HPIS
Standard Test Method for Humid Gas Stress Corrosion Cracking of
Aluminium Alloys for Compressed Hydrogen Containers

HPIS E 103:2024

Revised：2024-XX-XX
Edited and Issued by High Pressure Institute of JapanAll rights reserved especially (also in extracts) for translation, reprinting, reproduction by copying or other technical means.

HPIS E 103:2024

List of Members of the Pressure Equipment Codes and Standards Council(Chairman)

Yoshio Takagi

Thermal and Nuclear Power Engineering Society(Vice Chairman)

Seiji Asada

Mitsubishi Heavy Industries, Ltd.

(Committee member) Kazuhiro Kimura

National Institute for Materials Science

Hisashi KatoThe High Pressure Gas Safety Institute of Japan

Takeshi Ogawa

Aoyama Gakuin University

Tomohisa Kumagai

Central Research Institute of Electric Power Industry

Tetsuya Sasaki

National Institute of Occupational Safety and Health,Japan(Secretariats)

Nobuhiro Yoshikawa

The University of Tokyo

Kengo Ishige

IHI Corporation

Haruki Igari

Nippon Steel & Sumitomo Metal Corporation

Shunsuke Sasaki

Toshiba Energy Systems & Solutions Corporation

Susumu Terada

Kobe Steel, Ltd.

Katsumasa Miyazaki

Hitachi, Ltd.

Yoichi Isizaki

Idemitsu Kosan Co.,Ltd.

Satoru Koyama

Sumitomo Chemical Co., Ltd.

Masaru Sekiguchi

Tokyo Gas Co., Ltd.

Noboru Kizuki

The Japan Gas Association

Yuichi Nakagawa

Mitsui Chemicals, Inc.

Yasuhiro Mitarai

Chiyoda Corporation

Shunji Kataoka

JGC CORPORATION

Takemitsu Satou

Japan Power Engineering and Inspection Corporation

Hiroyuki Doi

Toyo Engineering Corporation

Hiroyasu Matsuda

Best Materia Co.

Yukinori Mitani

IHI Inspection & Instrumentation Co., Ltd.

Noriaki Maruo

High Pressure Institute of Japan

Yukako Tanaka

High Pressure Institute of Japan

Instituted:2018-01-31
Revised:2024-XX-XX

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HPIS E 103:2024

Exclusion Clause of High Pressure Institute of Japan
This standard has been established by High Pressure Institute of Japan, through committee discussions
with persons of expert knowledge and special interest, and who are active in a wide range of fields, without
limiting to specific expertise, job type, or affiliation.
High Pressure Institute of Japan is responsible for the explanation of this standard, however, does notguarantee the results of activities and manufacturing performed according to this standard.
High Pressure Institute of Japan does not bear responsibility of compensation in case of infringement of
the intellectual properties of a third party which may occur as a result of the use of this standard. The user ofthis standard shall be wholly responsible for the use of this standard with the awareness that he/she will beheld responsible for any intellectual property infringement of a third party occurred as a result of activities
related to this standard.
Furthermore, although related government agencies and personnel in the industrial fields may haveparticipated in the discussion and establishment of this standard, this does not mean that the related
government agencies and industrial fields have given their approval for this standard.

Foreword
This standard was authorized by the board of directors of High Pressure Institute of Japan through draftingby the HG-SCC Committee, consideration by the Pressure Equipment Codes and Standards Council andpublic comment.
This second edition cancels and replaces the first edition (HPIS E 103:2018).

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Contents

Page

Introduction ..................................................................................................................................................... 1
1

Scope ....................................................................................................................................................... 1

2

Normative references .............................................................................................................................. 1

3

Terms and definitions .............................................................................................................................. 1

4

Principle .................................................................................................................................................. 2

5Specimens ............................................................................................................................................... 2

5.1

Specimen geometries........................................................................................................................... 2

5.2

Materials .............................................................................................................................................. 3

5.3

Specimen orientation ........................................................................................................................... 3

6

Fatigue pre-cracking ................................................................................................................................ 3

7

Test method ............................................................................................................................................. 4

7.1

Loading ............................................................................................................................................... 4

