Technical Papers

Lining Tank（Basics）

1. Introduction
Fluororesin has excellent non-viscosity, chemical
resistance, slip characteristics, electrical characteristics,
and antistaining properties, and so is widely used invarious fields.

When selecting the optimal lining material, we should
consider corrosion resistance, antistaining properties,
washability, formability, and cost.
Table1‌Characteristicsof fluororesin, vinyl chloride, andglass linings
Fluororesin

Vinyl chloride

Glass

and is now expanding into Taiwan（1997）, China（2017）,(negative-pressure side)

Balance type

Fluid

Inactive against
most chemicals

VALQUA started manufacturing and selling fluororesin

and the U.S.（2017）. We have accumulated a wealth oflining technology, and would like to introduce ourtechnologies to customers not only in Japan but also
overseas. Therefore, we are publishing these three

Main market
Cost

ー

FV

ー

Applicable to any
chemicals except
alkaline chemicals

Semiconductor Water and sewage Pharmaceuticals
ChemicalChemicalModerate

Reasonable

Expensiveー

Shock‐resistantmaterials are available.
Alkali-proof materials
are available.
Heat‐resistantmaterials are available.

feature articles: the basics, applications, and future
directions.

2. Types of lining materials
There is a wide range of commercially-available lining

OthersーChemicals

The maximum service temperature of fluororesin andbalance types shown in Table1 are explained later.

materials including rubber, phenol resin, polyethylene,
epoxy resin, vinyl chloride, glass, and FRP. For
comparison with fluororesin, this article focuses onvinyl chloride, glass, and fluororesin. Table1 outlines

3. ‌Types and characteristicsof fluororesin linings

the characteristics of these three materials.

Five types of fluororesin are currently used for linings

Regarding the scope of application in terms ofas shown in Table2. However, PTFE （polytetra-

temperature and pressure, glass linings have thefluoroethylene）, PFA（tetrafluoroethylene-perfluoroalkyl

widest, and vinyl chloride linings have the narrowest.

vinyl ether copolymer）, and ETFE （ethylene

Generally, glass linings are used at high temperatures

tetrafluoroethylene copolymer）account for the majority

above 120ºC, which is the heatproof temperature of

thanks to their characteristics, which are summarized asadhesives. Glass linings also tend to be used forfollows:

negative-pressure areas. Although glass linings have

① Excellent chemical resistanceweaknesses such as fragility and vulnerability to② Outstanding heat resistancetemperature impacts, manufacturers market materials③ Non-viscositythat address such problems.

④ Excellent electrical characteristics
16

Summer 2018

lining tanks in Japan in 1972, more than 45 years ago,

Allowable
230℃
temperature 120℃（150℃） 60 ～ 70℃
Allowable pressure Depends on strength Depends on strength Depends on strength（positive-pressure side） of can bodyof can bodyof can body

No.35

Lining Tank（Basics）⑤ Low-friction characteristics

strongest types of chemical bond. In PTFE, F atoms⑥ Incombustibility

densely surround the C-C bonds, creating a structure⑦ Strong weather resistancethat is resistant to attacks on the C-C bond. Therefore,⑧ Purity

fluororesin has chemical resistance and low

Fluororesin is an excellent material because it has notpermeability.

just one, but all, of the above characteristics, and so is

In addition, due to weak intermolecular attractive force

used in many fields. These characteristics stem frombetween dissimilar atoms, fluororesin has non-viscous

fluororesin’s molecular structure. As shown in Figure1,

and antistaining properties. In addition, fluororesin has

PTFE consists of carbon（C）and fluorine（F）atoms.

low-friction characteristics thanks to the following

The two atoms form C-F bonds, which are one of theproperties: 1）The atomic arrangement of fluororesin isCharacteristics of fluororesins used for lining purpose

Unit

ASTM test method−（ＣＦ2−ＣＦ2）− nPFA−（ＣＦ2−ＣＦ2）− m−（ＣＦ2−ＣＦ）− n

FEP
ETFE
−（ＣＦ2−ＣＦ2）− m
（Ｃ
Ｆ
−
−m
2−ＣＦ2）−（ＣＦ2−ＣＦ）− n−（ＣＨ2―ＣＨ2）− n

PVDF−（ＣＦ2―ＣＨ2）−ｎ

CF3

℃

−

327

310

260

270

156−170

Specific gravity

−

D792

2.14−2.20

2.12−2.17

2.12−2.17

1.70

1.75−1.78

Tensile strength

MPa

D638

27.4−34.3

24.5−34.3

21.6−31.4

45.1

34.3−43.1

Extension％

D638

200−400300

250−330

100−400

80−300Compressive strength

MPa

D695

11.8

16.7

15.2

49

66.6−96

Impact strength（Izod）
Hardness（Rockwell hardness）
Hardness（Shore hardness）
Bend elastic constant

