Summer 2018No.35
http://www.valqua.co.jp● Greetings・
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Senior Executive Officer Director of Corporate Research andDevelopment Group Mutsuo Aoki

● Customer Solutions

Seal Training for Maritime Technique Training inCompliance with an International Convention（STCW Convention）・
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・2
H&S BUSINESS GROUP Takahiro Yamamoto● Customer Solutions（Contribution）

Cleaning Plant Facilities Using a Low-Pressure
Composite Water Flow Cleaner（Cavitation Cleaning）・
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・5
Blue Engineering, LTD. Masaru Kitagawa● Technical Papers

Design Guidelines and Troubles for DYNAMICBELLOWSTM
and Countermeasures・
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・9
Sales Group Technical Solution Division Masafumi Ina● Technical Papers

Lining Tank（Basics）
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・16
Assistant To High Performance Plastics Product Manager

Tomoyuki Kikukawa

Corporate Research and Development Group
Product Development Division Ⅱ Atsuyoshi Iwata● Product Introductions

Substitute Sealants for Refractory Ceramic Fiber・・・・24
Corporate Research and Development Group
Product Development Division Ⅰ Masato Hamade● Product Introductions

Sheet Gaskets for High-Temperature Use
VALQUA HEAT RESIST SHEET™ No.HRS・
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・29
Corporate Research and Development Group
Product Development Division Ⅰ Satomi Takahashi● Recent Technology News Back Issues・
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・33
● From Nippon Valqua Industries, Ltd. to VALQUA, LTD. ・
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・34

GreetingsThank you for your continuing interest in our magazine.
In 2018, VALQUA initiated the 8th medium-term management plan NVS8. As with NVS7, this newplan will continue to focus on activities to offer total solutions in the Seal Engineering Services..
Through such activities, as an H & S company we will maximize customer value, and through thenew plan we will use innovations based on H & S. This will help us create new solutions that drive
solid and sustainable growth in global markets. To reflect this intention, we removed the two words“Japan”and“Industry”from our company name“Nippon Valqua Industries, Ltd.”and renamed thecompany“VALQUA, LTD.”.

Summer 2018
No.35

VALQUA is striving to be innovative in global markets which continue to evolve rapidly. To achieve
this goal, we are expanding our technical development. We also strive to deliver the results of ourtechnological development as early as possible to respond to demands from all customers. We aim tocreate new solutions which are valuable for customers through actively introducing methods such as
open innovation, and combining accumulated technological know-how with leading technologies, thus
satisfying our customers’needs as a true H & S company. This is our overall technical development
goal, and we will pursue ingenuity to achieve it.
From this issue, Valqua Technology News consists of three parts: 1）Customer solutions, 2）Technicalpapers, and 3）Product introductions. The VALQUA group will develop new products based on
sophisticated technologies, evolve these new products through H & S, and offer customer solutions.
With this new magazine structure, this issue introduces several cases of what kinds of achievements
can actually be made. We hope it will clearly show the process of creating H & S solutions, throughwhich the VALQUA Group contributes to customers’security and safety. We would also be pleased if
readers find the issue to be a useful technological reference.
We hope that you will continue to enjoy Valqua Technology News along with VALQUA products andservices.

Senior Executive Officer Director of Corporate Research and Development Group1

Mutsuo Aoki

Customer Solutions

Seal Training for Maritime TechniqueTraining in Compliance with an International
Convention（STCW Convention）
1. Introduction

obtained certification, and the background which led
to the enactment of an international convention on

Sealing engineering is a core technology of VALQUA

seamen’s skills. Based on these, as well as the efficacy

which has been developing solutions for the issues facedof Certification of Maritime Education & Training, we

by customers amid the changing times. Recently, we aim

explain the seal training.

to provide customers with essential sealing engineering
services. To achieve this goal, we have been actively
developing and providing our original services.

2. Nippon Kaiji Kyokai
The Japanese classification society Nippon Kaiji Kyokai

training service, which we aim to introduce in various

is internationally known as ClassNK. ClassNK aims toindustries and areas, and completed the development

secure safety regarding human life and property in theof a maritime technique training in October 2017, as

marine environment and to prevent marine pollution.

described in this article.

With these missions, ClassNK’s business includes theThis training has now obtained Certification offollowing: 1）Registration and inspection of ships’

Maritime Education & Training（Figure1）
from Nippon

classification, for which classification societies are

Kaiji Kyokai（ hereafter called“ClassNK”）. Thisresponsible, 2）Certification of management systems

training complies with the STCW Convention, anbased on international standards including ISO, and 3）

international convention. Currently, two training bases

Certification of Maritime Education & Training inare certified, one in Machida, Tokyo and the other incompliance with international conventions. ClassNK has

Gojyo, Nara.

a history of more than 110 years, has the largest numberThis article explains ClassNK, from which weof ship classifications（approximately 20% of overall shipclassifications among more than 50 classification societies
worldwide by March 2018）, and an international
reputation.

3. The STCW Convention,
an international convention
To prevent maritime accidents resulting from seamen’slack of skills regarding ship operation, an international
convention called the STCW Convention （TheInternational Convention on Standards of Training,
Certification and Watchkeeping for Seafarers, 1978）,Figure1 ClassNK’s Certification of Maritime Education & Training

which sets standards for skills and knowledge, was2

Summer 2018

We have been expanding seal training as a skill

No.35

Seal Training for Maritime Technique Training in Compliance with an International Convention（STCW Convention）

2010
Revision of Convention
Manila Amendments

1978

Seamen’s competence was standardized
based on STCW Convention Standards
regarding engine departments（A-3-1）, anddescribes abilities related to seals.
Seamen’s competence

present

Past

the handling and knowledge of seals as on-the-job

Non-Japanese/
Filipino crews

STCW Convention standards

Filipino crews
Country of origin

including new employees, depend on the information
on sealing skills and knowledge handed down by older
workers.
Over many decades, VALQUA has accumulated much

Seamen’s competence varies depending on
nationality.
Seamen’s competence

Stranding of an oil
tanker in the English
Channeltransportation company provides its own education on
training during voyages. Inexperienced seamen,

Japanese crews

I M O（ I n t e r n a t i o n a lStandard Organization）
adopted the STCW
Convention.

1967

Therefore, after hiring seamen, each marine

Japanese crews
Non-Japanese/
Filipino crews

Filipino crews
Country of origin

Figure2 Background resulting in establishment of the STCW Convention

knowledge on sealing materials at VALQUA andcustomers’ sites, which it uses to provide sealing
engineering. Seal training was developed based on
sealing engineering, and is intended to ensure thatparticipants acquire optimal techniques for selecting andconstructing sealing materials. The training is practical:
participants learn knowledge and acquire techniques

Summer 2018
No.35

adopted, thus standardizing seamen’s skills. In thethrough practice. Also, unique characteristics of thepast, qualification systems regarding seamen’s skills

training not found in other types of training include

and competence varied among countries, and sovisualizing individual skills through an original system,

seamen’s abilities also varied. However, after anand hands-on construction education in which various

accident in 1967, seamen’s technical standards wereon-site techniques are simulated. This training has

revised mainly by the International Maritime

received positive feedback as being effective for seamen

Organization（IMO）. Then, in July 1978, the STCW

（navigation officers, engineers, and crews）from marine

Convention was adopted and international standards

transportation companies as off-the-job training, and isregarding seamen’s training and qualifications weresuperior to on-the-job training.

set （Figure2）.

As mentioned above, this training targets seamen

The STCW Convention’s Code A shows seamen’s

mainly related to the STCW Convention（navigation

obligation and abilities. A-3-1 of Code A describes

officers, engineers, and crews）. However, ClassNK

1）

In addition,

recognized the need to ensure security and safety forbased on this convention, the IMO started the IMO

not only marine transportation companies but also for

Model Course as a basic training program to encourage

all those involved in ships and vessels. Therefore, theeffective training, which includes more detailed

training is also provided for those engaged in ship-training methods. Sealing skills are indispensable forrelated works（shipbuilding, ship maintenance, public

３）organizations including maritime training institutions）,

skills and knowledge regarding sealing.

the safe operation of ships.

２）

and those handling ship devices and equipment.

