Winter 2018No.34
http://www.valqua.co.jp【Customer Solution Feature】● Greetings・
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President & CEO

Toshikazu Takisawa● Introduction to Valqua Technology News No. 34 Winter 2018・
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Senior Excutive Officer Director of Corporate Research andDevelopment Group Mutsuo Aoki

● Commentary
ASME PVP 2016-Awarded Paper ・
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Akira Muramatsu

Ｈ＆Ｓ BUSINESS GROUP● Technical Papers
Evaluation of the Mechanical Behaviors of Pipe Flange
Connections with PTFE Gaskets Subjected to Bending Moment ・・・7
Corporate Research and Development Group ProductDevelopment Division Ⅰ Koji Sato
University of Hiroshima Toshiyuki Sawa
Mitsubishi Chemical Corporation Riichi Morimoto
Numazu College Takashi Kobayashi
Corporate Research and Development Group ProductDevelopment Division Ⅰ Yuta Motono● Technical Papers

Performance Evaluation of Improved EPDM Material
under High-temperature Environments・
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・15
Corporate Research and Development Group ProductDevelopment Division Ⅰ Ken Suzuki
CHUBU Electric Power Co.,Inc. Shinichi Matsuda
CHUBU Electric Power Co.,Inc. Takuya Sugimura● Technical Papers

Guidelines on Gasket Selection, Selection Troubles, and Countermeasures・・・21
Sales Group Technical Solution Division Asuka Matsushita● Contribution

Considerations for Tool Selection and Installation of Fastening
Bolts for Flanges with Large Nominal Diameters・
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・27
TORQUE SYSTEM Co.,Ltd. Managing Director Shinichi Kitahara● Business Introduction

H&S Demonstration Car・
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・32
Hajime Nonogaki

Ｈ＆Ｓ Business Group● Product introduction

Improved Seal Paste・
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・35
Corporate Research and Development Group
Development Division Ⅰ Masato Hamade

Product● Product introduction

Multi-Purpose Gland Packing for Chemical Applications・・38
Corporate Research and Development Group
Development Division Ⅰ Syuuzi Sugawa
Corporate Research and Development Group
Development Division Ⅰ Masato Hamade

Product
Product● Recent Technology News Back Issues・
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・44

Greetings
Toshikazu Takisawa
President & CEONIPPON VALQUA INDUSTRIES, LTD.

I wish everyone much happiness in the new year, 2018.
First of all, we sincerely thank our valued readers for your continuinginterest in our magazine.
Thanks to your support, Valqua Technology News, our technical journal, recently celebrated its 60th
anniversary.
On this occasion, we greatly thank everyone, including all our consumers and readers who havesupported us for a long time.
We expanded our unique technological legacy to develop“seal engineering service.”Based on this, wewill strive harder to create innovative technology with novel values, and to contribute to achieving asustainable society. We will also do our best to make Valqua Technology News easier to understand

Winter 2018

and use for our readers.
In reviewing the Japanese economy in 2017, company earnings appeared to improve, reflecting a
recovery in exports, led mainly by the IT industry, and brisk personal consumption.
Overseas, the following trends were observed: 1）The U.S. economy showed a mild recovery trend,

No.34

supported by capital investment which was primarily driven by domestic demand, and 2）Indeveloping countries, economic growth slowed down due to structural reform of the Chinese economy,
the strained geopolitical situation, and other factors.
Meanwhile, the Japanese manufacturing industry suffered scandals including fraudulent quality
inspection systems, which form the foundation of manufacturing. Such scandals highlighted theimportance of corporate social responsibility and risk management. On the other hand, various
industries actively utilized new technologies including AI and IoT in 2017.
Under such conditions, the Valqua Group completed its 7th medium-term management plan New
Valqua Stage Seven（NV・S7）. At the same time, Valqua is promoting technological development, which
is based on seal engineering service, for the next stage, NV・S8. Through the technologicaldevelopment, we will expand our business to create novel values in the global market.
We would greatly appreciate your continued guidance and encouragement, and we wish everyone
many more successful years.
1Introduction to Valqua Technology NewsNo. 34 Winter 2018

Let us begin by wishing everyone a Happy New Year, and sincerely thanking our valued readers foryour continuing interest in our magazine.
The year 2017 witnessed many environmental changes. IoT and AI technologies have enteredpractical use such as for automated driving and the home-connected Internet. The conventional
market is undergoing a complete structural change and new market opportunities are emerging. On
the other hand, due to increased global awareness of environmental issues and accelerating
technological development in both the public and private sector, the range of conventional products istransforming so quickly and drastically that the traditional approach to product lifestyle cannot cope.
For example, the auto industry is experiencing dramatic changes in product lineups, and suchexamine how to respond to such changes.
Amid this environment, Valqua, a leading seal engineering company with a history of 90 years, will

Winter 2018transformations are emerging in various markets. Therefore, as a company, we must seriously

continue to contribute to social sustainable development through our unique and creative technologies
based on our corporate philosophy of“The Valqua Way.”In order to develop unique and creativetechnologies, we are determined to expand our role as a provider which takes customers’viewpoints
into account to provide new solutions in various fields.
This issue features technical papers and businesses which contribute to industrial safety and security
under various conditions and special environments. These include a paper which was awarded ASMEPVP Award（best paper award）from the Computer Technology & Bolted Joints TechnicalCommittee of ASME PVP; a paper on the behavior of flange connections at the time of anearthquake; a paper on countermeasures against severe accidents; and a paper on countermeasuresagainst seal troubles. Regarding our hard & seal engineering service（H&S）business, this issue
introduces a contributed article and Valqua’s approaches. All the articles in this issue featuretechnical information which is unique to Valqua. We hope you will find it useful.
We will continue to provide technical information which meets the needs of the times, and hope thatyou will continue to use Valqua products.
Senior Excutive Officer

Director of Corporate Research and Development Group

Mutsuo Aoki
2

No.34

ASME PVP 2016-Awarded Paper

1. Introduction

ceremony; Figure2 shows the certificate ofcommendation given at the ceremony.

In 2016, we contributed and presented the paper

This article introduces the paper’s contents and the“FEM Stress Analysis and the Sealing Performance

future prospects for basic research regarding thisEvaluation of Bolted Pipe Flange Connections withtheme.

Large Nominal Diameter Subjected to Internal
Pressure,”which examines the mechanical behavior offlange connections with large nominal diameter, at thePressure Vessels & Piping Conference（PVP）. PVP is

Winter 2018a technical divisionof the American Society of
Mechanical Engineers（ASME）.
ASME’s PVP, which consists of 12 committees, holds a
professional meeting annually, at which various papers
are presented. Among the papers presented,
approximately 10 are nominated and receive awards of

No.34

excellence. Our paper received an award from theComputer Technology & Bolted Joints TechnicalCommittee, one of the 12 committees.
Figure1 shows a picture of the commendation

Figure2 ＡＳＭＥＰＶＰＡＷＲＤ

2. Approaches to basic research
Seal engineering is our core technology. Using thistechnology, we are developing and expanding ourservices associated with flange working methods tosuit the needs of customers’ plant operation.
The tightening force of a bolt varies depending on thesize of the flange. Therefore, different tools should be used
A Valqua staff member receives a commendation from Mr.
Trevor G. Seipp, Honors and Awards Chair（left）.
Figure1 Commendation ceremony
3

to fasten bolts depending on the flange size. We propose
optimal tools that suit the customer’s usage environment,
and such proposal work is one of our services.

Commentary

These services have been gradually recognized in themarket, and so we began to receive inquiries not only

3. ASME PVP 2016-awarded paper
In this study, stress analyses using the finite element

including optimal fastening procedures, regarding themethod（FEM）were conducted to propose a method

fastening of flanges with large nominal diameters.

to evaluate the sealing performance and develop a

However, more bolts are used in fastening flanges withbolt-tightening method.

large nominal diameters, and under such conditions, a

When gaskets are compressed, internal stressmarked phenomenon unique to flange tightening,develops. Since the sealing performance of a flange

called elastic interaction, occurs. In elastic interaction,connection is considered to be determined by thisaxial bolt force, which secures the sealing performanceinternal stress, stress analyses using the finite elementof the gasket, is greatly affected by the tightening

method（FEM）were conducted to calculate the flange

force of the neighboring bolts. Therefore, more leakage

connection’s contact pressure when pressure is applied

troubles are known to develop regardless of theto the internal side of the flange connection throughgasket’s performance. For this reason, basic research is

fluid after the gaskets are compressed using bolts. In

essential in order to propose optimal flange working

the analyses, spiral-wound gaskets containing foamed

methods. Based on such research, the mechanicalcarbon filler（No. 6596V）and joint sheet（No. 6500）,

behavior associated with flange connections will be

and the analysis code ABAQUS were used.

elucidated and bolt tightening methods will be

Figure4 is a model of a flange connection under inner

established.

pressure（P）.

Therefore, we built 24-inch flange connections as

Figure5 shows an FEM model of element

shown in Figure 3. The 24-inch flange connection is thedecomposition. In the finite element analysis, we took

largest of the standard flanges. We then conducted

the symmetrical properties into account to divide thestress analyses using the finite element methodmodel in half in the axial direction and in 1-bolt length（FEM）to predict the flange’s seal performance. As ain the circumferential direction.

result, we established the method and published aNo.34

paper on it.
Stress analysis using the finite element method（FEM）involves calculating the deformation behaviorof a structure based on its mechanical characteristics
in order to predict changes.

Figure3

24-inch flange connection

Winter 2018about tool selection but also flange working methods,

Figure4

FEM model of a flange connection
4

ASME PVP 2016-Awarded Paper

Figure5 FEM model

Figure7 O utline illustration of the test equipment
stipulated by JIS B 2490

The basic leakage amount of the gasket was calculated
according to JIS B 2490.
Figure7 illustrates an outline of the test equipment
stipulated by JIS B 2490.