J/m

D256A

160

−

D785

−

−

−

R50

R77−83−

D2240

D50−55

D60

D55

D75

D75−77

MPa

D790

550

660−690

650

1400

2000−2480

Tensile elasticity

MPa

D638

400−550

−

340

820

1310−1500

Dynamic friction coefficient−

0.69MPa
3m/min

0.10

0.2

0.3

0.4

0.39

Thermal conductivity

W/(m･K)

C177

0.25

0.25

0.25

0.24

0.10 〜 0.13

Specific heat
Coefficient of linear
expansion
Ball pressure temperatureJ/(g･K)

−

1.0

1.0

1.2

1.9−2.0

1.4

10−5/℃

D696

10

12

8.3−10.5

5.9

7−14

℃

−

180

230

170

185

−

55

50

50

74

87−115
149｛

Heat
distortion
temperature

Thermal characteristics

Melting point160−374℃

0.45MPa

℃

121

74

72

104

Maximum service temperature℃（No load)）

260

260

200

150−180150

Ω−cm

D257（50％

＞1018

＞1018

＞1018

＞1016

2×1014kV/mm
Dielectric breakdown
strength（Short time）（Thickness of 3.2 mm）

D149

19

20

20−24

16

10

60Hz

−

D150

＜2.1

＜2.1

2.1

2.6

8.4

−

D150

＜2.1

＜2.1

2.1

2.6

8.4

1 0 6H z

−

D150

＜2.1

＜2.1

2.1

2.6

6.43
0.049

Inductivity｛｛

RH.23℃）

1 0 3H z

Dissipation
factorElectrical characteristics

17

Non-destructive Non-destructive Non-destructive

1.81MPa

Volume resistivity

Durability and other characteristics

Summer 2018
No.35

Mechanical characteristics

Physicalcharacteristics

ＯＲf△：applicable ◯：good◎：excellent ◉：outstanding－

Structural formula

PTFE

－

Characteristics

Table 2

60Hz

−

D150

＜0.0002＜0.0002＜0.00020.0006

1 0 3H z−

D150＜0.0002＜0.0002＜0.00020.00080.018

1 0 6H z−

D150＜0.00020.0003＜0.0005

0.005＜0.015

Arc resistance

s

D495

＞300

＞300

＞300

75

50−70

24h water absorption rate
Flammability Thicknessof 3.2mm
Limiting oxygen index

％

D570

＜0.01

＜0.03

＜0.01

0.029

0.04−0.06−（UL−94）

V−0

V−0

V−0

V−0

V−0

−

D2863

＞95

＞95

＞95

30

44

Effects of direct sunlight

−

−

None

None

None

None

None

Acid

◉

◉

◉

◎

○

Alkaline

◉

◉

◉

◎

○

Solvent

◉

◉

◉

◎

△

Technical Papers

an inflexible, dense, straight-chain structure. 2）The

temperature above their melting points to create asurface of fluororesin is smooth. 3）Fluororesin forms a

resin film on the liquid contact surface. Therefore,

unique crystal structure in which external forces tend tothere are no pinholes on the resin surface. This reporteasily cause sliding within a crystal or between crystals.

considers only corrosion-resistance coatings. There are

In addition, the molecules are arranged symmetrically,

limitations on increasing the film thickness of a

resulting in nonpolarity. Therefore, fluororesin has

coating. Under the same conditions, coatings are

exceptionally low dielectric constant and strong

inferior to fluororesin lining and Roto lining

insulation resistance.