4. ‌Seal training for maritime
technique training

The curriculum of the two-day course covers bothclassroom education and practical training on gaskets,rotary seals including gland packing, and mechanical

To become a seaman, a seaman’s competency certificate

seals. After participants complete this training, theiris needed, for which special education at institutions

understanding is then tested, and each successful

including universities is needed. Such institutions

participant is issued a ClassNK-certified certificate ofissue the certificate. However, the knowledge andcompletion（Figure3）.

skills required differ depending on the type of seaman,and so the time allocated to sealing is limited.
3

Customer Solutions

offer ClassNK-certified training. We encourage

Classroom
education

Practice

Basic knowledge
・Functions of gaskets
・Types of gaskets
・Selection methods・‌Construction theory,etc.

Construction/
response methods
・Fastening methods
・Creep mitigation
・Effects of flanges
・Sealing properties

Japanese marine transportation companies toparticipate in the training. We also have similar
training bases in China, Taiwan, Vietnam, Thailand,
and South Korea, where we will arrange a training
system to offer certified training.
We also offer sealing engineering services including
seal training as a skill training service. Based on these
services, we will contribute to the development ofConfirmation test
Confirmation tests throughwritten examination

Acquisition of knowledge
and skills

world marine transportation markets and to thesecurity and safety of the industry.

6. References
１）‌Seamen’s qualification based on STCW Convention,etc., Ministry of Land, Infrastructure, Transport andTourism, http://www.mlit.go.jp/sogoseisaku/kotsu/
bunya/kaiji/stcw.html

Figure3Curriculum summary

5. Conclusion
Currently, VALQUA has two training bases, one in２）‌2010 STCW Convention（Manila Amendments）inEnglish and Japanese（official translation）, supervisedby the Maritime Bureau, Ministry of Land,
Infrastructure, Transport and Tourism, published by
Seizando-Shoten Publishing Co., Ltd.

Summer 2018

Issuance of certificate of completion（ClassNK-certified）

３）
‌（Model course 7.04）Officer in charge of an
Engineering Watch, 2014 Edition

No.35

Machida, Tokyo and the other in Gojyo, Nara, which

Takahiro Yamamoto
H&S BUSINESS GROUP

4

Cleaning Plant Facilities Using a
Low-Pressure Composite Water Flow
Cleaner（Cavitation Cleaning）
1. Introduction

Summer 2018
No.35

Cleaning had been performed on-site simply by blowing
air into water pipes. Due to clogging since the machine

A low-pressure composite water flow cleaner physicallywas installed, the product molding cycle of the mold had

removes sludge that has adhered to the inside surface ofincreased from the initial 113 seconds to 123 seconds orwater pipes by using water and air. The cleaning

longer. For the analysis, pre-cleaning and post-cleaning

process does not use any high-pressure water, chemicals,conditions were compared as follows: ⑴ Parts wereor chemical reactions. Previously, such removal required

produced at the mold’s passing water flow rate and at

dismantling, liquid-chemical management, and liquid

the initial condition of 113 seconds. ⑵ After the mold’s

disposal, all of which are costly. Thanks to the cleaner’s

temperature stabilized, the temperature was measured

system, the sludge removal does not involve any

using a thermograph. ⑶ The mold’s temperaturedismantling or chemicals, thus achieving low-cost, eco-

distribution and defects of molded products before

friendly cleaning.

cleaning were compared with those after cleaning.
【Discussion】

2. Cleaning method

The overall flow rate was improved as shown in
Table1. Before cleaning, two surface sink marks

A hose with a pressure resistance of at least 0.8 MPa isdeveloped as shown by circles in Figure1. Whenconnected to the“IN”and“OUT”ports of the

manufacturing parts, a molding cycle of 123 seconds

equipment to be cleaned. Water is fed at 0.4 MPa into

was required. However, after cleaning, the temperature

the hose, while being mixed with fine air bubbles which

distribution of the mold improved, the surface sinkserve as centers for cavitation. In addition, the direction

marks disappeared, and the defects were resolved.

of water flow is rapidly reversed to create shock waves,

Also, the overall temperature was lower. However, thewhich make the fine air bubbles swell and contract,temperature of some areas increased due to changes incausing cavitation. Also, the air bubbles act as dampers,

the resin flux. Therefore, the molding cycle should bethus helping to control the cavitation force. Therefore,

made longer than the initial cycle. Through thecleaning can be executed without damaging theextension, the temperature of such areas was lowered.

equipment to be cleaned.

As a result, we showed that parts could be produced
without problems at a molding cycle of 115 seconds,

3. ‌Cleaning effects of resin
molding-die water pipes

which is just 2 seconds longer than the initial condition.
【Results】

The molding cycle was shortened by 8 seconds. We

This section introduces the case of a customer. The

found that regular cleaning of the mold eliminatedcustomer uses an 850T-class molding machine to moldperforation troubles and achieved stable production.

panel parts, and the mold which we cleaned had beenAlso, unlike chemicals, the cleaning process is not

manufactured 7 years ago and then used for production.

associated with melting, and thus frequent cleaning

5

C u s t o m e r S o l u t i o n s 《C o n t r i b u t i o n 》

equipment, and rotatory blowing machinery. With

does not damage the mold.

these findings, the machine is expected to be used also
in the PET bottle industry. Regarding other uses, themachine is used for cleaning the water pipes ofcastings including aluminum die castings. Althoughutilization in plants is limited, we have received
positive customer feedback. Relative to the effects ofchemical cleaning at 100%, the cleaning effect of themachine is 80%. Sometimes, chemical cleaning causes
problems for production lines such as chemicals
remaining in the lines when production restarts.
Figure1

Table1‌Pre-cleaning
temperature distribution of the moldand defective areas

However, with our cleaning machine, no troubles have‌
Numerical
comparison of pre-cleaning and postcleaning conditions

tube-type heat exchangers（on the side of the shell）,

been reported. In addition, when cleaning shell- andonly the surface can be cleaned even though a

Endpoint
Overall flow rate
（0.2MPa）
Circuit 1

Pre-cleaning

Post-cleaning

59.6L/min

74.6L/min

1.1L/min4.2L/minCircuit 2

8.1L/min10.3L/mintubes. Such characteristics have been positively

Circuit 3

3.2L/min5.3L/minCircuit 4

5.4L/min

7.0L/minevaluated. Since this machine enables plate-type heat

Circuit 5

10.8L/min

12.5L/min

Sub-circuit 1

16.9L/min

19.5L/minhave received positive feedback such as about thelower cost of exchanging packings.

14.1L/min

15.8L/min123seconds

115seconds

Defective molding（At initial condition）

Surface sink marks
developed.

No defect

cleaning machine can also clean the space between

exchangers to be cleaned without dismantling, we

Summer 2018

Sub-circuit 2
Molding cycle

hyperbaric cleaning method is used. However, our

5. Effects of plant facility cleaning

4. Sales of the cleaning machine5-1）‌Effects for a shell- and tube-type heat

Although we have limited results regarding sales for

We cleaned a horizontal-type shell- and tube-type heatplants, we have a number of successful sales for theexchanger shown in Figure2. Before cleaning, a reddish-resin-molding industry, and particularly with automobilebrown deposit covered the side of the shell as shown inparts manufacturers. The cleaning machine is applicable

Figure3. The deposit was such that the red deposit

to water pipes, not only cast pipes but also those under

could be removed by scratching with a finger. The

the molding machine’s hopper and in the chiller’s heatcleaning machine’s“IN”and“OUT”were connected to

exchanger. Therefore, the machine can be used forthe handholes and cleaning was conducted without

various purposes. Recently, the cleaning machine

removing the“IN”and“OUT.”During cleaning, a large

reduced the cleaning time from approximately 3 days toamount of deposit precipitated in the tank as shown in

24 hours at a PET bottle factory, where previously it

Figure4. This precipitate rapidly clogged the filters as

was necessary to dismantle pre-form molding dies andshown in Figure5. A considerable amount of deposit

the take-out devices’water pipes in order to clean

could be removed. In addition, when we confirmed thefacilities.

post-cleaning conditions of the connection outlets, we

In addition, we found that the cleaning machine canfound that deposit had been thoroughly removed as

be used for cleaning the water pipes of sintering

shown in Figure6, since these areas were exposed tomachines for pre-formed screw parts in manufacturing

powerful flows.

exchanger（horizontal-type）

6

No.35

Cleaning Plant Facilities Using a Low-Pressure Composite Water Flow Cleaner（Cavitation Cleaning）

5-3）Effects‌
for a large plate-type heat exchanger
As Figure9 shows, the cleaning machine was connected
to a large plate-type heat exchanger with a plate numberof 410 and a heat transfer area of 391.7m2 without
dismantling. Then, we conducted cleaning for 50 hours
Figure2 ‌Shape of heat exchanger

Figure3 Pre-cleaning conditionon the cooling-water side and for 70 hours on thecirculating-water side.
The results are shown in Table2. The flow rate of
circulating water was sped up by approximately 45%
and the heat exchange amount was increased byapproximately 75%. Since the plates were not dismantled,
the packing did not need to be exchanged. Customers
appreciate such benefits.