Winter 2018

Figure8 shows the results from a test conductedaccording to JIS B 2490; the bold line indicates thebasic leakage amount of the gasket, which was
calculated as the leakage amount plotted against thegasket’s contact pressure on unloading.
This basic leakage amount of the gasket was

No.34

Figure6 contact gasket stress distribution of the spiralwound gasket in the radial direction

compared with the leakage amount obtained by anexperiment, in which the leakage amount of the flange

Figure6 shows the contact gasket stress distribution ofconnection was calculated based on the averagea spiral-wound gasket in the radial direction. The

contact-pressure pattern of the gasket shown inhorizontal axis indicates dimensionless numbers. The

Figure6.

number was calculated by dividing the length between
the center and the pressure point in the radial
direction by the gasket’s internal diameter. On theassumption that two flanges were tightened in parallelwith each other, this study was conducted under thecondition that the contact gasket stress does notchange much in the circumferential direction, but onlyin the radial direction.
This figure indicates the trend that the larger theflange, the greater the contact pressure on the side of
the gasket’s outside diameter. This trend indicates
that, after bolt tightening, the application of pressure
through fluid generates rotation which deforms flanges
in the circumferential direction.
5

Figure8 Measurements of basic leakage amount of spiral-wound gaskets

Commentary

customers, and then propose the optimal working
methods.
Receiving an award for this paper showed that ourstudy is highly evaluated in the United States, where
sealing technology is actively studied. This highevaluation not only raises the brand profile of Valqua
but also verifies our evaluation methods and working
methods regarding flange connections. We received an
inquiry regarding tightening methods for flanges withlarge nominal diameters from a major U.S. oil company
soon after presenting this paper, indicating strong
Figure9 C omparison of the results from the experimentwith the analysis resultsinterest in this theme. This quick reaction indicatesthat even major oil companies have problems
regarding tightening methods for flanges with large

with the analysis results.

nominal diameters and wish to collaborate with

The red line represents the spiral-wound gasket andcompanies which possess advanced sealing technology.

the blue line represents the joint sheet; both gaskets

Cooperation with major oil companies might be

had less leakage when the gaskets’contact pressure

achieved by strengthening Valqua’s technologicalincreased. The experimental and analysis results

foundation using the results of this study.

matched closely, indicating the validity of theanalytical method.
With this analytical method, it is possible to predict the

5. Conclusion

leakage amount of a flange connection. Also, theIn this study, an ideal flange connection was

results indicate that setting a higher initial tightening

established as an ideal model, assuming the flange andforce of the bolts is effective for reducing the leakage

bolts had no scratches and the gasket was tightened

amount.

uniformly.
However, in actual working conditions, we cannot

4. Future prospects

fasten such ideal flanges; for example, gaskets arecompressed unevenly. In future, we aim to determine

Currently, we are studying how to apply these results

the effects of such uneven fastening on the sealing

to our proposal services regarding flange working

performance of flange connections, and to establish

methods, and are now introducing these services. In

solutions to on-site problems.

the long run, we believe that application of the results

In addition, since the thermal burden and externalof this basic research will allow us to evaluate andforce can affect actual piping, we intend to take theseanalyze working methods, which are difficult foreffects into account in further studies.

Akira Muramatsu
Ｈ＆Ｓ BUSINESS GROUP
6

Winter 2018

Figure9 compares the results from the experimentNo.34

Evaluation of the Mechanical Behaviors
of Pipe Flange Connections with PTFE
Gaskets Subjected to Bending Moment
1. Introduction

behaviors of pipe flange connections with PTFE

The pipe flange connection with gasket is widely usedgasket are not well defined: gasket contact stressat petroleum-refining, chemical, and power-generating

distribution, sealing performance, changes in hub

plants. In Japan, asbestos gaskets were widely usedstress and axial bolt force, and other behaviors.

and intensively researched, since those were low-cost

The authors previously studied the abovementioned

and offered excellent heat resistance, sealingmechanical behaviors of pipe flange connections withperformance, durability, and ease of handling. １）- ３）

PTFE gasket at room temperature and high４）

However, a regulation

Winter 2018
No.34

connecting parts.5） However, the following mechanicalon the use of asbestos wastemperature and found that the connections with

implemented in 2008 due to its effects on human

PTFE gasket are superior to the compressed asbestos

health.

fiber sheet gasket. ６）, 7）

Asbestos gaskets can be categorized into two major

Japan is prone to earthquakes: recent ones include thetypes: the spiral-wound gasket containing asbestos

Hyogo-ken Nanbu Earthquake in 1995, the Niigata-ken

filler, and the compressed asbestos fiber sheet gasket.

Chuetsu-oki Earthquake in 2007, the Tohoku Pacific

When the asbestos regulation was introduced,

Offshore Earthquake in 2011, and the Kumamoto

replacing the asbestos of the spiral-wound gasket with

Earthquake in 2016. In addition, according to some,flexible graphite filler did not cause any major

the Nankai Megathrust Earthquake is expected toproblem. However, regarding compressed sheet

occur within the next 10 years. There are manygaskets, it was difficult to replace the material forplants and buildings located near the postulated

several reasons, and so the compressed aramid-fiber

seismic center, which would likely suffer serious

sheet gasket was developed as an alternative to thedamage. In the Hyogo-ken Nanbu Earthquake,compressed asbestos fiber sheet gasket. However, itliquefaction caused bending on pipe flange

required a higher rubber content, which caused

connections, resulting in leakage of LP gas and thechallenges for heat resistance. While the flexible

issuance of an evacuation advisory to 70,000 people.

graphite sheet gasket had no problems in heat

Therefore, countermeasures against earthquakes areresistance, the gasket surface is vulnerable toessential for plants. Sawa et al. studied the mechanicalscratches because the material is brittle. Therefore,

behaviors of the flange connection with spiral-wound

the improved polytetrafluoroethylene （PTFE）

gasket when subjected to bending moment.８）-10） At theblended gasket came to be widely used. This gasket

Tightness Testing and Research Laboratory of Ecolehas excellent chemical resistance as well as heat

Polytechnique de Montreal（Canada）, the characteristics

resistance, and the conventional problems of creepof change in axial bolt force when flange connections

characteristics were overcome by devising formulation

with expanded PTFE gasket are subjected to bending

and production methods. Therefore, the improved

moment were studied. 11） Meanwhile, Koves et al.

PTFE blended gasket came to be used in many

described a method to evaluate the effects of bending

7

Technical Papers

moment using equivalent internal pressure.12）-16）

nominal diameter of the gasket was ASME/ANSI

However, there have been no studies on the pipeclass 300 4-inch with a thickness of 1.5 mm.

flange connection with PTFE gasket subjected toFlange hub stress and axial bolt forces werebending moment and internal pressure. As PTFE-

measured using the strain gauges; the leak rate wasblended gaskets are widely used, countermeasures formeasured with a helium leak detector according to thedisasters including earthquakes are required, and so it

sniffer method. The initial bolt tightening was

is important to evaluate the mechanical behavior of

conducted according to JIS B 2251“Bolt tightening

pipe flange connections with PTFE gasket.

procedure for pressure boundary flanged joint

This study aimed to determine the mechanicalassembly.”18） After bolt tightening, four-point bending

behaviors of the pipe flange connection with PTFE

moment and inner pressure were applied and thengasket subjected to bending moment and internalflange hub stress, change in axial bolt force and leakpressure using FEM stress analyses and experiments.

rate were measured. M, which is the bending moment

Firstly, the fundamental characteristics of a gasket

acting on the connection, was calculated using thewere measured according to JIS B 2490. In finite

equation M = W/2 ×α, where α is the effective pipe

element method（FEM）stress analyses, axial bolt

length（= 1.6 m）. The initial axial bolt force was 11.1

force, hub stress, and the gasket contact stresskN per bolt to give an average gasket stress 10 MPa;

distribution were calculated. In addition, leak rate was

the internal pressure applied on the connection was 2

estimated based on the gasket contact stress

MPa.

Winter 2018

distribution and fundamental characteristics. To verify
the method of FEM stress analyses, the FEM results
were compared with those from experiments on axial
bolt force and hub stress. In the experiments, leakrate from connections, axial bolt force, and hub stresswere measured.The connection size was ASME/ANSI
class 300 4-inch. The gasket used was the No. GF300,

No.34（a）Equipment

which contains no rubber and so suffers no chemicaldegradation due to heat and deterioration over time.
Accordingly, it is possible to conduct a precise
mechanical evaluation with the No. GF300.

2. Experimental method
Figure1（a）shows the experiment equipment used to
study the effects of bending moment on the pipe
flange connection; Figure1（b）outlines the equipment.
Through four-point bending, bending moment wasapplied to the pipe flange connection. In addition,internal pressure could be applied to the piping（b）Outline of the equipment
Figure1Experiment equipment used to measure themechanical behaviors of a pipe flange
connection subjected to four-point bending
moment3. Gasket characteristics

through a connected helium gas cylinder. The

For FEM stress analyses, compression and sealing

connection size was ASME/ANSI class 300 4-inch; thecharacteristics of gaskets were evaluated.

flange and pipe material was SUS304.

17）

Each pipe

was 2 m long, and the total length of the equipment

3-1）Compression characteristics

was approximately 4 m. To match the connection, theThe stress–strain curve of gasket at room8

Evaluation of the Mechanical Behaviors of Pipe Flange Connections with PTFE Gaskets Subjected to Bending Moment

temperature was evaluated. Figure2 shows an outline of
the experimental equipment used for the evaluation.19）
The size of the flange raised face is equivalent to thecompressed in a compression tester. Figure3 shows
the stress–strain curve of No. GF300 gaskets obtained
from the experiments. The strain value was calculated

leak rate

size stipulated in JIS 10K 50A; the raised face wasby averaging the indicated values of three displacementgauges to obtain the amount of compression, and thendividing the compression amount by the initial

Gasket contact stress
Figure4 Relationship between leakrate and gasket contact stressthickness to obtain the strain value.
Even though the gasket contact stress was increased3-2）Sealing performance

to approximately 40 MPa, the leak rate was too small

The sealing performance of gasket was evaluatedto be measured when the contact stress exceeded 20

using the equipment shown in Figure2 according toMPa, so no data is shown in the graph.

JIS B 2490. The pressure of the helium gas supplied
from the cylinder was increased to 2 MPa, then theleak rate from the gasket, which was collected using a

4. FEM stress analysis

Winter 2018sleeve, was measured with a soap-film flowmeter.