（rotational molding）in terms of longevity.
To increase the film thickness of coatings, spraying
and baking processes are repeated several times.
However, the membrane sprayed first can be easily
peeled when subjected to cycles of repeated heating.
Therefore, the limit of coating application isconsidered to be approximately three times.
In Roto lining（rotational molding）, after can bodies
are defatted and baked, a given amount（calculated

Figure1

Molecular structure of PTFE

based on the film thickness and surface area）of resinis poured into the inner-diameter space of the canbody, which becomes the product. After pouring thewhich is a shortcoming of PTFE. Although PFA has

resin, the can body is rotated on a two-axis liningsome differences under extreme conditions, it can bemachine and heated at a temperature above its

categorized as a fluororesin similar to PTFE.

melting point from the outside. Through rotation in
the melting condition, the resin covers the inside

4. Differences‌
among fluororesin
sheet lining, coating, and Roto
lining（rotational molding）

surface of the can body. The can body is rotated and

Lining, as the name suggests, is a construction method

be only applied to PFA, FEP, and ETFE, which arewhich lines the inside of vessels and pipings, both ofmelting-type resins.

which are prepared separately in advance.

It is suitable for manufacturing complex shapes

Fluororesin sheet lining, coating, and Roto lining

including vapor pipes. Also, the film thickness can be（rotational molding） differ depending on theadjusted.

heated thoroughly until a uniform resin film forms.
Then, the can body is cooled while it is rotated.
Among fluororesins, this manufacturing method canmanufacturing method; Table3 shows the differences.
Regarding fluororesin sheet linings, the details are

As mentioned above, regarding coatings and Roto

explained later.

linings, resin is cooled while adhered to the metal

Coatings can be categorized into two major types

surface of the can body. As a result, the resin cannot

depending on the baking temperature. When coatings

thoroughly contact, causing distortion （residual

are used for non-viscous purposes （such as rice

stress） within the resin. This distortion causes

cookers and frying pans）, the baking temperature istroubles under severe specified conditions.

not raised to the melting point, and so pinholes form

In addition, the resin film used for coating and Rotoon the resin surface.

lining has a lower resin density than that in sheet

When coatings are used for corrosion-resistancelining, to which independently formed sheets are

purposes, the coating materials are baked at aapplied. This low density reduces the product lifespan.
18

Summer 2018

PFA is a thermofusion resin with improved workability,

No.35

Lining Tank（Basics）

Table3 Characteristics of Roto lining, coating, and sheet lining
Roto lining
Coating（rotational molding）
A can body is set
Manufacturing
Spraying → drying
on a two-axis lining
method→ baking → coolingmachine.
Metal selection
in consideration Approx. 380ºC
Approx. 380ºCof heat effects
Film thickness
Base finishing
can be adjusted. requires care.
Sealing
When the film
Characteristics
condition can be thickness is thin,created.
the base conditions
Complex shapes directly affect thecan be formed.
painted surface.
Limited depending Limited depending
on electric
on electricSizefurnace’s size
furnace’s size
Approx.
Film thickness
Thickest
30μm ―１mm
LifespanMediumSheet lining
Fixing using
adhesives
200ºC or lower

and other chemicals under high temperature.
③ PTFE‌
can be eroded in high temperature 80%
metal hydrogen compounds including 80%
NaOH, KOH, B 2H 6, aluminum chloride, andammonia.
④ ‌PTFE is gradually damaged by nitric acid at

Film thickness is
uniform.
Unsuitable forcomplex shapes.
Up to sizes that allow
road transportation ineach country.

Short

250ºC under pressure.
The usable temperature range of PTFEs can be
designed depending on the fluid used and yourconclusion as to the conditions under which PTFE
cannot be used. However, a general understanding of

2T ― 4T

the usable temperature is as follows.

Long

ETFE may crack under stress from chemicals otherthan those listed above. In addition, PVDF has overall

5. Heat‌
resistance and chemical
resistance of fluororesin sheet lining

inferior chemical resistance, and is eroded by solventswith strong polarity in particular.

Heat resistance

Summer 2018

Regarding heatproof temperatures of fluororesin sheet
lining, there are two standards specified by VALQUA:
120ºC : ‌a d h e s i v e l i n i n g （ d e p e n d i n g o n t h eheatproof temperature of adhesives）
150ºC : ‌loose lining（depending on the heatproof
temperature of PFA welding）

No.35

Table4

Reagent

Hydrochloric
acid

10%
20%

Unlike lining piping, loose lining is a construction
method in which a liner is not attached to a can.