Figure4 During-cleaning condition

Figure5Filter condition
Cooling water（IN）
Cooling water（Out）

Summer 2018

Cleaning
water tank

Figure9
Figure6 Post-cleaning condition

5-2）‌Effects for a large shell- and tube-type
heat exchanger

No.35

Before cleaning, as shown in Figure7, the spaces
between tubes were clogged with oxide. However, after
cleaning, as shown in Figure8, the clogging was

Table2

Low-pressurecomposite waterflow cleaner

Schematic drawing of the connection‌
Numerical
comparison of pre- and post-cleaning
conditions for a large plate-type heat exchanger
Heat
Cooling water
Circulating water Circulating Heatwater exchange transmission
temperature（℃） temperature（℃） amount amount rateＫｃａｌ/
IN OUT Disparity IN OUT Disparity ｍ３/ｈｒ Ｋｃａｌ/ｈｒ㎡・ｈ・℃

Pre７ ３５．
３ ６．
６ ４７．
０ ４２．
３ ４．
７
cleaning ２８．
Post- ２７．
５ ３６．
０ ８．
５ ４５．
５ ３９．
８ ５．
７
cleaning

１５０ ７０５０００ １４３
２１６ １２３１２００ ２９０

removed. The oxide covering the tube surface was notcompletely removed. However, when the heat exchange
conditions during operation were measured, we foundthat the cleaning was effective.

5-4）‌In-line cleaning of a small plate-type heatexchanger for spa facilities
Although the conditions are different from those ofplants, plate-type heat exchangers are also used at spa
facilities, which sometimes suffer clogged water pipes.
When this happens, they have to dismantle and clean
the heat exchangers. Accordingly, we used an in-line
cleaning machine（which is less effective than an offline machine）to clean a small plate-type heat exchanger.

Figure7 Pre-cleaning condition

Figure8 Post-cleaning condition

During the cleaning, we opened the plates andconfirmed the conditions. The cleaning machine wasconnected to the heat exchanger and the plates were
washed for 2 hours as shown in Figure10.
Before cleaning, the entire plates were covered withdeposit as shown in Figure11. However, after the7

C u s t o m e r S o l u t i o n s 《C o n t r i b u t i o n 》

cleaning, approximately 80% of the plate surface could
be seen, as shown in Figure12. Thus, the cleaning

6. Conclusion（Expansion to plants）

restored the heat-exchange amount and resolved theUntil now, plate-type heat exchangers and shell- andpressure loss, returning the equipment to normal

tube-type heat exchangers（on the side of the shell）

operation.

have been cleaned with chemicals or high-pressure

Connection of cleaning machine
Spa’s
water
storagetankwater or had to be replaced since such areas could not

Plate-type
heatexchanger

be dismantled. We have started developing a large
cleaning machine（NR-2000）together with VALQUA
Warm
water

DrainagechannelAlso, when cleaning plant facilities, the channel areas
are expected to be large. Therefore, the effects of
bubbling through a two-layer fluid and turbulence

Bathtub

Figure10LTD., which we expect will overcome such problems.

Connection of cleaning machine

effects, which develop from switching the flow
direction, can exert powerful cleaning rather thanwith cavitation, which occurs during cast cleaning.
Therefore, we need to continue studying physicalphenomena regarding cleaning effects.

Summer 2018

Figure11 Pre-cleaning condition

Figure12 Post-cleaning condition

No.35

Masaru Kitagawa
Blue Engineering, LTD.

8

Design Guidelines and Troubles
for DYNAMICBELLOWSTM andCountermeasures
1. Introduction

catalog, but for Bellows that absorb displacement
perpendicular to the axis and in a bending direction,

The functions of welded metal DYNAMICBELLOWSTM

selection is often difficult.

（hereafter“Bellows”）are to absorb displacement

Also, when the Bellows’inner pressure is greater thanparallel with the axis, perpendicular to the axis, and in

the outside pressure to maintain airtightness, bucklinga bending direction as shown in Figure1. The Bellows

sometimes develops as shown in Figure2, resulting inabsorb displacement while maintaining airtightness.

the risk of deformation and breakage. Therefore, care

When selecting Bellows that absorb displacement

is required when designing.

parallel with the axis, it is easy to select from theSummer 2018
No.35
Displacement parallel with axis（Δx）

Before buckling

Figure2

After buckling

Bellows’buckling

In addition, when Bellows are attached in a horizontal
direction, the Bellows’own weight causes horizontal
deflection as shown in Figure3. Therefore, care isrequired like the case of buckling.
Displacement perpendicular to axis（Δ y）

Horizontal deflection

Displacement in bending direction（Δθ）

Figure19Types of displacement

Figure3

Bellows’horizontal deflection

Technical Papers

This article examines the case of our standard

In this case, Equation（1）becomes:

product V series（catalog No. PC08）, and describes theselection method for Bellows that absorb displacement…………（３）

perpendicular to the axis, and design considerations
for buckling and horizontal deflection.

Equation（2）becomes:

2. Design guidelines for Bellows…………（４）2-1）‌Concept of displacement perpendicular

However, Δ x is displacement parallel with the axis

to the axison the contraction side（mm）.

When investigating the Bellows’displacement
perpendicular to the axis, first the displacement

Regarding Sections 2-1）and 2-2）
, the shape of Bellows

perpendicular to the axis is converted into thewith displacement perpendicular to the axis is suchdisplacement parallel with the axis, using the equation:that expanded parts and contracted parts are combined
as shown in Figure4. Therefore, regarding the…………（１）
where, Δ x（y）：‌value converted into displacement

Summer 2018

parallel with axis（mm）
D：Bellows’outside diameter（mm）

Δ y ：‌displacement perpendicular toaxis（mm）
L：Bellows’length（mm）
When the converted allowable displacement parallelwith the axis is known, the allowable displacement

Before application of displacement

No.35

perpendicular to the axis can then be calculated by
the equation:…………（２）where, Δ y（max）：‌allowable displacement
perpendicular to axis（mm）.
2-2）‌Combination of displacement parallel withaxis and displacement perpendicular to axis
In Section 2-1）
, only displacement perpendicular to theaxis was given. However, generally, Bellows are often

After application of displacement

used with both displacement perpendicular to the axis
and displacement parallel with the axis. According toEquation（1）, the smaller L is, the larger the converted

Expansion side

displacement parallel with the axis Δ x（y）. Therefore,

Contraction side

the calculation should be made to minimize L under
the influence of displacement parallel with the axis.

Figure4

Shape of displacement perpendicular to axis
10

Design Guidelines and Troubles for DYNAMICBELLOWSTM and Countermeasuresconverted displacement parallel with the axis Δ x（y）,

length = 15mm, Contraction length = 5mm

allowance ranges should be prepared for both the

In this case, the Bellows length L = 10mm, Δ x =±5mm.

expansion side and the contraction side.

According to Equation（2）,Therefore, a Bellows with a length of L is given thevalue of“＋Δ x（y）and‐Δ x（y）.”
In the case of 2 blocks:

3. Selection procedure for V series

Expansion and contraction length = 20mm, Expansion

3-1）‌When only displacement perpendicular

In this case, the Bellows length L＝20mm, Δ x = ±10

to the axis is present
Based on the design guidelines described above, we

length = 30mm, Contraction length = 10mmmm.
According to Equation（2）,consider the selection of V series（Catalog No. PC08）.
Refer to the catalog and follow the steps.
Figure5 shows the selection flow. Each step is described

In the same manner, increase the block number andbelow.

calculate for each block number. Table1 shows theresults.

【Step 1】Select Bellows’ size（nominal diameter）

Summer 2018

【Step 2】‌Calculate allowable displacement perpendicular
to axis for each block number【Step 3】‌Select the type which can accommodate thenecessary displacement perpendicular to axis

Figure5

No.35

Selection procedure for V Series

Table1

V20’s block number and displacement amount

Block number

1

2

3

4

5

L（mm）

10

20

30

40

50

Δ x（mm）±

5

10

15

20

25

Δ y（max）
（mm）

0.4

1.6

3.7

6.6

10.4

【Step 3】 D etermine the type which canaccommodate the necessary displacement
perpendicular to the axis

Select the block number which can accommodate the【Step 1】Select the Bellows size (nominal diameter)

necessary displacement perpendicular to the axis andBased on the space in which the Bellows is attached,

select the Bellows type.

the Bellows size（nominal diameter）is selected. Here,For example, if the necessary displacement

we selected V20.

perpendicular to the axis is 5mm, the block number is 4

Catalog value of V20（1-block specification）

according to Table 1. So, the required type is V20–111–4.