Figure5 shows the FEM model of the pipe flange

Figure4 indicates the relationship between the leakconnection with gasket subjected to four-point

rate and gasket contact stress obtained from thebending and internal pressure as shown in Figure1. In

experiment.

consideration of symmetry, the model was arranged
at 1/4 scale（axial direction = 1/2, circumferential

GasketNo.34

Compression

O-ringdirection = 1/2）. The threads of bolts and nuts were
Soap-film
flowmeter

Platenomitted, and the nut shape was simplified fromhexagonal to circular having the same cross sectional
area. Figure 6 shows a boundary condition for the

Sleeve

FEM stress analyses. In the illustration, the condition
was replicated in the following manner: 1）Symmetricfaces were fixed, and 2）Regarding bolt tightening,
tension equivalent to the axial force was applied to

Figure2 O utline of test equipment used to evaluate gasket
characteristics

each bolt model. Regarding four-point bending aftertightening the piping ends, a load of W/2 was applied
to jigs located around flanges. The effects of internalpressure were replicated by applying pressure to theinternal side of the pipe flange vessel. Flanges andbolts were modeled using elastoplasticity elements;

Stressgaskets were modeled using ABAQUS gasket
elements. In the FEM analyses, axial bolt force, flange
hub stress, and the gasket contact stress distribution
were calculated.
StrainFigure39Stress–strain curves of No. GF300 gasket

Technical Papers

the bolts, resulting in increased axial force. The
increased tension on the side of bolt #1 and #2 is dueto this increased axial force. On the other hand, thecontact surface of the flange closes. The closing
compresses bolts, reducing axial force on the side ofbolt #3 and #4. The results of the FEM analyses andW/2experiments matched well, verifying the robustness ofthe FEM stress analyses.

Axial bolt force

Tension side

Pipe flange
GasketBolt
Figure5

FEM model of a pipe flange connection

Compression
sideBolt #3

Bending moment
Figure7 C hanges in axial bolt force when bending moment is applied
to the pipe flange connection（The bending moment wascalculated from FEM stress analyses and experiments.)5-2）Gasket Contact stress distribution
Figure8 shows contour figures of the gasket contact
stress distribution at the following timings: when theflange was initially tightened; when a bending momentof 3500 N/m was applied to the pipe flange connection;

Bolt #2
Bolt #1
At tightening
Figure6Winter 2018

W/2

Bolt #4

Compression
side

Tensionside
At bending is applied

Boundary conditions in FEM stress analyses

5. Results‌of FEM stressanalyses and experiments

and when a bending moment of 3500 N/m and internalpressure were applied to the pipe flange connection.
The contact gasket stress is found to be zero at the
non-contacted gasket area, that is, at the most outerradius part of the gasket. The gasket contact stress
distribution at initial tightening indicates increasing
contact stress in the radius direction of the outside5-1）Change in Axial bolt force

diameter due to flange rotation. In the circumferential

Figure7 shows changes in axial force for the four bolts

direction, the contact-stress gradient is negligible.

shown in Figure6. The values were obtained by FEM

When a bending moment of 3500 N/m was applied,stress analyses and experiments. The abscissapart of the gasket’s contact stress significantly

represents the bending moment M ; the ordinate

decreased（left figure）; when internal pressure wasrepresents axial bolt force; the solid line represents theapplied, the gasket’s contact stress decreased further.

results of experiments; the dashed line represents the

Figure9 shows the gasket contact stress distribution in

results of FEM stress analyses. The axial force values

the outermost diameter contact area（r = 46.05 mm）inof bolt #1 and #2 increase with increasing bending

the circumferential direction at each step. The graphmoment, whereas those of bolt #3 and #4 decrease.

indicates marked changes in contact stress distribution

The contact surface of the flange opens due to bending

due to opening of the flange’s contact surface; themoment on the piping. The opening applies tension to

opening was caused by the bending moment applied
10

No.34

Evaluation of the Mechanical Behaviors of Pipe Flange Connections with PTFE Gaskets Subjected to Bending Momentto the flange.

exceeds approximately 3000N/m, the leak rate

Next, The leak rate from the connection is estimatedsubstantially increases. As Figure8 shows, part of theusing the contact gasket stress distribution obtained

gasket’s contact stress became zero due to bending

from the FEM and the fundamental leakage

moment; this zero stress appears to have caused the

20）
−21）

. Figure10 shows

substantial increase. The estimated leak rate and thethe estimated leak rate and the experimental results.

experimental results matched well, indicating the

As the bending moment increases, the leak ratevalidity of the FEM analyses and the method of

gradually increases; when the bending moment

estimating leak rate.

performance shown in Figure4

Gasketcontact
stressFigure11 shows the relationship between the
maximum principal stress in the axial direction, which
occurs at the flange hub, and bending moment. The

At initial tightening
Tension side5-3）Flange Hub stressgraph also shows values calculated using an ASME

Compression side

Boiler & Pressure Vessel Code Section Ⅷ Division 1“Rules for construction of Pressure Vessels”App.2,（2004）.（in this case, ASME values were calculated
under the condition of zero bending moment）.22） This

Winter 2018

when bending moment of3500 N/mwhen internal bending
pressure of 3500 N/m

Figure8 Gasket‌Contact stress distribution obtained from
FEM stress analyses

graph indicates that as the bending moment increases,
hub stress, which was evaluated from the experiments
and FEM stress analyses, increases. The results of theexperiments and FEM stress analyses matched well,indicating the validity of the analyses.

Step 1: Tightening
Step 2: Bending moment is applied
Step 3: ‌Bending moment and internalpressure are applied
Angle in the circumferential direction

Figure9Flange hub stress

Gasket contact stress

No.34

Gasket Contact stress distribution at each step

Bending moment
Figure11

Effects of bending moment on hub stress

6. Discussion
leak rate

6-1）‌Effects of nominal diameter ofconnection on axial bolt force behavior
The effects of nominal diameter on the axial force
behavior of the bolts in the connection were studied
Bending moment

by FEM stress analysis. Figure12 shows the greatest

Figure10 Comparison‌of leak rate from connection whenbending moment is appliedchanges in the increase and decrease of axial bolt force

11Technical Papers

when bending moment was applied to a pipe flange

application（solid blue line）. The ordinate represents

connection with a No. GF300 gasket. The nominal

the leak rate and the abscissa represents the bending

diameters were chosen as 4, 8, 12, 16, 20, 24 inches andmoment. When the bending moment exceeds 3000 N/

internal pressure was not applied. The ordinatem, the order of“Step 2: internal pressure application,

represents the axial bolt force ratio（=（Ff+Ft）/

Step 3: bending moment application”is associated withFf）,where Ff is bolt preload and Ft is an increment inslightly larger leak rate; however, the difference in leakaxial bolt force; the abscissa represents the bending

rate was small and almost at the level of error. In the

moment per bolt. the initial mean gasket contact stressexperiments, the order in which bending moment andwas 10 MPa; the maximum bending moment M, whichinternal pressure were applied showed no substantial

was applied to the flange, was 3500 N/m, indicating

effects on leak rate.

the following: the bolt number N increases whennominal diameter is greater, reducing the maximum
M/N. The solid line represents data for bolts subjected
to tension by bending moment; the dashed line
（contraction）by bending moment The figure indicates
the trend that the smaller the nominal diameter, thegreater the effects of bending moment on axial bolt

leak rate

represents the data for bolts subjected to compression

applied to the flange, the sealing properties are safer
when the nominal diameter is greater.

Bending moment
Figure13 Effects‌
on sealing performance of the order in which
bending moment and inner pressure are applied

Changes in axial bolt force

6-3）‌Effects of action point of bending
moment on leakage volume
As sown in Figure14, the effects of applying bending
moment at different points of bolt configuration werestudied. In Figure14（a）the bolts were arranged in a
vertically symmetrical manner; this configuration is
widely used（pattern A）. In Figure14（b）, two bolts
Bending moment per bolt

Figure12 E
 ffects of nominal diameter on behaviors of change
in axial bolt force in pipe flange connections
subjected to bending moment

are placed on the vertical line（pattern B）. Figure15
shows the relationship between leak rate and bending
moment for each pattern.
The results show that pattern A was associated with

6-2）‌Effects of the order in which bending
moment and inner pressure are applied

smaller leak rate than pattern B. Placing bolts at the

Figure13 shows the effects on the leak rate of thealleviate the reduction in contact pressure and sealingorder in which bending moment and inner pressure

performance; however, the commonly-used pattern A

are applied. The graph shows the results of leakage

was associated with greater sealing performance. In

tests which were conducted in the following two

pattern A, four bolts resist the opening force, whereasorders: Step 1: tightening, Step 2: bending-momentin pattern B, only three bolts resist the opening force.

application, Step 3: internal pressure application（solid

Therefore, in total, the opening appeared to be greater

red line）; and Step 1: tightening, Step 2: internalin pattern B.

position where the opening is largest was thought topressure application, Step 3: bending moment
12

Winter 2018

force. Thus, for the equivalent bending moment

No.34

Evaluation of the Mechanical Behaviors of Pipe Flange Connections with PTFE Gaskets Subjected to Bending Moment

Bending load

Bending load

bending moment per bolt as M/N, the evaluation
revealed the trend that the greater the nominal
diameter, the stronger the resistance to bending
moment.
（3） The gasket contact stress distributions wereobtained from the FEM stress analyses; therelationship between the leak rate and contact

Pattern A
Figure14

Pattern B

where bending moment is appliedstresswas obtained from the experiments.

Using the two results, leak rate was estimated.
The estimated and experimental values matched
relatively well, indicating the validity of both themethods of analyzing FEM stress andestimating leak rate.

leak rate（4） The effects on sealing performance of the orderin which bending moment and internal pressure
are applied were studied. The results indicatedBending moment

Winter 2018
No.34

Figure15 Effects‌of where bending moment on sealing
performance

7. Conclusions

that the order does not significantly affect leakrate.
（5） The effects of the action point of bending moment
on sealing performance were studied. The results
indicated that the common bolt arrangement（pattern A）is associated with greater resistanceIn this study, experiments and FEM stress analyses

to bending moment on the piping than is thewere used to study the mechanical behaviors of axial

arrangement in which two bolts are arranged onbolt force, hub stress, and sealing performance of thethe vertical line（pattern B）.

pipe flange connection with PTFE gasket subjected tobending moment. The following conclusions wereobtained.

