through thickness ofhigh-pressure gas equipment under the MEOP.

ai

Size (depth) of initial flaw guaranteed by the flaw detection pressure test.

D

Major axis of ellipsoid inside of head.

D0

Outer diameter of the large opening of a conical head.

doOuter diameter.

diInternal diameter.

E

Modulus of longitudinal elasticity.

F

Increment of stress to primary and secondary stresses due to stressconcentration generated by structural discontinuities, such as unevensurfaces or notches (peak stress) Includes incremental stress due toangular deformation and unevenness at weld joints.

h

One half of the minor axis of ellipsoid inside of head.

K

Stress intensity factor.

KC

Fracture toughness.

KR

Fracture resistance.

K

Fluctuation range of stress intensity factor, K.

Lr

Internal pressure: P divided by plastic collapse pressure: P c

ND

Number of loading cycles until thru-thickness penetration or unstablefracture of high-pressure gas equipment results.

Nf

Fatigue life.

Ni

Number of loading cycle.

niNumber of cycle in the stress range.

P

MEOP.

P0

Plastic collapse pressure.

PB

Burst pressure.

Pb

Stress intensity of bending stress.

Pc

Plastic collapse pressure at design temperature

PL

Stress intensity of local primary membrane stress.

145

Pm

Stress intensity of general primary membrane stress generated by the
MEOP.

P.F

Proof factor.

Q

Secondary stress.

R

Internal radius of the central part of a torispherica l head or total
hemispherical head.

R1

Stress ratio (R1=K MIN /K MA X ).

RiInternal radius of a cylinder.

Ro

Outer radius of a cylinder.

r1

Internal radius of the round corner of a torispherical head.

r2

Internal radius of the round part continuing to the larg e opening of aconical shell.

Sm

Design stress intensity.

S.F 1

Safety factor (S.F1=4).

t

Minimum thickness

tc

Thickness of composite material when artificial isotropy is assumed.

tm

Thickness of a metallic liner.

t

Helical winding layer.

thThickness of hoop winding.

uDistance toward plate width from internal surface (flaw side).

W

Coefficient relating to a torispherical shape.

zDistance of thickness direction from internal surface (flaw side).

fBreaking elongation (true strain of fracture).

 tTotal strain range.

One half of the apical angle of the cone.



Plastic constraint factor (deepest point = 1.68 and surface point = 1)

Poisson ratioStress.

bNominal (maximum) bending stress.

hMaximum value of hoop stress (circumferential stress).

iStress distribution with approximation of polynomial equations (i = 0 to 3).

mMean stress.

uTensile strength of material

yYield stress of material or 0.2% proof stress.

146



Virtual elastic stress range.

147