Internal diameter = 20mm,

Regarding the Bellows length L, note that the length

Outside diameter = 40mm

excludes the length of fittings on both ends. In the

Expansion and contraction length = 10mm,case of V20–111–4, this length on both ends is 3mm, so

Expansion length = 15mm,

the overall length is 46mm.

Contraction length = 5mm【Step 2】Calculate‌the allowable displacement
perpendicular to the axis for each block number3-2）Displacement perpendicular to the axis
and displacement parallel with the axis

For the selected size
（nominal diameter）, the allowable

In the case where there is both displacement

displacement perpendicular to the axis is calculated

perpendicular to and parallel with the axis, as shownfor each block number.

in Section 2-2）, the calculation should be made withIn the case of 1 block:the length which becomes minimum under the effects

Expansion and contraction length = 10mm, Expansionof displacement parallel with the axis. The selection

11

Technical Papers

flow is the same as in Figure5.

applied, is 10 mm（15mm – 5mm = 10mm）.

【Step 1】Select the Bellows size（nominal diameter）

According to Equation（4）,Based on the space in which the Bellows is attached,
the Bellows size（nominal diameter）is selected. Here,
we selected V30.

In the same manner, increase the block number andCatalog value of V30（1-block specification）

calculate for each block number. Table2 shows theInternal diameter =30mm, Outside diameter =50mm

results.

Expansion and contraction length = 10mm, Expansion
length = 15mm, Contraction length = 5mm

Table2‌V30’s block number, displacement parallel with theaxis, displacement perpendicular to the axis

【Step 2】Calculate‌the allowable displacement

Block number

2

3

4

5

6

perpendicular to the axis for each block

L（mm）

20

30

40

50

60

Δ x（mm）±

5

5

5

5

5

For the selected size
（nominal diameter）, the allowable

Δ x（y）
（mm）±

5

10

15

20

25

displacement perpendicular to the axis against

Δ y（max）
（mm）

0.5

1.6

3.5

6.0

9.1

numberdisplacement parallel with the axis is calculated foreach block number. When the necessary displacement【Step3】‌Determine the type which canparallel with the axis is 10mm and the block number

accommodate the necessaryis 1, the converted displacement parallel with the axis

displacement perpendicular to the axis

In the case of 2 blocks:

Select the block number which can accommodate thenecessary displacement perpendicular to the axis andExpansion and contraction length = 20mm, Expansion

select the Bellows type.

length = 30 mm, Contraction length = 10mm

For example, if the necessary displacement

Bellows length L = 20mm; when there is only

perpendicular to the axis is 5mm, the block number isdisplacement parallel with the axis, then Δ x of up to

5 according to Table2. So, the required type is V30–±10mm is acceptable.

111–5. The Bellows length including the fitting length

When the necessary displacement parallel with theon both ends is 56mm.

axis of 10 mm is Δ x = ±5mm, Δ x（y）, the converted
value of allowable displacement parallel with the axis
when displacement perpendicular to the axis is

4. Design troubles and countermeasuresapplied, is 5mm（10mm – 5mm = 5mm）.

4-1）Investigation of Bellows’buckling

According to Equation（4）,One of the design problems of Bellows is buckling.
Bellows, like columns and springs, suffer buckling due
to compressive forces and lose straightness. Refer toIn the case of 3 blocks:

Figure2.

Expansion and contraction length = 30mm, Expansion

This buckling threshold value can be approximatedlength = 45mm, Contraction length = 15mm

by using the widely-used Euler’s formula:

Bellows length L = 30mm; when there is only…………（５）displacement parallel with the axis, Δ x of up to ±15mm
is acceptable.

where, Fcr：buckling load limit（N）

When the necessary displacement parallel with the

EI：Bellows’bending stiffness（N・mm２）

axis of 10mm is Δ x = ±5mm, Δ x（y）, the converted

L：Bellows’length

value of allowable displacement parallel with the axis
when displacement perpendicular to the axis is（mm）

Note : ‌Regarding EI, refer to Valqua Review Vol. 40,
1st issue. １）
12Summer 2018

Δ x（y）is 0. Therefore, at least 2 blocks are needed.

No.35

Design Guidelines and Troubles for DYNAMICBELLOWSTM and Countermeasures4-2）Bellows’buckling pressure4-3）Investigation of V Series’buckling

When Bellows are subjected to internal pressure, theNext, we examine the buckling of our standard

limit pressure which triggers buckling, or buckling

product V Series（Catalog No. PC08）. Refer to thepressure, can be calculated assuming that thrustcatalog and follow the steps.

develops in response to the pressure applied to the

In the catalog, one column shows the block number

effective area of the Bellows, and that the buckling

limitation. This shows the case in which the V Series’

load is equivalent to the thrust.

allowable pressure of 0.1 MPa is outside pressure andthe case in which the allowable pressure is the…………（６）

internal pressure. Among these block numbers, when
the allowable pressure is internal pressure, the block…………（７）
where, Pcr：Bellows’buckling pressure（MPa）
2

A：Bellows’effective area（mm ）number limitation is determined based on thebuckling pressure explained in Section 4-2）.
An example of calculating the buckling pressure isshown below.

d ：Bellows’inner diameter（mm）
D：Bellows’outside diameter（mm）
In this case, the longer the Bellows length L becomes,

Example 1. According to Equation（6）when the blocknumber is 4 which is V20’s block number limit,

the smaller the buckling pressure becomes, reducing

Summer 2018
No.35

the strength against buckling. Therefore, whencalculating, the maximum service length（expansion

In this case, the Bellows length L is calculated using

length）should be used.

the expansion length.

When the pressure significantly exceeds this limit

The details of EI are omitted here.

pressure, the Bellows will buckle and not expand or

When the block number is 4, L is 60mm（expansion

contract, which may result in deformation, a shorter

length 15mm × 4 blocks = 60mm）.

lifespan or early breakage.
Figure6 shows a case of breakage due to buckling.

Regarding the Bellows’effective area A, according toEquation（7）,Example 2. According to Equation（6）, when theblock number is 6 which is V100’s block number limit,‌In this case, when the block number is 6, theBellows length L is 90mm（15mm × 6 blocks =90mm）.
Regarding the Bellows’effective area A, according toEquation（7）,Figure6

13

Breakage due to buckling of Bellows

Technical Papers

Based on the results of the above calculation, the【Example 2】‌When a shaft is absent on the inside of the
Bellows

inner pressure of 0.1 MPa is not greater than thebuckling pressure, so buckling does not develop.

The structure becomes more complex and accurate

When the block number which can be used for the

positioning of the guide rod is needed.

necessary displacement parallel with the axis isselected and the selected block number is greaterthan the block number limitation, the guide shown in

Bush
Block number limitation

Guide rodthe catalog should be attached. This guide is shown in
Section 4-4）below.
4-4）Countermeasures to prevent buckling
When the block number exceeds the block number
limitation, a guide should be attached. An example ofthe structure is as follows.
【Example 1】‌When a shaft is present on the inside of
the Bellows
Figure7 is a frequently used structure.
Block number limitation

Figure9

Guide rods are placed on the surroundings

Shaft

location where the block number is equal to or lessthan the block number limitation.
When displacement perpendicular to the axis ispresent, guides cannot be placed. Therefore,

Summer 2018

As shown above, guides should be placed at every

Guidedisplacement perpendicular to the axis which is
Lubricant coating

Figure7

A guide inner surface is coated with lubricant

greater than the block number limitation is not
acceptable.
4-5）Block number limitation using outside pressure

Block number limitation

The V Series’block number limitation is shown whenShaft

the outside pressure is 0.1 MPa. In this case, we do
not calculate the buckling pressure; we calculate the
Bellows’horizontal deflection（refer to Figure3）toprevent the horizontal deflection from exceeding
1mm, using the equation:

PTFE bush

Figure8 A PTFE bush is attached to the guide inner surface

where, y（max）：Bellows’horizontal deflection（mm）
W ：Bellows’weight（kg）
L：Bellows’length（mm）

EI ：Bellows’bending stiffness（N・mm２）
In this equation, the effects of outside pressure are
ignored. When outside pressure is applied, the
14

No.35

Design Guidelines and Troubles for DYNAMICBELLOWSTM and Countermeasures

Bellows’deflection is considered to decrease.
Therefore, in this equation, we calculate values when

5. Conclusion

the Bellows inside/outside pressure is atmosphericThis article described the case of our standard

pressure.