8. References（1） FEM stress analyses were used to calculate the１）T. TAKAKI, K. SATO, Y. YAMANAKA, T. FUKUOKA,

gasket contact stress of a 4-inch pipe flange“Effects of Flange Rotation on the Sealing

connection subjected to bending moment andPerformance of Pipe Flange Connections”, ASME

internal pressure. When bending moment was

PVP Vol.478,（2004）,pp.121-128.

applied, the contact stress decreased on part of２）T . SAWA, N. OGATA, T. NISHIDA,“Stressthe gasket contact surface. When the bending

Analysis and Determination of Bolted Preload in

moment reached approximately 3500 N/m, thePipe Flange Connections with Gasket undercontact stress became zero, causing a rapid

Internal pressure”, Transactions of the ASME,

increase in leak rate.

Journal of Pressure Vessel Technology, Vol.124,（2） The results of the experiments and FEM stress３）T. KOBAYASHI, T. NISHIDA, Y. YAMANAKA,

force when bending moment was applied to the“Effect of Creep-Relaxation Characteristics offlange. The evaluation results indicated that theGaskets on the Bolt Loads of Gasketed Joints”,

results of the FEM stress analyses andexperiments matched well. In addition, when
13

（2002）,pp.22-27.

analyses were used to evaluate the axial bolt

ASME PVP Vol.457,（2003）, pp.111-118.
４）Ministry of Health, Labour, and Welfare, Cabinet

Technical Papers

Order on the Partial Revision of the Order for
Enforcement of the Industrial Safety and Health
Act, Cabinet Order No. 349（2008）.
５）Nippon Valqua Industries, Ltd., Gasket Catalogue,
Catalogue No. YC08（2016）.
６）K. SATO, A. MURAMATSU, T. KOBAYASHI, T.
SAWA, “FEM Stress Analysis and Sealing

316SS/GORE-TEX gasket style”, 1996.
12）W . J. Koves,“Analysis of Flange Joints Under
External loads”, Journal of Pressure Vessel
Technology, Vol.118, pp59-63,（1996）.
13）W. J. Koves,“Design for Leakage in Flange Joints
under External Loads”PVP2005-71254, Proceedingof ASME PVP 2005 Conference,（2005）.

Performance of Bolted Flanged Connections using14）E. C. Rodabaugh, S. E. Moore,“Evaluation of thePTFE Blended Gaskets under Internal Pressure”,

Bolting and Flanges of ANSI B16.5 Flanged Joints –PVP2015-45268, Proceeding of ASME PVP 2015

ASME Part A Design Rules”（1976）,.

Conference,（2015）.
７）K. SATO, T. SAWA, T. KOBAYASHI,“FEM STRESSANALYSIS of Long-term Sealing Performance for15）C. J. Dekker, H. J. Brink,“External flange loads and‘Koves’-method”, International Journal of Pressure
Vessels and Piping, Vol.79, pp145-155,（2002）.

Bolted Pipe Flange Connections with PTFE

16）W. Brown,“Improved Analysis of External Loads on

Blended Gaskets under Elevated Temperature”,

Flanged Joints”PVP2013-97814, Proceeding of

PVP2016-63372, Proceeding of ASME PVP 2016

ASME PVP 2013 Conference,（2013）.

Conference,（2016）.
８）T. SAWA, Y. TAKAGI, K. SATO, Y. OMIYA, H.
performance of pipe flange connection with gaskets

Fittings”,（1996）.
18）Japanese Industrial Standards JIS B 2251“Flange
Joint Assembly Guidelines”（2008）.

under external bending moment and internal19）Japanese Industrial Standards. JIS B 2490“Testpressure”, PVP2012-78411, Proceeding of ASME PVP

method for sealing behavior of gaskets for pipe

2012 Conference,（2012）.

flanges”,（2008）.

９）Y. Takagi, H. Torii, T. Sawa, K. Funada,“Evaluation20）Y. OMIYA, T. SAWA, Y. TAKAGI,“Stress Analysis

of Sealing Performance of Pipe Flange Connection

and Design of Bolted Flange Connections under

Subjected to External Bending Moments”,

Internal Pressure”, PVP2014-28606, Proceeding of

PVP2009-77494, Proceeding of ASME PVP 2009

ASME PVP 2014 Conference,（2014）.

Conference,（2009）.

21）Y. OMIYA, T. SAWA,“Stress Analysis and Sealing10）F . Ando, T. Sawa, M. Ikeda, and T. Furuya,

Performance Evaluation of Bolted Pipe Flange“Assessing Leakage of Bolted Flanged Joints under

Connections with Smaller and Larger NominalInternal Pressure and External Bending Moment”,

Diameter under Repeated Temperature Changes”,

Proceeding of ASME PVP 1998 Conference, 376,

PVP2014-28730, Proceeding of ASME PVP 2014
Conference,（2014）.

pp.39-44,（1998）.
11）TTRL Tightness Testing and Research Laboratory,22）ASME Boiler & Pressure Vessel Code Section Ⅷ“Room temperature external bending moment

Division 1“Rules for construction of Pressuretightness test（ROBT）on the selco seal 4”cl 150 lb

Vessels”App.2,（2004）.

Koji Sato
Corporate Research andDevelopment Group
Product Development DivisionⅠ

Toshiyuki Sawa University of Hiroshima
Riichi Morimoto Mitsubishi Chemical Corporation
Takashi Kobayashi Numazu College
Yuta Motono
Corporate Research and Development Group
Product Development Division Ⅰ
14Winter 2018

DOI,“Effects of scattered bolt preload on the sealing17）ANSI/ASME B 16.5,“Pipe Flanges and Flanged

No.34

Performance Evaluation of
Improved EPDM Material under
High-temperature Environments
1. Introduction

Winter 2018
No.34

Figure1 schematically illustrates the characteristics of
the improved EPDM material and existing silicone

In the case of a severe accident（hereafter, SA）, therubber and fluororubber sealing materials, based on

primary containment vessel（PCV）is surrounded byprevious evaluation results of each material. The

high-temperature steam at 200ºC and high radiation

horizontal axis represents steam temperature and thedose of several hundred kGy. Therefore, the PCV

vertical axis radiation dose. The figure shows that

requires a sealing material that can maintain sealing

silicone rubber and fluororubber cannot maintainperformance even under an SA environment. For suchsealing performance in the event of SA; on the othercases, we evaluated the performance of our improved

hand, the new EPDM material maintains sealing

EPDM material（No. H3070）under high-temperature

performance even in high-temperature steam of overenvironments.

200ºC and γ ray irradiation of over 800 kGy.

Previously, silicone rubber and fluororubber, whichThus, the improved EPDM material was confirmed togenerally have excellent heat resistance, have beenoffer adequate environmental performance in theused as sealing materials for PCV. However, in an

event of SA, and was determined to be used as a newenvironment with high-temperature steam of 200ºC

sealing material for PCV. For this application, it wasand high radiation dose of several hundred kGy, thecrucial to confirm the following two matters:

structural weaknesses of polymers cause theconfirmation of the limit conditions under which theprogression of reduction in molecular weight due toimproved EPDM material can maintain sealinghydrolysis and due to exposure to high energies

performance, and verification of the improved EPDM

including γ rays. This is likely to lead to the loss ofmaterial’s superiority under SA environments.

sealing performance, and so a new material was

Therefore, an evaluation under a high-temperature

considered necessary.

１）

The improved EPDM material was developed on theassumption that it would be used in high-temperature
steam, and we have proposed the new material forsuch applications. We have been conducting various
evaluations to confirm its sealing performance, using asteam environment at a high temperature of 200ºC
and atmospheric pressure of 0.854 MPa as basic
conditions which properly allow a PCV to containradioactive material in the event of SA. Various tests
were conducted under these conditions and theimproved EPDM material was confirmed to haveadequate sealing performance. ２）
15

Figure1

General characteristics of sealing material

Technical Papers

environment in which the temperature significantly２-2）Evaluation method

exceeded SA temperatures was conducted.

2-2-1）Compression-set test

Regarding the evaluation method, the following tests

Two evaluation methods were used to confirm thewere conducted to confirm sealing performance:

performance at 300ºC, one of which was thecompression-set tests, which are effective for verifying

compression-set test, which is very effective forthe lifespan of the seal, and leakage tests using small

confirming the lifespan of a seal.

flanges, which imitate flanges installed on actual

The method of measurement conformed to JIS K

equipment.

6262:2013“Rubber, vulcanized or thermoplastic –Determination of compression-set at ambient, elevatedor low temperatures.”The JIS large specimen

2. Evaluation（cylindrical specimen with a diameter of φ29 mm and２-1）‌Preliminary test to set the evaluation
temperature

thickness of 12.5 mm）was used as the sample shape;This evaluation aimed to confirm the limitation of

Plastic deformation which occurs at high temperatures

sealing performance of the improved EPDM material;and under compressed conditions（but not only high-the evaluation was conducted at temperatures up totemperature conditions） was quantified. The

the temperature at which the improved EPDM

quantification was defined as follows: 0%: the original

material showed no significant material changes.

shape is completely restored; 100%: no shape

Thermogravimetric analysis was used as therestoration occurs. Rubber deterioration can beevaluation method. In Figure2, the purple line

considered to be a chemical reaction. Therefore, therepresents the rate of weight loss due to heat. Weighttime taken to reach a given deformation can beloss begins to occur at a temperature of over 300ºC. No

estimated by plotting a graph with time on the

major change was found to develop in the main

horizontal axis and compression-set rate on the verticalbackbone structure at temperatures up to 300ºC.

axis as shown in Figure3.

the compression rate was 25%.

No.34

temperatures up to 300ºC.