Nitric acid

10%

Therefore, loose lining is used under limited conditions.
In addition, the balanced type of loose lining was

Sulfuric acid 30%

developed to withstand negative pressure by using aloose lining. With the balanced type, vacuuming of theliner’s indentations from vent holes is prevented; it isfrequently used under negative-pressure conditions athigh temperature between 120 and 150ºC.
Chemical resistance

Table4 shows the effects of acids, alkalis, and solventson the weight increase of PTFE. PTFEs do not reactwith most industrial chemicals and solvents and havevery strong chemical resistance. However, PTFEs
react with the following chemicals:① ‌Alkali metals in the molten condition（including
sodium, potassium, and lithium）remove F
atoms from polymers.
② PTFEs react with fluorine gas, chlorotrifluorine,
19

Chemical propertiesａ）Effects of acids and alkalis
Ef
f
ec
t
so
fac
i
dsandal
kal
i
sonwe
i
gh
ti
ncr
easeo
fTe
f
l
on®PTFE

Sodiumhydroxide
Ammoniumhydroxide

10%
50%
10%

Exposuretemperature℃

Dipping time

Weightincrease％

25
50
70
100
200
25
70
25
70
100
200
25
70
100
200
25
70

12 months
12 months
12 months
8 hours
8 hours
12 months
12 months
12 months
12 months
8 hours
8 hours
12 months
12 months
8 hours
8 hours
12 months
12 months

0
0
0
0
0
0
0.1
0
0
0
0.1
0
0.1
0
0
0
0.1

・‌These values are obtained when virtually achieving equilibrium.
The values are assumed not to significantly increase even if the
exposure time is increased.
・‌Weight changes of 0.2% or smaller are within study error values.
・‌Regarding studies conducted at temperatures over reagents’boiling points, these studies were conducted within sealed
vessels, so the pressure is obtained at its vapor pressure at thetemperature.

Technical Papersｂ）Effects of solvents
Effects of solvents on weight increase of Teflon®PTFE
Solvent
AcetoneBenzeneCarbontetrachloride

Ethyl alcohol（９５％）

Ethyl acetate

TolueneExposuretemperature℃

Dipping time

Weightincrease％

25
50
70
78
100
200
25
50
70
100
200
25
50
70
100
200
25
50
70
25
50
70

12 months
12 months
2 weeks
96 hours
8 hours
8 hours
12 months
12 months
2 weeks
8 hours
8 hours
12 months
12 months
2 weeks
8 hours
8 hours
12 months
12 months
2 weeks
12 months
12 months
2 weeks

0.3
0.4
0
0.5
0.6
1.0
0.6
1.6
1.9
2.5
3.7
0
0
0
0.1
0.3
0.5
0.7
0.7
0.3
0.6
0.6

In most cases of fluororesin sheet lining, an adhesivelining method is used.
Fluororesins are non-adhesive. Therefore, the surfaceof the fluororesin repels adhesives when applied to thesurface. This non-adhesive property prevents
fluororesin sheets from sticking to a can body, so
surface modification of the adhesive surface inadvance is required. Surface-modification methods
include: chemical treatment（hereafter called“surface
treatment”）, glass-backing sheet, and plasma etching.
However, lining sheets mainly use the first two
methods.
In surface treatment, metallic sodium is melted inammonia solution or naphthalene solution, then the
resulting solution is used to etch the surface. Sodium
ions are made to react with fluorine molecules to form
NaF. A carbon layer is precipitated on the surface.
The adhesive surface after surface treatment turns
dark brown and loses non-viscosity. The adhesive
structure is“carbon layer –（adhesive）– metal.”
Glass-backing sheets are manufactured through a

Summer 2018

・‌These values are obtained when virtually achieving equilibrium. The
values are assumed not to significantly increase even if the
exposure time is increased.
・‌Weight changes of 0.2% or smaller are within study error values.
・‌Regarding studies conducted at temperatures over reagents’boilingpoints, these studies were conducted within sealed vessels, so thepressure is obtained at its vapor pressure at the temperature.
Note : ‌Teflon®Properties Handbook, Du Pont-Mitsui Fluorochemicals
Company, Ltd. １）

6. Process of fluororesin sheet lining

lamination method, which proceeds as follows: 1）A
The order of chemical resistance of resins is as

PFA sheet is heated above its melting point. 2）A

follows:

glass cloth sheet is pressed into the PFA sheet.

ＰＴＦＥ＝ＰＦＡ＞ＦＥＰ※＞ＥＴＦＥ＞ＰＶＤＦ

3）The resulting sheet is cooled for integration. In the※ There are few FEP linings.

case of a PTFE sheet, its melt viscosity is too strong

Regarding construction methods of linings, the orderfor this press-in approach, and so a lamination process

is as follows:is conducted via a PFA film.