DYNAMICBELLOWSTM V series（catalog No. PC08）
and examined the selection method when Bellows

Example 1）‌According to Equation（8）,when the blockabsorb displacement perpendicular to the axis, andnumber is 9 which is V20’s block number

design considerations regarding the block number

limit,

limitation.
As noted already, when Bellows with a length longer
than the block number limitation are used, there are‌In this case, the Bellows length L is calculated using

risks of deformation, a shorter lifespan, and breakage,

the expansion length.

so care is required.

The details of EI are omitted here.

We hope that this article will help prevent design

When the block number is 9, L is 135mm（15mm ×problems when selecting the V Series.

9 blocks = 135mm）. Also, the Bellows’weight W is
0.13kg.

6. References
１）Valqua Review Vol.39, 4th issue, Lecture on seals（23）

block number is 20 which is V210’s block

Vol.39, 5th issue, Lecture on seals（24）

number limit,

Vol.39, 6th issue, Lecture on seals（25）

Summer 2018

Example 2）‌According to Equation （8）, when theVol.39, 7th issue, Lecture on seals（26）
Vol.40, 1st issue, Lecture on seals（27）
Vol.40, 9th issue, Lecture on seals（28）
In this case, when the block number is 20, L is 300 mm

No.35（expansion length 15mm × 20 blocks = 300mm）andthe Bellows’weight W is 5.32kg.
4-6）‌Countermeasures to prevent horizontal
deflection
When the block number exceeds the block number
limitation, a guide should be attached. An example ofthe structure is similar to the example shown in
Section 4-4）.

Masafumi Ina
Sales Group
Technical Solution Division

15

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

Product Introductions

Substitute Sealants for Refractory
Ceramic Fiber
1. Introduction

has adopted inorganic fibers to replace RCF, as they
are soluble in living organisms, and has developed
products which are both safe and functional. Since

and used as substitutes for asbestos. However, there isthese fibers readily dissolve within the body whenconcern that some of them may be carcinogenic, andinhaled via the respiratory system, they are considered

so regulations have been introduced in each country.

to pose low risks to health and so are not subject to

In Japan, in November 2015, refractory ceramic fiber

legal regulations.

（RCF）was categorized as a Group-2 substance andTable1 shows products subject to RCF substitution.

specified chemical substance to be controlled underThis article introduces substitute products in terms of

the Ordinance on the Prevention of Hazards due tospiral wound gaskets, metal jacketed gaskets, rubber-Specified Chemical Substances（hereafter“Ordinance”）.

coated woven fabric gaskets, and gland packings.

The major regulatory items and management tasks
required in manufacturing are as follows.1）

Table1

Products subject to RCF substitution

Applicable product group

VALQUA part number

Spiral wound gasket

No.8590 series＜Major management tasks＞

Metal jacketed gasket

No. N510, N520, N530, N570, N580,
N6520, N6580① Placement of local ventilation

Rubber-coated woven
fabric gasket

No.P-N314

Textile productNo. P-101S, P-102SF, P-102S, P-105S
P-105SN, P-112S, P-112S-N

Gland packing

No. N340G-F, N340M-F② Nomination of an operational chief③ ‌Creation and preservation of notifications andoperation records④ Measurement of operational environment⑤ Medical examinations

2. Spiral wound gaskets

Although molded products in which binder is used to

Spiral wound gaskets are semi-metal gaskets designed

solidify RCF, and products in which RCF is sealed, arefor use under high temperature and high pressure,

not subject to the regulation, when such products are

and also have excellent sealing properties and heatcut or polished, RCF dust can be dispersed. Therefore,

resistance. Therefore, they are used in a wide range of

the Ordinance is applied to these products.

applications including general piping and devices, as

RCF is widely used as a refractory material and heatseals for steam and heat media. In a spiral woundinsulator, which can be used at high temperatures ofgasket, a V-shaped metal belt （hoop） and a soft

1,000ºC or higher, at various plants including steel, oil

sealing belt（filler）are wound together. Generally,

and chemical plants. Meanwhile, sealants have beenspiral wound gaskets, to which inner and outer metal

widely used in various products including gaskets andrings are attached, are used for various purposes

gland packings because of their excellent heat

depending on the conditions.

resistance. In line with legal regulations, VALQUA

Inorganic paper is one of the fillers used in spiral
24

Summer 2018

Various artificial mineral fibers have been developed

No.35

Substitute Sealants for Refractory Ceramic Fiberwound gaskets. In the paper-making process, organic/

properties of No. 8596V and No. 8596VL were

inorganic fibers, fillers, and rubber binders are mixedevaluated under the condition of heating the twoand then the mixture is made into paper. The

gaskets while connected to a flange, then cooling themmaximum service temperature is 500ºC. For

to room temperature. Table2 shows the results.

inorganic-paper fillers, RCF used to be used as a“Lined products”is a foamed-carbon filler in which

substitute inorganic fiber for asbestos.

inorganic-paper filler is placed at both ends of the

VALQUA developed inorganic-paper filler spiralfiller to prevent oxidation loss of the filler. No leakage

wound gaskets（No. 8590 series）containing biosoluble

occurs in RCF-substitutes; they were confirmed torock wool as a substitute fiber for RCF（Figure1）.

have adequate high-temperature sealing properties.

Biosoluble rock wool is a fiber which is not regulated

Table3 shows the results of evaluating steam resistance.

by the Ordinance; it is excluded from the carcinogenic

Generally, loss of fiber strength of biosoluble fibers is a

category by Note Q of Commission Directive 97/69/

concern when the fiber comes in contact with steam

EC“Carcinogenicity categorization and package

or water. To evaluate steam resistance, we evaluateddisplay regarding artificial amorphous fiber.”the sealing properties of the RCF-substitutes using

The performance of RCF-substitute products

nitrogen gas after steam exposure, and deterioration（hereafter“RCF-substitute（product）”）containing

was confirmed. The result shows that no leakage

biosoluble rock wool is shown below. The sealingdeveloped with the RCF-substitutes, and RCFsubstitutes have similar sealing properties to those of

Summer 2018

RCF-containing products.
Regarding design data including m/y values, there
were no changes following the change in fiber; theRCF-substitutes can be used in a similar manner as
conventional products containing RCF.
Table3 Comparison of steam resistance regarding No. 8596V

No.35
Figure1No. 8590 series（RCF-substitute products）

Table2 Comparison‌of high-temperature characteristics
between No. 8596V and No. 8596VL

Sealing-property evaluation, Inner pressure（MPa）
Steam exposure No. 8596V（RCF-containing product） No. 8596V（RCF-substitute）
time
2.0
4.0
2.0
4.0
Pre-exposure No leakage No leakage No leakage No leakage
1 weekNo leakage No leakage No leakage No leakage
3 weeks
No leakage No leakage No leakage No leakage
Note: Test conditions
Exposure fluid：30 K steam（230ºC, 3 MPa）
Tightening force：Bolt-fastening under a contact pressure equivalent to 70 MPa

Heating
temperature

3. Metal jacketed gaskets
Roomtemperature

Metal jacketed gaskets are semi-metal jacketed

Additional tightening

gaskets in which the outer side of felt（thick plate
made from inorganic materials）is covered with a thin

3

Leakage amount（Pa・m /s）
No.8596VL（RCF-substitutelined products）

metal plate. Since complex shapes and narrow sizes

500ºC

600ºC

they are used in towers and tanks as well as heat

No leakage

No leakage

No leakage

1

No leakage

No leakage

No leakage

2

No leakage

No leakage

No leakage

Specimen

No.8596V（RCF-substitute）

Heating temperature

400ºC

0

Cycle
numberNote: Test conditions
Internal pressure：4 MPa（400ºC and 500℃）, 1 MPa（600℃）
Tightening
force：Bolt-fastening under a contact pressure equivalent to 70 MPa‌25

can be manufactured using metal jacketed gaskets,
exchangers.
Metal jacketed gaskets are often used at temperaturesof 500ºC or higher. Since RCF has excellent heat
resistance, it is used as a core material for felt. Since theProduct Introductions

felt of a metal jacketed gasket is completely covered
with metal, there is minimal exposure risk, and so the