Figure2

Winter 2018

Therefore, the performance was evaluated at

Results of thermogravimetric analyses
16Performance Evaluation of Improved EPDM Material under High-temperature Environments

imitate the flanges installed on actual equipment, wereused to confirm whether the sealing performance
could be maintained at the temperatures andpressures of SA. Figure4 schematically illustrates thesmall flange and Table2 shows their sizes. The crosssectional shape and size of the flange’s groove are
equivalent to those of the actual equipment; the crossFigure3

Winter 2018
No.34

Compression-set test and expected lifespansectional shape and size of gaskets were also
equivalent to those of the actual equipment. In the

Table1 shows the evaluation conditions. To take theevent of SA, the flanges of the PCV open due to innerconditions in the event of SA into consideration, thepressure. To imitate this phenomenon, an adjustingevaluation was conducted under the following

shim was inserted into the smooth part in the small

conditions: atmosphere: saturated steam environment,

flange, and the opening area was then adjusted. After

exposure dose of γ rays: 800 to 1000 kGy, temperature:

the adjustment, He gas was used to apply pressure to

200 to 300ºC. Regarding the environment within a PCV

the inside of the small flange. This pressurizationin the event of SA, the maximum atmosphericenabled leakage tests to be conducted underpressure was assumed to be 0.854 MPa. On the otherconditions imitating those in the actual equipment.

hand, this evaluation was conducted under a saturated

As Table3 shows, the test conditions were as follows:

steam environment, resulting in much greaterpressure applied to the specimens（saturated steampressure at 200ºC: 1.6 MPa, at 300ºC: 8.6 MPa）.
Therefore, the environment is much more severe thanin a PCV in the event of SA.
2-2-2）Leakage tests using small flanges

Leakage tests using small flanges were conducted as
the second evaluation method. Small flanges, which
Table1

Conditions for compression-set tests

Figure4

Outline of a small flange

Table2

Sizes of small flanges

Table317

Conditions for leakage tests

Technical Papers

After the flange temperature reached a given
temperature, He atmosphere of 1 MPa was used topressurize the inside of the flange for 10 minutes.
After the pressurization, the presence of leakage wasconfirmed. If He gas leaks in this test, the leakage canbe confirmed from the outside of the flange. Therefore,
the leaked He gas was collected through water as a
substitute to calculate the hourly leakage rate of He.
Figure 5 outlines the test equipment.

Figure6

Specimen after Test No. 6-3 test

Figure6 shows an external view of a specimen tested
under the most severe conditions with a temperatureof 300ºC and duration of 168 hours（Test No. 6-3）.
Figure5 Outline‌of test equipment to determine leakage
from a small flange

dents were found around the center of the sealing
surface. Therefore, the specimen was cut and thecross section was checked. Although the dents were３-1）Compression-set testcaused by a crack that had developed inside, theTable4 shows the results of the compression-set tests.

crack was confirmed not to have penetrated into the

In the table, Cs represents the compression-set rate.

sealing surface. The cause of the crack appeared to be

The following trends were confirmed: under aa rapid expansion of compressed steam while theconstant temperature, the compression-set ratepressure was being reduced under highly-pressurized

increases over time; within a given time period, thesaturated steam. To be more specific, the crack iscompression-set rate increases with increasing

considered to have developed as follows: 1）Steamtemperature.

pressure of 8.6 MPa was applied to flanges for the

Table 4

Results of compression-set tests

evaluation under a saturated steam environment at
300ºC. 2）The steam pressure also compressed steam
contained in the rubber. 3）After the evaluation wascompleted, the highly-pressurized steam was released
from the pressure container. 4）During steam release,
rapid decompression occurred. 5） The rapid
decompression caused steam, which had been
compressed in the rubber, to expand rapidly. 6）The
rapid expansion caused the crack in the rubber.
In this evaluation, the crack was caused by a physicalfactor stemming from the evaluation equipment. On
the other hand, in the event of SA, the maximum
pressure is expected to be 0.854 MPa, and so it isconsidered that no crack will develop in actual
18

Winter 2018

3. Evaluation results

Although no abnormality was found on the side face,

No.34

Performance Evaluation of Improved EPDM Material under High-temperature Environments

compression-set rate of 80%. ３）２）Time duration was
set such that a compression-set rate of 80% could beachieved within the time duration. 3） Eachtemperature was arranged according to the time
duration. As a result, the plot demonstrates that acollinear approximation can be made with very highcorrelation coefficients.
Since thermal deterioration is a chemical reaction, theprogress of deterioration varies depending on theamount of thermal energy which is applied to thematerial. Therefore, regular deterioration behaviors
are likely to be detected provided that thetemperature range does not significantly exceed thethermal limit for the material and the evaluation
Figure7Winter 2018
No.34

A plot of the results of compression-set tests

environment is not unstable.
Therefore, in this evaluation, which was conductedequipment in the event of SA.

under a saturated steam environment of 200 to 300ºC,

Figure7 illustrates the results of the compression-set

the deterioration had developed according to thetests. The horizontal axis represents time; the verticalchemical-reaction theory, and was not likely to cause

axis represents compression-set rate. Under suchsudden and abnormal deterioration. Therefore, lifetime

conditions, the resulting data were plotted to produce

estimation was confirmed to be possible with thisan approximation curve for each temperature. As

deterioration.

Figure7 shows, each curve shows a very highcorrelation coefficient, and the slopes of the respective３-2）Leakage test using small flanges

approximation curves are approximately the same.

The results from leakage tests using small flanges

Figure8 is an Arrhenius plot of the results of theshowed that no leakage occurred from the specimen

Arrhenius equation under the following conditions: 1）

which had been exposed to the saturated steam

Sealing performance can be secured at theenvironment at 280ºC and 300ºC for 168 hours.
After the evaluation had been completed, the small
flanges were dismantled to check the appearance ofthe gaskets. Figure9 shows a photograph of a
specimen which was exposed to 280ºC for 168 hours;
no abnormality was found in the appearance.
Similarly, regarding a specimen which was exposed to
300ºC for 168 hours, cracks were confirmed on part of
the gasket in the direction of the outer circumference;
however, no cracks or damages, which affect leakage,were confirmed in the direction of inner or outercircumference. Regarding the abovementioned cracks,
like the internal cracks in the compression-set tests,
rapid expansion of compressed steam due to rapid

Figure8 Arrhenius‌plot based on data at temperatures of
200 to 300ºC
19

decompression appears to have caused the cracks.
Therefore, at 168 hours after the initiation of exposureTechnical Papers

・These results indicate that the improved EPDM
material can be used in a stable manner undersaturated steam environments at temperatures up
to 300ºC.

5. Conclusion
In this evaluation, the improved EPDM material was
confirmed to maintain its sealing performance evenunder the very severe environment of 300ºC, provided
the environment was limited to that used in thisevaluation. This finding highlighted the importance of
Figure9Specimen after Test No. 7-1 leakage tests

continuing with development and verification based on
unconventional, free-thinking without bias, as well as

under saturated steam environments at 280ºC andlistening to users’requests. We will continue to strive

300ºC, no significant defect of sealing material was

hard to produce such reports in the future.

confirmed. Therefore, the sealing performance

Note that this report is an edited version of a paper

appears to have been maintained.

presented at the autumn academic lecture session of

4. Summary
The results of the compression-set tests and leakage

Lastly, we sincerely thank the staff of Chubu ElectricPower Co., Inc. for their assistance in publishing thisreport.

tests using small flanges under high-temperaturesaturated steam environments were as follows.

6. References

・The mechanism of deterioration of our improved
EPDM material（No. H3070）appeared to be the１）Koji Ito,“Radiation Resistance of Elastomer forsame at temperatures ranging between 200 and

Vacuum Seals,”Proceedings of the 27th Linear

300ºC; the possibility of sudden abnormal

Accelerator Meeting in Japan, 7P-19.

deterioration developing due to temperature２）Ken Suzuki, Valqua Technology News, No. 30, 14-19

changes is low.

（2016）.

・The results of the leakage tests using small flanges３）Toshio Kawamura,“O-ring’s life span and reliability,”

showed no leakage when the flanges had been

Valqua Review, Vol. 26（1982）.

exposed to saturated steam at 300ºC for 168 hours.

Ken Suzuki
Corporate Research andDevelopment Group
Product Development DivisionⅠ

Winter 2018

the Atomic Energy Society of Japan in 2017.

Shinichi Matsuda


CHUBU Electric Power Co.,Inc.



CHUBU Electric Power Co.,Inc.

Takuya Sugimura

20

No.34

Guidelines on Gasket Selection,
Selection Troubles, andCountermeasures
1. Introduction

Temperature

As Figure1 shows, we previously reported that poor

Fluid

Pressure

installation and poor selection account for a majority
of sealant troubles at plants; troubles due to mis-

Optimalgasket selection

FlangeDimension

selection account for approximately a quarter of all
troubles. １） To ensure that sealants function properly,

Tolerant leakage volume

Tightening force

appropriate selection is essential.

Cost

This article introduces issues regarding gasket

Winter 2018selection, selection methods, troubles due to selection

Results of study on leakage causes (petroleum refining and chemicals)

No.34

Studied by Nippon Valqua
2004–2013, within Japan

Figure 1

Selection conditions for gaskets

example, for flanges with abnormal shapes or

errors, and countermeasures.

Misinstallation
Misselection
OthersFigure2Workability

Misinstallation
Misselection
OthersStudied by The High-Pressure Gas
Safety Institute of Japan 2007–2011

Statistics from study of leakage causes

2. Guidelines on gasket selection

extremely narrow sealant surfaces, the spiral-woundgasket cannot be used; other gaskets such as the sheet
gasket should be selected. In some cases, gaskets with
non-standard dimensions should be made or flanges
should be changed.
In addition, allowable leakage volume, tightening force,cost, and workability should be considered. Whenpriority is put on functions such as small leakage
volume, the product may become expensive.
Accordingly, priority conditions should be taken into
account and then optimal gaskets should be selected.

２-1）Issues regarding gasket selection

In addition to the above conditions, the places where

Gaskets are used under various conditions and so agaskets are used should be considered, as the types ofwide range of conditions must be considered and thengaskets that can be used may be limited depending on

the optimal gaskets chosen. Firstly, we will study thethe application and equipment. Table1 categorizes

conditions that should be considered when selecting

commonly used gaskets by equipment and device. ２）

gaskets, as shown in Figure2.

For example, gaskets used for devices such as the

The main conditions that must be considered without

casing of pumps have complex shapes and are usually

fail are fluid, temperature, and pressure. These threethin, so only gaskets which meet such requirements

conditions must always be considered when selecting

can be selected. In addition, in important stages ofgaskets.

manufacturing processes and in areas where leakage

Next, the shapes and dimensions（diameter, thickness,would significantly affect the surrounding areas, aand width）of flanges need to be confirmed. For

more reliable gasket material must be selected.