7.2

Test environment and period ............................................................................................................... 5

7.3

Measurement of force.......................................................................................................................... 5

7.4

Fatigue post-cracking and breaking .................................................................................................... 5

7.5

Measurement of crack length .............................................................................................................. 6

7.6

Validity of test ..................................................................................................................................... 6

8

Qualification of materials ........................................................................................................................ 7

Annex A (normative) The compact specimen ................................................................................................. 9Annex B (normative) The single-edge-notched bend specimen (SE specimen) ........................................... 12
Bibliography.................................................................................................................................................. 14
Explanation ...................................................................................................................................................E1
List of Members of the HG-SCC Committee ................................................................................................E2(1)
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Standard Test Method for Humid Gas Stress Corrosion Cracking of
Aluminium Alloys for Compressed Hydrogen Containers
Introduction
This standard is established at the request of automotive industry in order to evaluate the humid gas
stress corrosion cracking (HG-SCC) susceptibility of aluminium alloys used in compressed hydrogencontainers.

1 ScopeThis standard specifies the test method for humid gas stress corrosion cracking (HG-SCC) and thequalification criteria of aluminium alloys for compressed hydrogen containers for automotive use.

2

Normative references
The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6892-1, Metallic materials – Tensile testing – Part1: Method of test at room temperature
ISO 7539-6:2018, Corrosion of metals and alloys – Part 6: Preparation and use of precracked
specimens for tests under constant load or constant displacement
ISO 7866:2012, Gas cylinders – Refillable seamless aluminium alloy gas cylinders – Design,
construction and testing
ASTM E399-23, Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness of Metallic
Materials

3

Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 7539-6:2018 and thefollowing apply.
HG-SCC (Humid Gas Stress Corrosion Cracking)stress corrosion cracking in a humid gas environmentKIstress intensity factor of a crack subjected to opening mode displacements (mode I)

1
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KIAPP
stress intensity factor of a crack when a force was applied to the specimen at the beginning of the HGSCC test
σ0.2
average of the 0.2% proof stress of two specimens measured at room temperature in accordance withthe procedures given in ISO 6892-1
small scale yielding condition
condition in which the plastic zone at the crack tip is so small in comparison to the dimensions of thespecimen that the plastic zone does not significantly affect the stress distribution in the surrounding
elastic zone, thus enabling the description of the field of stress at the crack tip in terms of stress intensity
factor K
plane strain condition
condition in which the dimensions of the plastic zone at the crack tip are so small in comparison to
the length of the crack and to the thickness of the specimen that plastic deformation along the thickness
direction inside the plastic zone is restricted by elastic deformation in the surrounding elastic zone (dueto difference in the Poisson’s ratios), thus generating a tensile stress in the thickness direction andattaining a tri-axial tensile stress state4

Principle

A fatigue pre-cracked specimen is loaded by a constant-force or constant-displacement method to a
KIAPP equal to a defined value. Then, the specimen is maintained in the loaded state at prescribed
environment for a prescribed duration. After the test duration, the specimen is examined as to whether
or not the cracking has extended from the initial fatigue pre-crack. If the crack extension length does
not exceed a prescribed value, the material of the specimen is considered suitable for compressedhydrogen containers as far as the required resistance to crack extension under loading is concerned.

5

Specimens

5.1

Specimen geometries

The geometries of the HG-SCC specimen shall be as follows.
a)

One of the specimen geometries, or a combination of them, shall be used for the tests.
1)Compact specimen shown in A.1.

2)

Single-edge-notched bend specimen (SE specimen) shown in B.1.

3)

Double-cantilever-beam specimen (DCB specimen) shown in Figure 4 of ISO 7539-6:2018.

4)

Modified wedge-opening-loaded specimen (modified WOL specimen) shown in Figure 5 ofISO 7539-6:2018.
2

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5)b)C-shaped specimen shown in Figure 6 of ISO 7539-6:2018.

Net width W, thickness B and half-height H shall be measured within an accuracy of 0.1% of W
along a line existing within 10 % of W from the crack plane.

c)

The faces of the specimen shall be processed so as to make the crack detectable and its length
measurable.

5.2

Materials

Specimens are of wrought aluminium alloy products (plate, extruded and forged products).