4. Woven fabric gaskets
Woven fabric gaskets are gaskets using fabric, ribbon,

for even safer use, we developed metal jacketed gaskets

or yarn. In these gaskets, RCF materials are used at（No. N510 and N520）which instead use inorganic fiber,

temperatures of 500ºC or higher. In some woven

which is not subject to the Ordinance（Figure2）.

fabric gaskets, special treatments are applied using

We compared the sealing properties between RCF-

rubber-soaked cloth. They are used at places wherecontaining products and RCF-substitute products at aleaking is relatively acceptable, such as in devices’heat cycle of 600ºC. In the comparison, gaskets were

manholes and the flanges of exhaust-gas ducts.

connected to a flange, several thermal cycles were

VALQUA started supplying gaskets that use

applied, and the room-temperature sealing properties

biosoluble fiber（BSF）instead of RCF. BSF remains inwere compared. Figure3 shows the results. According

the body for a shorter time than RCF and is notto the figure, even after the heating cycles, the RCF-

subject to the Ordinance.

substitute products appear to have equivalent or

When making RCF-substitute products, the wovensuperior sealing properties to those of RCF-containing

fabric, which the main material of BSF, is added withproducts.

a small amount of organic fiber and is soaked with

Regarding various design data, the same as in spiralrubber. Through this process, RCF-substitute has

wound gaskets, there were no changes in the metal

improved sealing properties.

jacketed gaskets. Therefore, RCF-substitutes can be

The sealing properties of RCF-containing products areused in a similar manner as RCF-containing products.

compared with those of RCF-substitute products at athermal cycle of 800ºC. Figure4 shows the results.
According to the figure, RCF-substitute products
appear to have equivalent or superior sealing

Summer 2018legal regulations do not apply to such gaskets. However,properties to those of RCF-containing products.
Regarding the design data of rubber-soaked woven
fabric gaskets, there were no changes. Therefore,rubber-soaked woven fabric gaskets can be used in asimilar manner as RCF-containing products. However,when only cloth and ribbon are used as textiles that
No. N510, N520, and others（RCF-substitute products）

Test Condition
Heat-cycle condition：600℃ × 15hours × 5cycles
Tightening force：‌Bolt fastening under a contactpressure equivalent to 70 MPa

No. N520（RCF-containing product）
No. N520（RCF-substitute product）

Beforeheating

Cycle number
Figure3 Comparison‌of high-temperature characteristics
regarding No. N520

are not soaked with rubber, care should be taken
No. N314（RCF-containing product） Test Condition
Heating condition：800℃ × 15 hours
No. P-N314（RCF-substitute product） Tightening force：‌Bolt fastening under a contactpressure equivalent to 24.5 MPa

Leakage amount（Pa・m3/s）

Leakage amount（Pa・m3/s）

Figure2

Internal pressure MPa

Figure4‌Comparison of high-temperature characteristics
between No. N314 and P-N314
26

No.35

Substitute Sealants for Refractory Ceramic Fiberregarding the maximum service temperature: that of
woven fabric using the conventional RCF is 1,260ºC,
whereas that of woven fabric using BSF is 1,000ºC.
The temperature difference is due to BSF’s inferior
heat resistance to RCF. One inorganic fiber that canbe used above 1,000ºC is alumina fiber, but it is very
expensive. Thus, challenges remain in this field.

5. Gland packings

Figure6

No. N340M-F（RCF-substitute product）

Gland packings are widely used as sealed packings for

Summer 2018

valves, rotary pumps, and various other devices. In a

On the other hand, BSF, which is used as an RCF-

gland packing, fibers are braided into a rope-like

substitute, is biosoluble. Therefore, under highshape. The cross section of a gland packing is square,temperature and dry conditions（dry heat）involving

and so the packing is highly versatile as a sealant andblast furnace gas or exhaust gas, BSF shows similar

is used for parts where some leakage is acceptableperformance as the conventional RCF-containing

but heat resistance is required. Examples include theproducts. However, durability in the presence of

coupling of exhaust-heat ducts of boilers and turbines

steam or hot water（wet heat）is unknown; care isand the fixing parts of manholes.

required.

Gland packings for these purposes are often used at

Although BSF will not break down immediately in thetemperatures above 400ºC, and so heat-resistant RCF

case of slight wetting, usage after adequate drying is

has been used for gland packings. However, RCF

recommended.

became subject to the Ordinance. Therefore, we used

Test Condition
Tightening contact pressure:
Mold cut-off
Fluid：Compressed air
Heating condition：15 hours × 500℃

BSF, which is not subject to the regulation, instead of
RCF, and started supplying the RCF-substitute glandpacking（Figures5 and 6）.
We compared the high-temperature characteristics of
No. N340M（RCF-containing product）with those of
N340M-F（RCF-substitute product）at 500ºC. Figure7
shows the results. According to the figure, No.
N340M-F（RCF-substitute product）appears to haveequivalent or superior sealing properties to those of
No. N340M（RCF-containing product）.

Leakage amount（Pa・m3/s）

No.35

No. N340M（RCF-containing product）
No. P-N340M-F（RCF-substitute product）

Loading internal pressure（MPa）

Figure7 Comparison of sealing properties at high temperatures

6. Conclusion
Sealants consist of combined materials with varying
characteristics including heat resistance, chemical
resistance, and high intensity to withstand various
challenging conditions. However, international
Figure527

No. N340G-F（RCF-substitute product）

regulations have been tightened to reduce theProduct Introductions

environmental burden and negative impacts on thehuman body, placing increasing restrictions on usable

7. Reference１）‌Japan High Temperature Insulation Wool Association,materials.
As a seal manufacturer, VALQUA will continue toHandling of ceramic-fiber products, revised edition

reduce the environmental burden and develop（January 2016）.

products that do not negatively affect the human
body, thus contributing to customers’safety.

Masato Hamade
Corporate Research andDevelopment Group
Product Development DivisionⅠ

Summer 2018
No.35

28

Sheet Gaskets for High-Temperature Use
VALQUA HEAT RESIST SHEET™ No. HRS
1. Introduction

Summer 2018

Under high-temperature conditions in petroleum refining

2-1）Compositionand petrochemistry industries, spiral wound gaskets,

No. HRS is a white sheet consisting of inorganic

metal jacketed gaskets, ring joint gaskets, and rubber-materials. Like foamed carbon sheet No. VF-35E, No.

coated woven fabric gaskets are used. Appropriate

HRS is made by fixing a sheet material on both surfaces

gaskets are selected depending on the pressure classes.

of a stainless-steel thin plate（thickness：0.05 mm）.

Among such gaskets, rubber-coated woven fabricFigure1 is a photograph of the exterior and Figure2

gaskets are used under low-pressure conditions and areshows the composition.

not dense, so they cannot provide adequate sealing2-2）Characteristics

properties. Furthermore, due to material deterioration,① Compared with the conventional rubber-coatedthey carry risks regarding medium- to long-term sealing

woven fabric gasket, No. HRS offers significantly

properties. In addition, refractory ceramic fiber（RCF）,

improved sealing properties, effectively reducing

which is a constituent material of the rubber-coatedthe discharge of environmental contaminants

woven fabric gasket, was categorized as a Group-2

No.35

2. Composition and characteristics

including NOx and SOx in combustion gas.

substance and specified chemical substance to be② N o. HRS minimizes the content of organic

controlled under the Ordinance on the Prevention of

constituents including rubber binder. In addition,

Hazards Due to Specified Chemical Substances in

No. HRS contains inorganic fiber which has

November 2015, and so we could not source RCF fromexcellent heat resistance, and so can be used at

the material manufacturers. Although RCF was replaced

temperatures of up to 1,200ºC.

with biosoluble fiber（BSF）, the heat resistance of BSF③ No. HRS has less sticking to flanges than rubber-is inferior to that of RCF, and it is difficult to use BSF

coated woven fabric gaskets, so cleaning is easier.

above 1,000ºC.
To solve these challenges, VALQUA significantly
improved the sealing properties compared with those of
the conventional rubber-coated woven fabric gasket todevelop VALQUA HEAT RESIST SHEET™ No. HRS, a
sheet gasket which can be used at temperatures up to
1,200ºC. No. HRS solves the problems of gaskets used athigh temperature and low pressure. This article
introduces the characteristics of VALQUA HEATRESIST SHEET™.
Figure1 Exterior of VALQUA HEAT RESIST SHEET™ No. HRS
29

Product Introductions

White inorganic sheet4-2）Service temperature range
The service temperature ranges from −200 to 1,200ºC.