21

Technical Papers

Table1

Gasket type

PipingNon-asbestos joint sheet◎
Foamed carbon gasket○
PTFE-coated gasket◎
PTFE gasket containing filler◎
Spiral-wound gasket◎
Serrated metal gasket with foamed carbon○
Metal jacketed-gasket○
Metal flat gasket△
Serrated gasket△
Ring joint gasket◎
SymbolTable2

Applicable equipment for gaskets
Heat
exchanger

tank,
Valve Tower,
Pump
reactor

◎
△
○
○
◎
◎
◎
○
○
△

◎
○
○
◎
◎
△
○
△
△
◎

◎
△
◎
◎
◎
○
○
○
○
◎

Fluid category and typical fluids

Fluid category

Equipment and device
◎
○
○
○
◎
△
△
△
△
△

◎：Frequently used○：Used△：Although rarely used, usable depending on conditions.

Typical fluids

Fresh water, industrial water, warm water, hot
Water,① hot water, water, water vapor, superheated vapor, boiler
water vapor water, drain, municipal effluent, sewage, etc.

②

Crude oil,alcohol,animal-/plant-based
oils, heattransfer oil,etc.

③

General（including B.T.X.） ketones, amines, ethers,
solvents,
phenol, acrylonitrile, etc.
weak acids,
Acetic acid, formic acid, oxalic acid, citric acid,weak
alkalis, etc. boric acid, phosphoric acid, etc.

Crude oil, naphtha, oil gas, gasoline, light oil,kerosene, heavy oil, tar, fuel oil, lubricating oil,common mineral oil, hydraulic oil, methanol,
ethanol, ethylene glycol, glycerin, animal-/plantbased oils, heat-transfer oil, etc.
General solvents, aromatic hydrocarbon

Strongacids and④ strong

alkalis２-2）Gasket-selection procedure

Air, nitrogen

Ammonia, sodium carbonate, etc.
Sulfuric acid, nitric acid, hydrochloric acid,permanganic acid, etc.
Sodium hydroxide, potassium hydroxide, calcium
hydroxide, barium hydroxide, lithium hydroxide,
black liquor, etc.

Figure3 shows the gasket-selection procedure. The⑤ gas, inert

details of each step are as follows:⑥ Exhaust gas Exhaust gas

gas, etc.

Air, nitrogen gas, helium, argon, neon, etc.

Combustible Hydrogen, methane, ethane, propane, butane,

Fluid category⑦ gas

Poisonous⑧ gas⑨

Oxygen andOxygen, ozone, liquid oxygen
others⑩

Cryogenic LNG, LPG, liquid nitrogen, liquid hydrogen,fluidliquefied ethylene, liquefied argon, etc.

Fluid matching table

Winter 2018

Pressure/temperature rating table

ethylene, acetylene, propylene, etc.
Ammonia, carbon monoxide, phosgene, sulfur
dioxide, vinyl chloride, vinyl acetate, methyleneoxide, fluorine, chlorine, bromine, iodine, hydrogensulfide, sulfurous acid gas, etc.

Class

Flange’s conformanceClass

Selection conditions for gaskets

STEP 1 Fluid category

e
or c
ted
Sat

ura

Class
Class

Pressure

Figure3

-va
p

Class

Gasket’s shape and dimension

High-performance Joint sheet（Vapor pressure）
sheet
High-performance sheet
Spiral-wound gasket Spiral-wound gasket（Foamed carbon） （Inorganic paper）
Spiral-wound gasket（Mica）

in use. There are 10 fluid categories as listed below.

Ring joint

Table2 summarizes the typical fluids of each category.

Select an appropriate pressure/temperature selection

Recommended Other usablegaskets
gaskets
Joint sheet

Class

Confirm the fluid category based on the types of fluid

STEP 2 Pressure/temperature rating table

No.34

urv

Class

temperature

Figure 4‌Temperature/pressure selection graph for water,
hot water, water vapor

graph for the fluid category. Then, select usableconditions intersect at the point ② , so a high-gaskets based on the pressure and temperature which

performance sheet gasket is selected.

will be applied to the gaskets. For example, when thefluid is water vapor with a pressure of 1 MPa and a

STEP 3 Fluid matching tabletemperature of 180C, the fluid category is ① water,

Use the fluid matching table to confirm whether the

hot water, and water vapor. Figure4 shows a selection

gasket selected in Step 2 can be used for the intended

graph. In the graph, the pressure and temperature

fluid. If the gasket is not suitable, go back to Step 2
22

Guidelines on Gasket Selection, Selection Troubles, and Countermeasuresand select“other usable gaskets”or higher-category

Table5 Matching table for flange seats and spiral-wound gaskets

gaskets. Table3 shows a fluid matching table for

26 ～
60B

①

water, hot water, and water vapor as an example.
Under the conditions shown in Step 2, the fluid iswater vapor. Therefore, the selected high-performance
sheet gaskets are considered to be applicable.
Table 3NominaldiameterNominalpressure

Gasket seat

With inner andouter rings

Raisedface
With outer（flat face）
ring（1）（2）With inner ring

Male-andfemale
shape

Class
150

Class
Class
300 to 600 900 to 1500

With inner and outer rings（2）
With outer ring（1）With inner ring

Matching table for water, hot water, water vapor

SF300

・ 6500AC
6500

・ 6503・ 6503AC
6502

7010-EX
7GP66S

7020

7026

・ VF-35E
VF-30・ 8590TN
8590 Series
8590L Series

6590 Series

7590 Series

M590 Series
M590L Series

N7030 Series（ reference
）
1500

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

clear water・industrial ○
water

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

steam・superheat steam ○

○

○

○

△

△

○

○

○

○

○

○

○

○

○

○

drain・municipal effluent・○
dirty water

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

STEP 5 Gasket’s shape/dimensions

calcium chloride

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

sodium chloride

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

Finally, determine the gasket’s shape and dimensions

seawater

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

sodium nitrate

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

sodium fluoride

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

Sodium sulfate

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

Highperformance
sheet

Type of Fluid

Fluid

・
7010
・
7GP66

GF300

Basic shape

UF300

Groove
shape

MF300

Basic shape（3）warm water・hot water・ ○boiler feedwater

Fluid Segment

aqueous solution of a neutral salt

water’hot water’steam

・ steamwater

Winter 2018
No.34

1/2 ～
24B

Note（1）‌When filler is foamed carbon or PTFE, gaskets with innerand outer rings are recommended.
（2）‌When fluid is monomer, gaskets with inner and outer rings
are recommended.
（3）‌In the case of flanges with large nominal diameter, gaskets
with inner rings are recommended for easy handling.

to confirm whether the gasket can be manufactured. If
the gasket cannot be manufactured, go back to Step 2
and re-select.
In addition, confirm whether the selected gasket canaccommodate the gasket’s tightening force. Regarding
ease of tightening/removal, cost effectiveness, andSTEP 4 Flange’s conformance

Confirm whether the selected gasket can be usedmarket availability（delivery）, determine which factors

for the shape of the flange’s gasket seat. Table4 is ashould be prioritized and select the optimal gasket.

matching table to check whether a selected soft

When selecting gaskets based on fluid, temperature,gasket is suitable for a flange’s gasket seat. Table5 is aand pressure conditions, please use our Gasket catalog

matching table to check whether a selected spiral-（No. YC08）and Seal Quick SearcherTM, which is awound gasket is suitable for a flange’s gasket seat anduseful website for selection. ３）

nominal pressure/diameter.
Table4

Matching table for flange sheets and soft gaskets
GasketFlange-seat typeMale-andFlat face Raised face female
shape

Type

Groove
shape

Shape

２-3）‌Fluids which require care when selecting
The following fluids require particular care whenselecting:①

Oxygen and combustion-supporting gas: Gaskets
containing combustible material should be

Joint sheet/highperformance sheet
Fluororesin sheet（containing filler）

avoided.

FF

●

●

－

FR

●

●

● by

FF
Fluororesin sheet（Simple substance） FR

－

－

－

－

PTFE-blended gasket, copper jacketed-gasket,

－

－

●

●

FF

▲

－

－

－

and solid-metal flat gasket are recommended.

FR

●

●

－

－

Fluororesin jacket
Foamed carbon
sheet

－
16K

● by

20K

	Spiral-wound gaskets containing PTFE filler,②

P o l y m e r i z a b l e m o n o m e r : P o l y m e r i z a b l e

FF

▲

－

－

－

monomers including styrene monomer and vinyl

FR

●

●

▲

▲

chloride monomer can cause malfunctions in the
joint sheet and PTFE-blended gasket. The spiralwound gasket with inner and outer rings and the23Technical Papers

metal gasket are recommended.
③

3. Troubles‌
due to mis-selection andcountermeasures against the troubles

 Fluid containing slurry: Soft gaskets can bedamaged and leak due to erosion.

	The spiral-wound gasket with inner and outer

Previously, examples of troubles due to fluid

rings and the metal gasket are recommended.

mismatch were introduced.４） Following are otherH eat-transfer oil: The joint sheet can suffer

examples of troubles due to mis-selection.

④

deterioration in its rubber binder, resulting in⑤leakage. Moreover, oil has high permeability.

３-1）Thermal degradation in the joint sheet gasket

Therefore, the spiral-wound gasket containing

One of the constituent materials of the joint sheet

non-asbestos filler can suffer leakage when usedgasket is a rubber binder. When the temperature

for a long time. The foamed-carbon sheet gasket

exceeds 100ºC, the binder hardens, making the wholeand spiral-wound gasket containing foamed

gasket harder. In this state, external force such ascarbon filler are recommended.

additional tightening and piping stress can cause theRadioactive fluid: PTFE is vulnerable to radiation,

gasket to crack as shown in Figure5. When additionaland so PTFE gaskets are not recommended.

tightening is applied during maintenance, the joint
6

Foamed carbon has radiation resistance of 1.0×10 Gy;

sheet gasket should generally be used at amake a selection after checking the radiation dose.

temperature of less than 100ºC. If the temperature isover 100ºC, high-performance sheet gaskets including
No. GF300, which does not contain rubber binder, areTable6 shows the relationship of gasket thickness torecommended.

gasket characteristics regarding the seat gasket. The
thicker a gasket is, the greater its compression
amount. A thicker gasket can better absorb a flange’s

Winter 2018２-4）Thickness selection

strain and swelling. On the other hand, the thinner agasket is, the smaller the penetration-leakage volume

No.34

is, resulting in superior sealing properties. At the sametime, a thinner gasket has weaker creep relaxation,
resulting in superior long-term stability. In terms ofcompression-failure characteristics, thinner gaskets are
more tolerant to external force. From the above,
Figure5thinner gaskets are recommended in principle.