5.3

Specimen orientation

The orientation of specimen sampling shall be as follows.
a)

HG-SCC test specimens: Y-X orientation. Other orientations may be added when necessary.

b)Tensile test specimens: Y orientation.
NOTE

6

The orientation of specimen is defined in Figure 15 of ISO 7539-6:2018.

Fatigue pre-cracking
A fatigue pre-crack shall be introduced as follows (in accordance with Clause 6 of ISO 7539-6:2018).

a)

A fatigue pre-crack is introduced at room temperature in the atmosphere according to the following
procedures.
1)

Force control accuracy of the fatigue testing machine is within ± 2.5 % of the force applied.

2)

The crack is measured on both surfaces of the specimen.

3)

The crack is extended by 2.5 % of W or by 1.25 mm whichever is larger, on both surfaces.

4)

The stress ratio R is from 0 to 0.1.

5)

The crack may be started at KI values higher than the expected KIAPP ; but, during the final 0.5
mm of crack extension, the fatigue pre-cracking shall be completed at a maximum stressintensity factor as low as possible (less than 60 % of KIAPP).

6)

To facilitate the introduction of a crack, the geometries of the notch tip are prescribed as shownin Figure 16 of ISO 7539-6:2018.

7)

At the initiation or during extension, the crack shall not deviate an angle exceeding 10° fromthe plane of the notch, and the difference between the crack lengths on both surfaces of thespecimen shall not exceed 5 % of W.
NOTE

See FIG. 3 of bibliography [2] for the crack deviation angle from the plane ofnotch.

b)

Effective crack length a including the fatigue pre-crack shall fulfill the following equation for small
scale yielding as specified in B.5 of ISO 7866:2012.
2

𝐾

𝑎, (𝑊－𝑎) ≥ 1 270 ( 𝜎IAPP )0.2................................................................................ (1)where
3
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a: effective crack length (mm)W

: specimen actual net width (mm)

KIAPP : stress intensity factor of a crack when a force was applied to the specimen (MPa√m)
σ0.2 : 0.2 % proof stress (MPa)7

Test method

7.1

Loading

The loading test shall be conducted according to the following method.
a)A force is applied under constant-force or constant-displacement conditions.

b) Loading accuracy is attained as follows.
1)

For constant-force condition, it is necessary to employ a testing machine capable of force
accuracy control within ±1 % of the force applied, as defined in 7.6.3 of ISO 7539-6:2018.

2)

For constant-displacement condition, the sensitivity of the displacement gauge shall be not lessthan 20 mV/mm so as to minimize the excess amplification of small signals. The linearity of thegauge is such that the deviations from the true displacements shall not exceed 3 μm (0.003 mm)
for smaller displacements up to 0.5 mm and not exceed 1 % of recorded values for larger
displacements. These conditions are in accordance with 7.5.3 of ISO 7539-6:2018.

c)

The value of KIAPP obtained by the following equation given in B.6.2 of ISO 7866:2018 is loaded.
𝐾IAPP = 0.056𝜎0.2......................................................................................... (2)Additionally, the effective crack length a used in the calculations for the following d) or e) is theaverage value of the crack lengths measured on both surfaces of the specimen [see a)7) of Clause 6].
NOTE

Because a fatigue pre-crack, in many cases, does not propagate symmetrically on the
middle thickness plane of the specimen, a (the average value of the crack length measured
on both surfaces of the specimen) is different from apre measured on the fracture surface(see 7.5). Therefore, it is recommended to perform additional testings where KIAPP is
greater and/or smaller (e.g. 5 % for each) than that of equation (2) at the same time [seec) of Clause 8].

d)e)

For constant-force method, the force (P) shall be defined as follows:1)

Compact specimen: use the equation shown in A.2.

2)

SE specimen: use the equation shown in B.2.

3)

DCB specimen: use the equation shown in B.6.5 of ISO 7866:2012.

4)

Modified WOL specimen: use the equation in Figure 11 of ISO 7539-6:2018.

5)

C-shaped specimen: use the equation in Figure 14 of ISO 7539-6:2018.