Stainless-steel thin plate

No. HRS is designed for use under low-pressure
conditions including exhaust ducts. Therefore, metal
gaskets and semi-metal gaskets are recommended foruse under high-pressure conditions of 1 MPa or higher.
4-3）Recommended‌tightening contact pressure andmaximum allowable tightening contact pressure
Table2 shows recommended tightening contact pressures.

Figure2

Table2

Product composition

3. Intended use
No. HRS is suitable as a sealant for places such asdevices’manholes and exhaust ducts having thefollowing characteristics：1）Although the inside fluid is
at low pressure, the flange’s strength is weak, and 2）

Recommended tightening contact pressures
Fluid

Recommended tightening
contact pressure（MPa）

Liquid

20

Gas

20

Note：‌The recommended tightening contact pressure is that which isnecessary under general conditions. It is set without taking
the fluid pressure into account. It is the contact pressure
regarding the gasket's contact area.

tightening force cannot be applied. Also, No. HRS can beused as a sealant for oil burners, high-temperature

5. Evaluation of characteristics

wafters, and the access doors of heat-recovery lines.

5-1）Sealing properties at room temperature

Although No. HRS has much better sealing properties

Figure3 shows the results of evaluating the sealing

than the conventional rubber-coated woven fabricproperties at room temperature. The leakage volume isgasket, it suffers greater leakage volume than sheet

1/100 or less compared with that of the conventional

gaskets including joint sheets, so care is required.

rubber-coated woven fabric gasket, showing that No.
HRS has significantly improved sealing properties. In
addition, its leakage volume is small even at tightening

4. Product specifications

contact pressures between 10 and 20 MPa. Therefore,

4-1）Standard size

No. HRS provides good sealing even at locations where a

Table1 shows the standard sizes of No. HRS. Two sizes,

large tightening force cannot be applied due to the

1.5 mm and 3.0 mm in thickness, are available; theflange’s strength.

maximum outer diameter is 900 mm. Since No. HRS is a

Table1Thickness
1.5

3.0

Standard size（Unit：mm）

Maximum outer diameter
900

No. HRS Woven fabric gasket

Specimen size：JIS10K-25A t3
Internal pressure：0.2 MPa（helium）

Leakage volume（cc/min）sheet gasket, it can be processed into various shapes.

Gasket’s contact pressure（MPa）

Figure3

Sealing properties at room temperature30

Summer 2018

Although the inside fluid is at low pressure, a large

No.35

Sheet Gaskets for High-Temperature Use VALQUA HEAT RESIST SHEET™ No. HRS

5-2）Heat-cycle sealing properties
The sealing properties of No. HRS were evaluated asfollows: 1）No. HRS was heated while connected to aflange. 2）The heating/cooling process was repeatedly
applied to No. HRS. 3）After cooling, the sealing
properties at room temperature were evaluated. Figure4
shows the results. No. HRS has a smaller leakage volume
than the conventional rubber-coated woven fabric gasket
even after heating, and maintains strong sealing
properties even after repeated cycles.

No. HRS
Woven fabric gasket

Specimen size：JIS10K-25A t3
Heating cycle：800℃ × 15 hours × 5 cycles
Internal pressure：0.2 MPa（nitrogen）
Tightening contact pressure：24.5 MPa
Test method for sealing property：Submersion method

Figure5

Dovetail-groove processing

We evaluated the sealing properties of gaskets with orwithout dovetail grooves. Figure6 shows the results.

Summer 2018

Leakage volume（cc/min）

Joining ① is without paste application. In Joining ② ,gasket paste No. 6M is applied to the surfaces of thejoining ends. The difference in leakage volume between
no joining and joining ① is insignificant; the two
conditions have similar sealing properties. For safer
usage, we recommend applying paste No. 6M to the
Beforeheating

1st
cycle

2nd
cycle

3rd
cycle

4th
cycle

surfaces of joining ends when joining products are used.
No joining
Joining ①（Heating-cycle conditions）

Room
temperature

Figure4

Leakage volume（cc/min）

No.35

Joining ②

Joining ① : 2 joined points
Joining ② : 2 joined points+ paste No. 6M was applied to the surface of the joined end.
Specimen size：JIS10K-50A t3
Internal pressure：0.2 MPa（helium）

Heat-cycle sealing properties

5-3）‌Sealing properties of joining products atroom temperature

Contact pressure（MPa）

Figure6 Sealing properties of joining products at room temperature

The maximum outer diameter of No. HRS is 900 mm.

5-4）Heat resistance

However, joining through dovetail-groove processing

To evaluate heat resistance, we evaluated the shape-（Figure5）enables No. HRS to handle products withretention characteristics after heating. Figure7 shows

larger diameters. In that case, joining is only conducted

the gaskets’appearance after heating in air at 1,000ºC

at the construction site.

and 1,200ºC. Even after heating, No. HRS had no
deformation or powdering; it kept its original shape.

31

Product Introductions

Therefore, there is little risk in high-temperature usage

5-6）Resistance to crushingof, for example, gasket breakage due to internal

When an excessive tightening force is applied to gaskets,pressure.

they can break. In an experiment, No. HRS was
subjected to a contact pressure of 100 MPa, as shown in

Heating time：24 hours
Atmosphere：Air
Test-use dimensions：45 mm×15 mm×t3.0

Figure9. Even after this tightening contact pressure wasapplied, the gaskets did not suffer compression fracture.
Test-use dimensions：φ100 × φ64
Loaded contact pressure：100 MPa
Crushing condition：Cracks developed

Before heating
Figure7

Results of evaluating shape retention after heating

In high-temperature environments, gaskets strongly
stick to flanges, and so time and labor are required forremoval. Figure8 shows the sticking tendency to flanges

Figure9‌Appearance of gasket after application of contactpressure of 100 MPa

after repeated heating cycles. In No. HRS, the amount ofrubber binder is reduced to the minimum, and verysmooth inorganic filler is used. Therefore, No. HRS sticks

6. Conclusion

to flanges much less than the conventional rubber-This article introduced VALQUA HEAT RESIST

coated woven fabric gasket, which facilitates flange

SHEET™ No. HRS. No. HRS has significantly better

cleaning and reduces man-hours in construction.

sealing properties and heat resistance than conventional

Heating cycle：800℃ × 15 hours × 5 cycles
Flange material：SUS316L

rubber-coated woven fabric gaskets, which have beenused for high-temperature and low-pressure applications.
This product ensures long-term safety. Some customers
have already conducted actual evaluations, and somehave already introduced No. HRS. Environmental
regulations will get stricter in future. We hope you will
use No. HRS gaskets which comply with environmental
regulations.

Satomi Takahashi
Figure8

Sticking to flanges

Summer 20185-5）Sticking tendency

Corporate Research andDevelopment Group
Product Development DivisionⅠ
32

No.35

Recent Technology News Back Issues
No.34 Winter 2018
【Customer Solution Feature】● Greetings

President & CEO

Toshikazu Takisawa● Introduction to Valqua Technology News No. 34 Winter 2018	

● Commentary

Senior Executive Officer

Director of Corporate Research and Development GroupASME PVP 2016-Awarded Paper

Ｈ＆Ｓ BUSINESS GROUP

Mutsuo Aoki

Akira Muramatsu● Technical Papers

Evaluation of the Mechanical Behaviors of Pipe Flange Connections with PTFE Gaskets Subjected to Bending Moment
	
Corporate Research and Development Group Product Development Division Ⅰ Koji Sato		
University of Hiroshima Toshiyuki Sawa
Mitsubishi Chemical Corporation Riichi Morimoto		Numazu College Takashi Kobayashi		Corporate Research and Development Group Product Development Division Ⅰ Yuta Motono
		
Performance Evaluation of Improved EPDM Material under High-temperature Environments
Corporate Research and Development Group Product Development Division Ⅰ Ken Suzuki
CHUBU Electric Power Co.,Inc. Shinichi Matsuda
		
CHUBU Electric Power Co.,Inc. Takuya Sugimura		Guidelines on Gasket Selection, Selection Troubles, and Countermeasures
Sales Group Technical Solution Division Asuka Matsushita● Contribution

Considerations for Tool Selection and Installation of Fastening Bolts for Flanges with Large Nominal Diameters
TORQUE SYSTEM Co.,Ltd. Managing Director Shinichi Kitahara● Business Introduction

H&S Demonstration Car● Product introduction

Improved Seal Paste
Corporate Research and Development Group

Ｈ＆Ｓ Business Group

Hajime Nonogaki

Product Development Division Ⅰ

Masato Hamade

Summer 2018

Multi-Purpose Gland Packing for Chemical Applications
Corporate Research and Development Group