Sheet lining＞ Rotational molding＞ Coating
When corrosion resistance is taken into account, theFigure2 shows the processes of fluororesin sheet
lining.

maximum service temperatures are as follows.
Coating products：80‒100ºC
ETFE rotational molding：100℃
PFA rotational molding ：120℃
PTFE/PFA-lining products
Adhesive lining：120℃（adhesive’s limitation）
Loose lining：150℃（welding-joint products）
Note：‌These results do not apply to special liquidchemical specifications. Also, the lifespan will
differ under long-term use.

20

No.35

Lining Tank（Basics）①Acceptance①受入検査
inspection② Can body
②缶体清掃
cleaning
缶体セッティング
Can
body setting③ Adhesive③接着剤塗布application⑪シート⑪ Sheet貼 付
application⑬⑬ノズル
Nozzle貼 付
application⑭⑭溶接
Welding⑮ Pinhole⑮ﾋﾟﾝﾎｰﾙﾁｪｯｸ
check⑯ Band⑯帯溶接
welding⑰⑰仕上げ
Finishing

缶 体bodyCan④Acceptance④受入検査
inspection

ふっ素樹脂
Fluororesin
シート
sheet

⑥ Adhesive⑥接着剤塗布application

断⑤⑤裁
Cutting⑱接着⑱Adhesion

Trunk,
manhole胴部・マンホール⑦⑦裁断
Cutting⑨ Surface⑧⑧癖付け
Shaping ⑨表面処理
treatment⑲ Completion⑲完成検査
inspection

洗 浄⑳⑳
Washing

包 装
21
Packaging⑩ Adhesive⑩接着剤塗布application

Panel
鏡 部
⑫ Acceptance⑫受入確認
confirmationノズル
NozzleFigure2① ‌Acceptance inspection of a can body：⑮ Pinhole check：‌Inspection after manufacturing of the can	The can body is checked for welding flaws.

body is completed. In particular, it is⑯ Belt welding：important to confirm the tie-in position and（‌Robot welding; details are explained indirection of nozzles, etc. The inside is“Application.”）

Summer 2018

blasted after the inspection is completed.
② ‌Can body cleaning：‌Cleaning of the surface to which an adhesive
is applied is important, as it affects adhesion.
③ Adhesive application：‌An adhesive is applied to the can body.

No.35

Lining process④ Acceptance inspection of fluororesin sheet：
Documents are checked.
⑤ Cutting of fluororesin sheet：Cut to the given size.

⑰ Finishing：‌‌	‌The sealing surface is finished with a central
focus on the welded area of the flange parts.
⑱ Adhesion：‌
A lining sheet is attached to the can body.
⑲ Finished-product‌inspection：‌	Inspection is made according to in-housestandards.
⑳ Washing,‌
packing, shipping⑥ Adhesive application to fluororesin sheet.
⑦ Cutting of panels：Ends of the panel are cut.

Among these processes, the welding process is the⑧ Shaping of panels：‌most important regarding quality. The number of	‌Panels are shaped in a unique pattern throughwelding processes is proportional to the length of thevacuum molding.
	‌Details are explained in“Application.”can body. Therefore, for these processes, adequate
time is allocated in the construction schedule.

⑨ Surface treatment of panels⑩ Adhesive application⑪ A lining sheet is attached to the can body.
⑫ ‌Acceptance inspection of nozzle:	Whether the nozzle is manufactured to thegiven size is checked.

7. Considerations when designing
fluororesin lining tanks
The considerations when designing fluororesin liningtanks are explained below.

⑬ Nozzle application：

The major differences in constructing fluororesin lining	The nozzle is applied to the can body.

tanks compared with metal tanks are that metal burrs⑭ Welding：‌The nozzle is connected to the can bodyand welding do not damage fluororesin liners, and theby welding（manual）.
21

method of setting angle R to maintain adhesion.

Technical Papers

７-1）Types of tanks
Pressure container

Storage tankNozzle’s
convex angle

Bottom concave angle

Figure4 Construction of convex and concave parts in corners

Tower

ISO container andtransportation vessel・‌‌Uent holes on a can body should be perforated. Vent
holes have the following functions: 1）To allow theescape of gas which accumulates behind the lining
material and through which liquid chemical in thetank may permeate and be discharged from theoutlet, and 2）To serve as leakage detection holes in
the case of lining breakage. Consultation is required
regarding the mounting positions and number.