For constant-displacement method, the force shall be applied as follows:1)

Compact specimen: use the equation shown in A.3.
4

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2)

SE specimen: use the equation shown in B.3.

3)

DCB specimen: use the equation in Figure 10 of ISO 7539-6:2018.

4)

Modified WOL specimen: use the equation in Figure 11 of ISO 7539-6:2018.

5)

C-shaped specimen: use the equation shown in B.6.4 b) of ISO 7866:2012.

7.2

Test environment and period

The loaded specimens shall be tested under the following conditions.
a)Temperature: 25 °C ± 5 °C for the entire duration of the test.

b)

Atmosphere and humidity: no generation of dew in air measuring 85 % or higher in relative
humidity for the entire duration of the test.

c)

Test period: 90 days (in accordance with B.6.6 of ISO 7866:2012)
NOTE Typically, the specimens are set in the chamber and the sensors to measure temperature andrelative humidity are located near the specimens to maintain the conditions a) and b).

7.3

Measurement of force

7.3.1 For constant-displacement condition, the force shall be measured by the following method
after the 90-day test period.
a)When the force is not monitored:
1)

At the end of the test, the crack mouth opening displacement is measured before removal of theforce.

2)

The force is removed.

3)

The force is reapplied until the crack mouth opening displacement attains the value in 1) witha force measuring instrument.

b)When the force is monitored, the force at the end of the test is measured. It is also acceptable tocalculate the force value from the values of elastic strain measured between the start and the endof the test.

7.3.2 If the force measured as 7.3.1 is less than 95 % of applied force P, the test specimen should be
rejected without waiting for the final qualification of materials (see Clause 8).
NOTE It has been confirmed that the crack length extension by HG-SCC exceeds 0.16 mm [thethreshold length defined in a) of Clause 8] when the measured force decreases to less than
95 % of applied force P.

7.4

Fatigue post-cracking and breaking

7.4.1 Fatigue post-cracking shall be introduced as follows.
a)

For constant-force condition, a fatigue post-crack is introduced until the post-crack length isextended to 1 mm or more by fatigue loading with a force not exceeding 0.6 times the value
obtained by 7.1 c) and 7.1 d).

b)

For constant-displacement condition, after the force measurement as 7.3.1 the loading is removed
5
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and a fatigue post-crack is introduced until the post-crack length is extended to 1 mm or more by
fatigue loading with a force not exceeding 0.6 times the value obtained by 7.3.1.
7.4.2 After the introduction of a fatigue post-crack, the specimen shall be broken open.
7.4.3

If it is possible to identify the HG-SCC fracture surface, the specimen may be broken by amethod other than the introduction of a fatigue post-crack.

7.5

Measurement of crack length

After breaking of the specimen, the following aspects of crack length shall be measured using ascanning electron microscope (SEM) or other measuring instruments with an accuracy within ±0.01 mm.
a)effective crack length including the fatigue pre-crack

apre

b)

effective crack length up to the tip of the HG-SCC crackascc

The measurement shall be conducted from the direction perpendicular to the broken surface at thepositions 25 %, 50 % and 75 % of the specimen thickness, and the average value of the measurements
at these 3 points is selected as the effective crack length.

7.6
Validity of test
7.6.1 Fatigue pre-crack
Of the apre values for the positions 25 %, 50 % and 75 % of the specimen thickness, it shall be verified
that the difference between the largest and smallest values does not exceed 5 % of net specimen widthW.

7.6.2 Small scale yielding and plane strain conditions
It shall be verified that a, (W - a) and B satisfy the following equation as specified in B.6.7 of ISO
7866:2012.
𝐾

2

𝑎, (𝑊 − 𝑎), 𝐵 ≥ 1 270 (𝜎 I )....................................................................(3)0.2Where，a, (W - a) and KI are as follows.
― For constant-force condition:
・

In case of(ascc – apre) ≤ 0.16 (mm)𝑎 = 𝑎scc(𝑊 − 𝑎) = (𝑊 − 𝑎scc )𝐾I = 𝐾IAPP

・(provided that a = ascc)

In case of (ascc – apre) > 0.16 (mm)𝑎 = 𝑎pre + 0.16
(𝑊 − 𝑎) = {𝑊 − (𝑎pre + 0.16)}
𝐾I = 𝐾IAPP(provided that a = apre + 0.16)

6
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― For constant-displacement condition:𝑎 = 𝑎pre(𝑊 − 𝑎) = (𝑊 − 𝑎pre )𝐾I = 𝐾IAPP
The units used in the above equations are same as the units used in Equation (1).
If test conditions do not satisfy these requirements, the test is invalid and shall not be used in thequalification of materials specified in Clause 8.