Cracked joint sheet gasket due to hardening

However, when flanges with large nominal diameters

On the other hand, when gaskets are used inhave large swelling and strain in the flange and whenequipment, to reduce the leakage volume andflanges have some roughness on the surface due todeterioration, thinner gaskets are used to cause stresslong-term use, the strain needs to be absorbed.

relaxation less frequently, or the gaskets are initially

Therefore, thicker gaskets are recommended.

tightened at a contact pressure of over 30 MPa.4）

Table6 Gasket thickness and characteristics（sheet gasket）

When the joint sheet is used at temperatures

Characteristics

exceeding 100ºC, the following countermeasures are

Gasket thickness
Thin

Thick

recommended to avoid additional tightening:

Compression amountLittleLarge① Set the gasket thickness at 1.5 mm or less.

Seal property

StrongWeak②

Creep relaxation

LittleLarge

Compression failure contact pressure

StrongWeak

Apply gasket paste（including seal paste）to thegasket.

③

Set the initial tightening contact pressure at over24

Guidelines on Gasket Selection, Selection Troubles, and Countermeasures

30 MPa.
④

Use a joint sheet gasket in areas where pipe stressis less likely to occur and where gaskets can be
replaced easily.

⑤ T o increase the gasket-tightening contactpressure, use a ring gasket with a gasket outer
diameter equal to the bolt’s bore diameter.
３-2）‌Deformation of fluororesin-blended sheet gaskets
Fluororesin-blended gaskets tend to occur creep
relaxation even at room temperature. Especially, whengaskets made solely from fluororesin are used,

Figure7

Deformation of a spiral-wound gasket

deformation due to creep relaxation must be
considered carefully; in principle, grooved flanges

inner and outer rings is recommended.

should be used.

When the fluid is a monomer, the gasket with innerIn addition, the creep relaxation characteristics ofand outer rings is also recommended to inhibit

fluororesin become more prominent at highpenetration and polymerization.

temperature, leading to greater deformation due toWinter 2018softening as shown in Figure6. Therefore, when the３-4）Troubles due to errors in selecting dimensions

temperature exceeds 100ºC, a filler should be added, orOriginally, the gasket’s dimension must be set togaskets containing less fluororesin should be selected

match the flange’s dimension. If they do not match, thein order to reduce creep relaxation.

gasket may leak. For example, when the gasket’s
diameter is smaller than that of a raised-face flange,
the gasket will cause inaccurate centering, causing
misalignment and partial narrowing on the gasket’s

No.34

contact surface as shown in Figure8. The narrowcontact surface cannot bear the inner pressure and ispushed toward the outer diameter, sometimes
resulting in deformation or rupture. The misalignment
also pushes the whole gasket within the piping’s innerdiameter. The protrusion may damage the gasket andcause leakage.
Figure6

Deformation of a fluororesin sheet gasket３-3）Deformation of spiral-wound gaskets
Regarding spiral-wound gaskets containing foamed-

Gasketcarbon filler or PTFE filler, when a spiral-wound

Flange seatgasket with outer ring is used, the filler slides. As
shown in Figure7, the sliding may cause buckling
deformation on the inner-diameter side, weakening thesealing properties. Therefore, when the filler isfoamed carbon or PTFE, the spiral-wound gasket with
25

Figure8

Deformation due to gasket misalignment

Technical Papers

３-5）Troubles due to corrosion

metals, a cell is formed, sometimes resulting in

One example of gasket-induced corrosion is“deposit

corrosion of the flange. To prevent this corrosion, thecorrosion,”which occurs by fluid penetrating the gap

flange joint assembly must be insulated. Highbetween the gasket and flange or the gasket itself,

insulation gaskets include fluororesin-blended gaskets

then chlorine ions in the fluid cause corrosion.

such as fluororesin jacketed-gaskets. Not limited to

Especially when stainless-steel flanges are used ingaskets, insulation, including the use of insulating bolts

seawater, which contains many chlorine ions, corrosion

to insulate screw parts, is recommended.

is more likely to occur. Tightening contact pressure is
weak in the inner-diameter area of the contact surface
between a flange and gasket, resulting in minute

4. Conclusion

spaces more frequently. When fluid containing chlorine

This report explained gasket selection, selection

ions penetrates the gap between the stainless-steelmethods, troubles due to selection errors andflange and gasket or penetrates within the gasket, thecountermeasures. For further details on gasket

stainless steel forms a passivation film. This reaction

selection, please refer to our Gasket catalog（No.

creates an oxygen concentration cell, reducing pH and

YC08）and Seal Quick SearcherTM, which is a usefulincreasing the chlorine-ion concentration and leading to

website for selection. For other selection conditions

rapid deterioration of the flange metal or deposit

than described in the catalog or website, pleasecorrosion.

5）

To prevent this deposit corrosion, it iscontact us.
We believe that by studying the issues and procedures

and to apply an anticorrosion paste（seal paste）toregarding proper product selection, leakage troubles

eliminate the gaps. Regarding tightening, the following

due to gaskets can be prevented. We hope this reportmeasures may be used: apply a greater gasket contact

was helpful.

pressure, modify the flange’s strain, and smooth theflange seat.
Galvanic corrosion may develop at the junction
between different metal flanges, and occurs as follows:1）Metals with different ionization tendency come into

5. References
１）‌R. Ikeda, Valqua Technology News No. 31, pp. 2–7;
2016.

contact with each other, 2）When the metals are２）‌Valqua Handbook. No. 92（2011）.

immersed in an electrolyte solution, a potential

３）‌T. Enisi, Valqua Technology News. No. 32, pp. 22–25

difference occurs in the space between the metals,
forming a galvanic cell, and 3）The galvanic cellcorrodes the metal with lower ionization tendency.
When gaskets with high conductivity including metals
are used in a flange’s junction between different

Winter 2018

effective to use a gasket with a low chlorine content（2017）.
４）‌T. Enisi, Valqua Technology News. No. 33, pp. 2–3;
2017.
５）‌T. Nishida: New Gaskets and Gasketing Technology.
p. 87（2015）.

Asuka Matsushita
Sales Group
Technical Solution Division
26

No.34

Considerations for Tool Selection
and Installation of Fastening Bolts for
Flanges with Large Nominal Diameters
1. Introduction

2. Selection of optimal tools

Various tightening tools are used for fastening bolts.

Firstly, using tools offers the following benefits:

Correctly selecting the optimal tools depending on the

Benefits associated with installation quality:

usage environment and required fastening precision

・Correct fastening force can be applied to bolts.

and properly using such tools reduces the workload

・Gaskets, flanges, and bolts are not overloaded.

and improves fastening precision, work efficiency, and・‌Tightening will be consistent if it can be managed

safety.

based on torque values and axial force values.

Bolt fastening is required not only during plant

Winter 2018

construction but also maintenance and inspection.

Benefits associated with operation:

However, bolt fastening is difficult to control and so・‌Work time can be decreased by reducing staff

even now it still depends on the operator’s instincts
and experiences. In addition, as the number of skilled
operators decreases, bolt fastening is becoming amajor cause of leakage accidents and fires at plants.

No.34

Despite this situation, training on bolt tightening,

number and operation time.
・‌Heavy manual work can be eliminated, reducing theburden on operators.
・‌Tightening can be executed even in narrow areas
where there is little space around equipment.

including the systematic selection of fastening tools

To obtain such benefits, it is crucial to select tools thatand their usage, is rarely provided. In recent years, ameet the on-site conditions. Below, we explain the１）certification system for a flange-fastening qualification

important factors for selection.

has been introduced in other countries, and has helped① Fastening-torque value or axial-tension value

to reduce leakage. However, especially in Japan, efforts

When the fastening torque is known, select a tool

to prevent leakage are left to the discretion of facility

which can apply that torque at no more than 70% ofowners and engineering companies.

its maximum output.

Regarding large bolts, which are difficult to fasten by【Point】Consider the tool’s fastening performance.

manpower alone, we sell and rent out tools for such

As a guide, a tool should be selected from tools

bolts. We also offer on-site supervision on shop floors

which have maximum torque output equal to 1.5

where fastening skills vary among the different

times the target torque. If the axial-tension value

operators who perform fastening.

（bolt elongation）is the target value, the tightening

We have accumulated useful knowledge and information

is managed by using a bolt tensioner or a hydraulicabout fastening from on-site experience, and would liketorque wrench & ultrasonic axial force meter as

to share tips on fastening regarding tool selection andshown in Figure1.

considerations for installation.

27

Contribution

nut’s top face, the bolt cannot be fitted with ahexagonal socket. Therefore, center-hole tools andcenter-hole bolt tensioners should be selected.
【Tip】Consider the tool’s operational speed.
Since the operation time per bolt should beshortened, consider selecting a tool with a highFigure1 Measurement‌
of bolt elongation value using an
ultrasonic axial force meter

fastening speed, fastening bolts concurrently
using several tools, and other strategies.

②③‌ Clearance around the target bolt and equipment

Shape and number of bolts and nuts
Since the types of tools that can be used are limited

environment

depending on the shapes of bolts and nuts, such as

Check the clearance around bolts to be tightened

all-screw bolts, tap-end bolts, hexagon headed bolts,

and the equipment environment.

and cap nuts, select tools which match such bolts【Tip】‌Check whether there is space in the axial
direction of bolts.

and nuts.

Large spaces in the axial direction are required【Tip】‌Check whether the selected tool matches thefor pistol-type tools including air torque wrenches.

shapes of bolts and nuts.