Figure3

Types of tanks

・‌Regarding panels, 10% plate panels are generally７-2）Applicable manufacturing range

bodies of other shapes and sizes, independent

Manufacturing involves coordinating the design andconsultation is needed.

manufacturing of the metal can bodies, and applying・‌Since workers must enter the tank during

the fluororesin sheet lining on the inside surface of theconstruction, the can body should have an opening

tank. When a can body is classified as a type 1 or 2

on the main-body flange or a manhole of φ500 orpressure container, or is subject to the Fire Service

greater should be placed. In addition, for tanks

Act, tests by government agencies should beof 10m 3 or greater, two manholes are placed as

conducted before lining.

standard.
・‌Structures within the tank should be simple. When

７-3）Summary of lining designbaffles or supports are mounted, consultation is・‌In principle, when a can body is divided into a trunk

required.

（torso）and upper lid, or into a trunk and trunk, aflange connection should be used.

・‌If the metal pipes of nozzles protrude into the canbody, a sheet lining cannot be used. Therefore, the・‌‌Unlike general metal tanks, the lined surface of ashape should be as previously described as antank should be smooth without convex or concave

example of the convex angle of a nozzle. In addition,

parts. Metal weld beads within the tank should be

as standard, the height of a nozzle is 100 mm fromsmooth.

the outer surface of the can body.

・‌The convex angle of the treated surface should be・‌The lining of the flange surface of a nozzle is not flat-

R-shaped; the concave angle should have a slope

face lining due to construction convenience;and large R. In addition, regarding the nozzle angle

basically, seal-face shapes are used on the inside of aR, each size has standards ranging from R3 to R5.

bolt.
・‌In principle, lining construction is conducted on aturning roller. If nozzles or attachments interfere,
relocation is sometimes required.
22

Summer 2018used for sizes between φ500 and φ2000. For can

No.35

Lining Tank（Basics）

8. ‌Considerations when designing
fluororesin sheet lining vessels

pressure exceeds 29.4 MPa, gasket parts andflare parts may be damaged.
③ ‌The gasket factor for Valflon jacketed gaskets

１．The service temperatures include reaction heat and（No. N7030-T5N and No. N7035-T5N）is m = 3.5 ;dilution heat, and so vessels should be used at

the minimal fastening pressure is y = 14.7 N/mm2.

120ºC or lower.（If the temperature is over 120ºC,④ ‌Regarding the initial fastening contact pressure

independent consultation is required.）of gaskets, stress relief develops in areas

２．In principle, vessels cannot be used under negative

including flare parts. Therefore, additionalpressure. If they are, countermeasures againsttightening should be conducted without fail at

negative pressure should be applied to the vessels.

the following times:

Therefore, when draining a liquid which is

		 ・Three to four hours after initial tightening

contained within a vessel, operation which

		 ・Before operation

prevents negative-pressure conditions within the		 ・‌In particular, when restarting operation under

vessel is required, such as pressurization draining

a thermal gradient⑤ ‌Spring washers should be used with bolts.

or vent opening.
In addition, when vessels are used under heating
conditions, the pressurized condition or ventopening is required until the temperature returns

Summer 2018
No.35

to room temperature.
3．Never weld towers and tanks after lining.

9. Conclusion
Some of our lining tanks have been used for morethan 20 years, and so are not expensive in view ofIn addition, when welding is conducted near afunctionality and lifespan.

vessel, take countermeasures to prevent sparks

In the next article,“Applications,”we will focus on the

striking the lining surface, such as covering thecharacteristics of our lining construction, thevessel with a flame repellent or relocating themechanism of liquid chemical permeation, andwelding area.

effective countermeasures against liquid chemical

4．① ‌For joining-flange areas of lining equipment,

permeation.

Valflon jacketed gaskets（No. N7030-T5N,
No. N7035-T5N, and No. N7031-T5N）are
recommended.

10. References② ‌A vessel should be managed within the１）‌Teflon® Properties Handbook, DuPont-Mitsui

tightening contact pressure of the gasket

Fluorochemicals Company, Ltd., 2001 version.

（recommendation）ranging from 14.7 to 19.6

Note：“‌Teflon®”is a registered trademark of The

MPa; bolts are fastened uniformly on several

Chemours Company（U.S.）.

occasions. During fastening, if the contact

Tomoyuki Kikukawa
Assistant To High Performance
Plastics Product Manager

23

Atsuyoshi Iwata
Corporate Research andDevelopment Group
Product Development Division Ⅱ