8

Qualification of materials
The applicability of materials shall be judged as follows.

a)

The crack extension (ascc - apre) by HG-SCC [see 7.5 a) and 7.5 b)] is examined to exceed 0.16 mm
or not.
NOTE The threshold value of “0.16 mm” is specified in B.7.3 of ISO 7866:2012.

b)

The actual applied value of KIAPP, which is defined as KIA, is calculated by using apre and the force
applied according to 7.1 for constant-force condition and 7.3 for constant-displacement condition.

c)

The validity of materials is judged as shown in Table 1.

7
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Table 1 Qualification of materials
Case

Crack extension

KIA versus KIAPP

Judgment aⅠ(ascc – apre) ≤ 0.16 mm

KIA < KIAPP

invalid

KIA ≥ KIAPP

pass

KIA ≤ KIAPP

fail

KIA > KIAPP

invalidⅡⅢ(ascc – apre) > 0.16 mm

ⅣaMaterial shall be judged as follows.
pass： Materials that satisfy this requirement are judged to have applicable
resistance to HG-SCC for compressed hydrogen containers as specified in
B.7.3 of ISO 7866:2012.

fail：Materials are judged to be failed for application for compressed hydrogencontainers.

invalid : Materials cannot be judged in these conditions.
In case Ⅰ, another testing is recommended in the condition KIA equals to
KIAPP or is in some degree greater than KIAPP.
In case Ⅳ, where KIA is considerably greater than KIAPP, another testing is
recommended because materials may pass in the condition KIA is a little
greater than KIAPP.

8
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Annex A(normative)
The compact specimen
A.1 Specimen geometries
Geometry of compact specimen is given in Figure A.1, and a detail of knife edge is shown in Figure
A.2.
NOTES
1 Compact specimens usually have a net width ranging from 25 mm to 50 mm.
2 Figure A.1 is in accordance with Figure 3 of ISO 7539-6:2018. However, the thickness B differsfrom that of Figure 3 of ISO 7539-6:2018.
3 Figure A.2 is in accordance with Figure 8 a) of ISO 7539-6:2018.

C
a

H1%

F  0.5 %N60

F  0.5 %

H1%

l

W

B

W : net width
C : total width= 1.25W

B : thickness=

H : half-height= 0.6W

D : hole diameter= 0.25W

𝑊
20

𝑊

to 2

F : half-distance between outer edges= 1.6D9
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N : notch width= 0.065W maximum

R : notch radius= 0.1 mm maximum recommendedl: effective notch length = 0.25W to 0.40W

a : effective crack length = 0.45W to 0.55W

N

V0

N/ 2

l

Figure A.1－Proportional dimensions for compact specimen

V0：knife edge spacing
Figure A.2－Knife edge for location of displacement gauges

A.2

Constant-force testing

For loading under constant-force conditions, force P shall be determined by the following equations
specified in Figure 13 of ISO 7539-6:2018 [see 7.1d)].
31.62𝐾IAPP 𝐵√𝑊･･････････････････････････････････････････ (A. 1)
𝑌(2 + 𝑥)(0.886 + 4.64𝑥 − 13.32𝑥 2 + 14.72𝑥 3 − 5.6𝑥 4 )𝑌=(1 − 𝑥)3/2
𝑃=

𝑥=

𝑎
𝑊

Where
P

: force (N)KIAPP : stress intensity factor of the tip of the crack (MPa√m)B: thickness (mm)W

: net width (mm)a: effective crack length (mm)10

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A.3

Constant-displacement testing

For loading under constant-displacement conditions, crack mouth opening displacement V shall be
determined by the following equations given in B.6.4 a) of ISO 7866:2012 [see 7.1e)].