Product Development Division Ⅰ

Corporate Research and Development Group

Product Development Division Ⅰ

Syuuzi Sugawa
Masato Hamade●Recent Technology News Back Issues

No.33 Summer 2017

No.35 【Customer Solutions Special】● Greetings	● Technical Papers

Senior Excutive Officer

Director of Corporate Research and Development Group

Mutsuo Aoki

Unsuitable Usage Conditions of Gaskets and CountermeasuresTechnical Solution Division Toshihiko Enishi
Flange Connection with Metallic Flat Gasket
Corporate Research and Development Group Development Division Kouji Satou
SHINKO PLANTECH CO., LTD. Yasuharu Kondou
Professor Emeritus at the University of Hiroshima Toshiyuki Sawa
Corporate Research and Development Group Satomi Takahashi
Sales Group

Evaluation of Basic Sealing Properties of the Pipe


	
	
	

Troubles While Mounting Gaskets and Countermeasures
Sales Group Technical Solution Division Satoshi Akiyama
	
An Introduction and How to Use Seal Quick SearcherTM（SQS） –Elastomer Version–	
Corporate Research and Development Group Development Division Akira Ueda
Seal Training Center (STC) –	● ContributionManagement of Tightening of Flanged Fasteners at Plants
Mitsubishi Chemical Corporation Mizushima Plant Mechanical Group 2
Maintenance and Engineering Department Riichi Morimoto●Recent Technology News Back Issues
33Interactive Training for Sealing Operation
Ｈ＆Ｓ BUSINESS GROUP Akira Muramatsu

No.32 Spring 2017
【The 90th Anniversary Special Edition】●Greeting	President & CEO

Toshikazu Takisawa●Greetings upon the Publication of the 90th Anniversary Special Issue	
Senior Excutive Officer Director of Corporate Research and Development Group Mutsuo Aoki
●Upon the Publication of the 90th Anniversary Special Issue

Editorial board of the 90th anniversary special issue of Valqua Technology News

●Transition of Valqua’s technologies and customer value

Looking back at the history of Valqua Technology News and Valqua Review
Senior Fellow Takahito Nishida●Contribution Congratulations on the 90th Anniversary Special Issue of Valqua’s Establishment
Professor Emeritus at the University of Hiroshima●Contribution Evolving Gasketing and Sealing Technologies
Professor at Mechanical Engineering, National Institute of Technology, Numazu College

Toshiyuki Sawa

Takashi Kobayashi●Contribution Congratulations on the 90th Anniversary Year of the Founding

NIPPON VALQUA INDUSTRIES, LTD.

former Managing Director (Technical Manager)

Takao Iwane●Contribution Congratulations on the Publication of the 90th Anniversary Special Issue of Valqua Technology NewsNIPPON VALQUA INDUSTRIES, LTD.

former Managing Director (Technical ･ Business development)●Contribution Memories of My Tenure as CTOYoshiaki Mori

Hiroyuki Kuroda

NIPPON VALQUA INDUSTRIES, LTD. former CTO●Technical Papers Types and Application of Filler-added PTFE Materials

Corporate Research and Development Group

Development DivisionHigh Performance Plastics Development Division

Youichiro Wada

●Technical Papers Accuracy and Mold Direction of PTFE Products

Corporate Research and Development Group Development Division High Performance Plastics Development Division
Technical Service Section No.3 Shigeko Kawai
Corporate Research and Development Group Development Division High Performance Plastics Development Division
Technical Service Section No.3 Nobuyuki Ota●Technical Papers Introduction and Utilization of Seal Quick SearcherTM（SQS）– Gasket Version –

Sales Group

Technical Solution Division

Toshihiko Enishi●Technical Papers Causes of and Countermeasures for Allophone Trouble in a Piston Seal System for Cylinders
Corporate Research and Development Group

Development Division●Technical Papers Sticking Troubles of O-Rings and CountermeasuresCorporate Research and Development Group

Development Division

Kenichi Takahashi
Masanori Okazaki●Technical Papers Evaluation of the Bolted Flange Connection with PTFE-blended Gasket under High-temperature and Long-term condition

Corporate Research and Development Group

Summer 2018


Development Division

Kouji Satou●VALQUA’s Technical History●Recent Technology News Back Issues

From Nippon Valqua Industries, Ltd. to“VALQUA, LTD.”We will continue to globalize by engaging not only in manufacturing but also in value
creation in products, events and human relationships. We will transform into“a value-creation company through products, events and humans”.
To reflect this determination, we will change our company name from Nippon Valqua
Industries, Ltd. to the new company name“VALQUA, LTD.”as of October 1, 2018.

34

No.35

Earth-friendly, Human-friendly Manufacturing

New Gaskets andGasketing Technology
Recent environmental regulations have led to a majortransformation in the different types of gaskets and theirmaterials. Likewise, we are also seeing major changes
in the design standards for bolted flange connections.
In response to this technical situation, JISB0116“Glossary of Terms for Packings and Gaskets” wascompletely revised for the first time in 37 years.
The recently published “New Gaskets and GasketingTechnology” is the first handbook that both covers thetechnical background leading up to this JIS terminology
standards revision and explains the technical basics ofgaskets and bolted flange connections in an easy tounderstand manner. As such, we feel it will serve as areference for many of those involved in gaskets.
Author: NIPPON VALQUA INDUSTRIES, LTD.
Takahito Nishida, Senior Fellow

ThinkPark Tower 24F
2-1-1 Osaki, Shinagawa-ku, Tokyo 141-6024, Japan
Contact: NIPPON VALQUA INDUSTRIES, LTD.
Email: sr@valqua.co.jp
TEL：(81)3-5434-7370
FAX：(81)3-5436-0560

VALQUA's Sales Network■JAPANNIPPON VALQUA INDUSTRIES, LTD【Main Number】 TEL : (81)3‑5434‑7370 FAX : (81)3‑5436‑0560【Sales Group】
TEL : (81)3‑5434‑7379 FAX : (81)3‑5436‑0571

No.35 Summer 2018

VALQUA SES CO., LTD.
TEL : (81)436‑20‑8511 FAX : (81)436‑20‑8515
VALQUA TECHNO, LTD.
TEL : (81)3‑5434‑7520 FAX : (81)3‑5435‑0264■CHINA

VALQUA(SHANGHAI) TRADINGCO., LTD.
TEL : (86)21‑5308‑2468 FAX : (86)21‑5308‑2478
SHANGHAI VALQUA FLUOROCARBON PRODUCTS CO., LTD.
【Head Oﬃce】
TEL : (86)21‑5774‑1130 FAX : (86)21‑5774‑1244【Jingansi Oﬃce】 TEL : (86)21‑3253‑5588 FAX : (86)21‑3253‑5568■KOREA

VALQUA KOREA CO., LTD.
【Head Oﬃce】
TEL : (82)2‑786‑6718 FAX : (82)2‑786‑6719【Ulsan Oﬃce】
TEL : (82)52‑227‑6717 FAX : (82)52‑227‑6719■TAIWANTAIWAN VALQUA ENGINEERING INTERNATIONAL, LTD.
【Head Oﬃce】
TEL : (886)7‑556‑6644 FAX : (886)7‑556‑9907【Hsinchu Oﬃce】 TEL : (886)3‑572‑0467 FAX : (886)3‑573‑7232【Luzhu Oﬃce】 TEL : (886)7‑696‑2400 FAX : (886)7‑696‑7100■SINGAPOREVALQUA INDUSTRIES SINGAPORE PTE.LTD.
TEL : (65)6352‑2650
FAX : (65)6352‑2653■THAILANDVALQUA INDUSTRIES(THAILAND), LTD.
【Head Oﬃce】
TEL : (66)2‑324‑0400 FAX : (66)2‑324‑0787【Rayong Branch】 TEL : (66)38‑026‑136 FAX : (66)38‑026‑137■USA

VALQUA AMERICA, INC.
TEL : (1)408‑986‑1425

FAX : (1)408‑986‑1426

VALQUA NGC, INC.
TEL : (1)713‑691‑1193

FAX : (1)713‑691‑4407■VIETNAM

VALQUA VIETNAM CO., LTD.
【Head Oﬃce】
TEL : (84)220‑357‑0078 FAX : (84)220‑357‑0079【Hanoi Branch】 TEL : (84)24‑3222‑2213 FAX : (84)24‑3222‑2216*The VALQUA registered trademark stands for VALUE and QUALITY.
*The contents of this journal also appear on our home page. *Unauthorized reprinting/reproduction is prohibited.