𝑉=

𝐾IAPP √𝑊
0.032𝐸𝑓(𝑥)𝑓(𝑥) =
𝑥=･････････････････････････････････････････････ (A. 2)

2.24(1.72 – 0.9𝑥 + 𝑥 2 )(√1 − 𝑥)9.85 – 0.17𝑥 + 11𝑥 2𝑎𝑊

𝑉 = 𝑉𝑓 − 𝑉0
WhereV

: crack mouth opening displacement (mm)Vf

: knife edge spacing under loading (mm)V0

: knife edge spacing under no loading (mm)

KIAPP : stress intensity factor of the tip of the crack (MPa√m)
W: net width (mm)a: effective crack length (mm)E

: longitudinal elastic modulus (MPa)11
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Annex B(normative)
The single-edge-notched bend specimen (SE specimen)
B.1 Specimen geometries
Geometry of SE specimen is given in Figure B.1.
NOTE Figure B.1 is in accordance with FIG.A.3.1 of ASTM E399-23. However, the thickness B

l

a

W

differs from that of FIG.A.3.1 of ASTM E399-23.

2.1W (min.)

2.1W (min.)B

W : net width
B : thicknessl𝑊𝑊= 20 to 2: effective notch length = 0.25W to 0.40W

a : effective crack length = 0.45W to 0.55W
The faces of the specimen shall be processed as shown in 5.1c).
The geometry of the knife edge shall be in accordance with Figure A.2.
Notch radius should be 0.1 mm maximum.
Other conditions shall be in accordance with NOTES in FIG. A3.1 of ASTM E399-23.
Figure B.1－Proportional dimensions for SE specimen

B.2

Constant-force testing

For loading under constant-force conditions, force P shall be determined by the following equations
specified in A3.5.3 of ASTM E399-23 [see 7.1d)].
A loading fixture of SE specimen is given in A2.1 of ASTM E399-23.

𝑃 = 31.62𝐾IAPP

𝐵𝑊 3/2𝑆𝑓(𝑥)･･･････････････････････････････････････････ (B. 1)
12

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𝑓(𝑥) = 3√𝑥𝑥=1.99 − 𝑥(1 − 𝑥)(2.15 − 3.93𝑥 + 2.7𝑥 2 )2(1 + 2𝑥)(1 − 𝑥)3/2

𝑎
𝑊

Where
P

: force (N)KIAPP : stress intensity factor of the tip of the crack (MPa√m)B: thickness (mm)B.3

W

: net width (mm)a: effective crack length (mm)S：span of roller pins defined in A2.1 of ASTM E399-23 (mm)Constant-displacement testing

For loading under constant-displacement conditions, crack mouth opening displacement V shall be
determined by the following equations which are combined the equation (B.1) and the equation (A3.3)
specified in ASTM E399-23 [see 7.1e)].
A loading fixture of SE specimen is given in A2.1 of ASTM E399-23.

𝑉 = 31.62𝐾IAPP
𝑓(𝑥) = 3√𝑥√𝑊𝑞(𝑥) ････････････････････････････････････ (B. 2)
𝐸𝑓(𝑥)1.99 − 𝑥(1 − 𝑥)(2.15 − 3.93𝑥 + 2.7𝑥 2 )2(1 + 2𝑥)(1 − 𝑥)3/2

𝑞(𝑥) = 6𝑥[0.76 − 2.28𝑥 + 3.87𝑥 2 − 2.04𝑥 3 +0.66](1 − 𝑥)2𝑎

𝑥=𝑊
V = Vf －V0
WhereV: crack mouth opening displacement (mm)Vf

: knife edge spacing under loading (mm)V0

: knife edge spacing under no loading (mm)

KIAPP : stress intensity factor of the tip of the crack (MPa√m)
W: net width (mm)a: effective crack length (mm)E

: longitudinal elastic modulus (MPa)13
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Bibliography[1]

ISO 7539-1:2012, Corrosion of metals and alloys – Part 1: General guidance on testing procedures[2]

ASTM E647-13a, Standard Test Method for Measurement of Fatigue Crack Growth Rates[3]

ASTM E1681-03, Standard Test Method for Determining Threshold Stress Intensity Factor for
Environment-Assisted Cracking of Metallic Materials[4]

ASTM E1820-13, Standard Test Method for Measurement of Fracture Toughness

14
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Standard Test Method for Humid Gas Stress Corrosion Cracking of
Aluminium Alloys for Compressed Hydrogen Containers
Explanation
This explanation relates to the matters specified and/or described in HPIS E 103 and the relevant
matters, but does not constitute part of this standard.

1

Purpose of establishment
ISO 7866:2012 has been established as a standard for compressed hydrogen cylinders usingaluminum alloys (see Clause 2 of HPIS E 103), and its Annex B specifies "Test method to determine
the sustained-load cracking resistance of aluminium alloy gas cylinders". It is known that depending on
the type of alloy or temper of aluminum alloys, stress corrosion cracking (SCC) occurs when exposed
to a moist environment under loaded force. Since Annex B does not specify environmental conditions,
it is considered inappropriate to judge the suitability for cylinders based solely on the standard.
Therefore, the High Pressure Institute of Japan established HPIS E 103:2018 (first edition), which
specifies test methods and judgment conditions in a humid environment, based on ISO 7866. This
standard is intended to be applied not only to containers, but also to the evaluation of materials before
they are processed into containers.

2

Contents of the amendment
HPIS E 103:2024 (second edition) has the following amendments.

a)

In “2 Normative references”, the latest editions of ISO 7539-6 and ASTM E399 are cited. It has
been confirmed that the provisions cited by HPIS E 103 from these standards have not changed
from the old editions.

b)

The provision of a)7) of Clause 6 is revised from recommendation (should) to requirement (shall),because Clause 6 as a whole is a requirement.

c)In b) of Clause 6, a (effective crack length) was defined as “distance between fatigue pre-crack tip
and load axis in mm” in the first edition, which was intended for compact type specimens. Since
this standard applies to specimens of various type [see a) of 5.1], this definition statement has been
deleted.

d)

Regarding "― For constant force condition" in "7.6.2 Small scale yielding and plane strain
conditions", the first edition stated that the test was invalid if the small scale yielding and planestrain conditions were no longer met at the end of the test. In this second edition, the provisions are
divided into (1) “In case of (ascc – apre) ≤ 0.16 (mm)” and (2) “In case of (ascc – apre) > 0.16 (mm)”(0.16 mm is the value at which HG-SCC extension is judged to pass). This is because the test is
judged to be valid if the small scale yielding and plane strain conditions are met at the length of
HG-SCC extension in (1) and 0.16 mm of HG-SCC extension in (2).

e) In accordance with ISO and ASTM standards, a distinction has been made between force and load
throughout this standard. Also, the related expressions are revised.

E1
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List of Members of the HG-SCC Committee(Chairman)

Takeshi Ogawa(Committee member) Hideo Kobayashi

Aoyama Gakuin University
Tokyo Institute of Technology

Nobuhiro Yoshikawa The University of Tokyo(Secretariats)

Kenji Sakai

Toyo Engineering Corporation

Shigeki Sakakura

IHI Corporation

Shigenori Asami

Japan Light Metal Welding Association’s ex-vice-president

Hiroaki Tamura

Japan Automobile Research Institute

Yukako Tanaka

High Pressure Institute of JapanE2
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* For comments or questions regarding this standard, please contact High
Pressure Institute of Japan.
* Regarding orders for HPIS, HPI TR standard forms, please apply to High
Pressure Institute of Japan by document, such as FAX or email.
* In the event a correction to HPIS, HPI TR standard forms is issued, please
use the form in duplicate, since it will be inserted in High Pressure Instituteof Japan website (http://www.hpij.org/).

HPIS E103:2018
Standard Test Method for Humid Gas Stress Corrosion Cracking of
Aluminium Alloys for Compressed Hydrogen Containers
Revised 2024-XX-XX
Edited and Issued by High Pressure Institute of Japan
4-7-1, Nihonbashihoncho, Chuo-ku, Tokyo 103-0023, Japan
TEL +81-3-3516-2270
FAX +81-3-3516-2271
E-MAIL：hpi@hpij.org
http://www.hpij.org/

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