On the other hand, hydraulic torque wrenches

When the long part of a bolt protrudes from theTable1Torque range

Booster wrench

Air torque wrench

Hydraulic torque wrench

M16–36

M20–48

M20–56

M30–76

M30 to over M100

1,000–30,000 N・m

Managed using axial
tension（kN）
No scoring on screws
Several screws can befastened concurrently.
Highly-precise fastening
No co-rotation
Troublesome setting
Heavy tool

300–2,000 N・m

500–4,000 N・m

Major
Very strong torque can be Easy cordless operation
characteristics applied with light force. using a pistol-type tool
Advantages

No need for powersourceDisadvantages

Takes time in fastening.

Power source

Unnecessary（Manpower）

Rechargeable battery○×

Explosion-proof
Condition for
application 1
Condition for
application 2

Handy for anyone
High speed
Regular charging isrequired.

Space of at least 250
Space of at least 500
mm is required in themm is required in theaxial direction of a bolt. axial direction of a bolt.
A reaction-force pointshould be secured on the←neighboring bolt or otherarea.

500–6,000 N・m
Easy operation using apistol-type tool
Handy for anyone
High speed
Need for stable air
supplyCompressed air
500 kPa ○Bolt tensioner

Smallest and lightest
among tools with thesame torqueHighly precise torque
Wide torque range
Need for pumps andhydraulic hoses
Compressed air 500 kPa -, Compressed air 500 kPa Power supply 100 V, 200 V○ Depends on pump’s function○

Space of at least 500 Space can be minimal in Space of at least 300
mm is required in thethe axial direction of amm is required in theaxial direction of a bolt.
bolt.
axial direction of a bolt.
Bolt’s head should
protrude from nut’s top←←
face by at least 1d（d:diameter）.

Management method

Input torque wrench

Digital pre-setting

Air pressure

Hydraulic power up to 70 MPa Hydraulic power up to 150 MPa

Concurrent
fastening

N/A

N/A

N/A

（2 bolts to half the
Available（up to 4 bolts） Best
total number of bolts）

Operator No.

1 operator/tool

1 operator/tool

1 operator/tool

1–2 operators/tool

0.5–1 operator/tool

Nut fitting

SocketSocketSocketSocket or direct fitting

Prybar

Speed

☆

☆☆☆☆☆

☆☆☆☆☆

☆☆☆

☆☆

Precision

☆☆

☆☆☆

☆☆☆

☆☆☆☆

☆☆☆☆☆

Operability

☆☆

☆☆☆☆☆

☆☆☆☆☆

☆☆☆☆

☆☆

Lightness

☆☆☆

☆☆☆☆

☆☆☆

☆☆☆☆☆

☆

☆

☆☆☆

☆☆☆

☆☆☆

☆☆

☆☆☆

☆☆☆☆

☆☆☆☆

☆☆☆☆

☆☆

☆☆☆☆☆

☆☆☆

☆☆☆

☆☆

☆☆☆

Concurrent
multiple-bolt
fastening
Applicability tovarious sizes
Introduction cost

28

Winter 2018

Applicable bolt

Characteristics and evaluation of each tool

Battery-type
torque wrench

No.34

Considerations for Tool Selection and Installation of Fastening Bolts for Flanges with Large Nominal Diameters

are compact and can be widely used. Care should

maintenance condition, so maintenance is very

be taken, if space is tight, such as under piping

important, which includes the following:

elbows.

①

Removing rust and scale②

Repairing damaged screw threads③‌Applying lubricant to the nut seat and threaded【Tip】‌Check the orientation in which tools areapplied.

portionWhen tools are heavy, especially when used fromunderneath, workability is greatly affected by thetool’s weight, so the tool’s weight is an important④④‌Smoothing the flange’s surface（when impossible,
use a washer）

factor. When a tool weighing over 10 kg is used

We have checked the maintenance conditions at many

upwardly from underneath, some measure tosites and found that although 1）and 2）are conductedsupport the tool or prevent it from falling isproperly, 3）is often inadequate. In the case of torquenecessary.

control, the axial-tension value of the nut seat surface,

Available power source

which is greatly affected by friction, varies

Check the type of power source available.

significantly when a lubricant is applied to the surface.

【Tip】‌Secure a power supply of 200 V or stable

When the surface condition of a flange is poor,

compressed air.

inserting a washer may improve the condition. We

Winter 2018

If there is no power supply, a booster wrench or ahave seen many such cases.

battery-type torque wrench should be selected

In the case of the all-screw bolt, when lubricant is not（the wrench should be charged）. Also, bolt

applied to the fastening side and opposite side of thetensioners can be pressurized using a hand pump.

nut seat surface, co-rotation is less likely to occur.

By considering the above factors and comparing

No.34

them with each tool’s characteristics as shown in3-2）Fastening procedures

Table1, the candidate tool types can be identified.

When fastening a flange’s bolts while uniformly

Especially, the bolt tensioner uses a different

compressing the gasket, fastening should be conducted

fastening mechanism from the torque method: thein a stepwise fashion, as described in JIS B2251２） andbolt tensioner applies axial force to a bolt by

JPI-8R-15.３）

directly pulling the bolt. Therefore, the bolt

In practice, these standards are rarely observed, andtensioner is rarely affected by the friction

they show procedures only when using one tool for

coefficient of the contact surface, and so offers

fastening. The proper procedures vary depending on

highly accurate fastening and does not scratch

the number of tools used, so it is desirable to set

the flange’s surface. However, many devices aredesigned without assuming that the bolts are
fastened using a bolt tensioner; in some cases,
part of the device must be remodeled, includingchanging the bolts, in order to use a bolt
tensioner in existing facilities.

3. Considerations of assembly3-1）Maintenance of bolts and nuts
The next important factor is maintenance of bolts andnuts. Especially, in the case of torque fastening, theaxial tension applied to bolts varies depending on the29

Figure2 Parallel fastening using two hydraulic torque wrenches

Contribution

efficient procedures which are tailored to the numberof tools used.
Among the proper procedures, we especially
recommend parallel fastening as shown in Figure2. In
parallel fastening, at least two tools are placed
diagonally for fastening.
This requires less work for one bolt until fastening iscompleted in a shorter time period, and the gasket iscompressed evenly. Therefore, this fastening method
can prevent malfunctions resulting from unevenfastening. Valqua’s Seal Training Center４） has facilities

Figure3

where you can experience parallel fastening of flanges

Backup wrenchwith large nominal diameters, so we encourage you tobackup wrenches are not used, co-rotation must be

take advantage of these facilities.

prevented by using slogging wrenches and chisels,
but it takes longer to remove the wrenches thanwhen fastening nuts.

3-3）Considerations on reaction-force point
In torque fastening, in principle tools should apply②

Hydraulic pump with large discharge volume
The speed of the hydraulic torque wrench and bolt

reaction-force point directly results in accuratetensioner depends on the pump’s discharge volume;

fastening force and safety. Therefore, the following

the discharge volume makes a significant difference

procedures are important when fastening nuts: 1）

especially when a large tool is used. However, large

Draw a horizontal line extended from the center oftools are less portable. Therefore, take on-site

the nut to be fastened. 2）On the horizontal extended

conditions into account when selecting appropriateline, set a position where a reaction-force arm is fixed.

tools.

3）Tightly secure the reaction-point arms on the③

Not-too-long hydraulic hose

position in such a manner that the arm is securely

If the hydraulic hose is too long, it is obstructive on

fixed to the position when force is applied to the arm.

the scaffold, and makes tools not only cumbersome
but also slower. The standard length is 5m.

Regarding common flanges, reaction-force points canusually be secured by using the neighboring nut.

④

Nut splitter

However, in other cases, it is necessary to carefully

Figure4 shows a hydraulic nut splitter. Although

check in advance whether a reaction-force point canthis phenomenon occurs only when a nut is

be correctly secured.
3-4）Efficient operation
After tool selection, the actual work will start; a little
preparation in advance can reduce the working time,
so we recommend preparing the following items.
①

Backup wrench
Figure3 shows some backup wrenches. A backup
wrench is set on the nuts on the fastening side andon the opposite side to prevent co-rotation. In
addition, backup wrenches can be removed easily. If

Figure4

Nut splitter
30

Winter 2018

force from a reaction-force point. Securing a stable

No.34

Considerations for Tool Selection and Installation of Fastening Bolts for Flanges with Large Nominal Diametersloosened, if the nut adheres to a bolt too strongly theof many flanges did not function as intended.

nut does not rotate. In this case, hydraulic power canValqua offers various services at its Seal Training

be used to cut a nut quickly to remove a bolt.

Center, to provide proper knowledge and significantly
reduce the risks stemming from users’ignorance.

4. Conclusion

Leakage at the bolted flange joint is mainly due topoor assembly, which may be due to bolt-tightening

This article introduced considerations for tool selection

problems. We offer products and services for bolt-

and installation when fastening the bolts of flanges

tightening, to accumulate on-site experience whichwith large nominal diameters.

cannot be gained from studying theories, and provide

Our first priority is to resolve on-site problems anduseful information for those who need it, ranging fromchallenges in bolt-fastening operations. To achieve thisdesigners to operators. To achieve this goal, we aregoal, we have developed products which are useful on

establishing a system and offering support for all

shop floors; selected tools which meet theprocedures ranging from seal selection to bolt

requirements of each shop floor and promptly

tightening.

procured these tools; created on-site guidance on
handling; and performed fastening management using
an ultrasonic axial force meter.

Winter 2018

Through these experiences, we have encountered１）‌T. Kikuchi and Y. Kondo,“Management Standard

many cases in which ignoring small details resulted in

for Fastening Flanges/Bolts”, The Piping

problems. Two decades ago, there were many skilledworkers and we witnessed their excellent hammering
works. However, when an ultrasonic axial force meter
was used to measure the fastening conditions of thebolts which they had fastened, the meter showed that

No.34

5. References

the bolts had been fastened too strongly. Overfastening was probably performed because the gaskets

Shinichi Kitahara
TORQUE SYSTEM Co.,Ltd.
Managing Director

31

Engineering, November 2017.
２）‌JIS B 2251,“Flange Joint Assembly Guidelines”（2008）.
３）‌Management Standard for Fastening Flanges/Bolts,
JPI-8R-15-2013.
４）‌A. Muramatsu, Valqua Technology News: No. 33,
15–18（2017）.

Business Introduction

H&S Demonstration Car

1. Renewed demonstration car
We set one of our goals—becoming an H&S company—
based on our core principle of“maximizing customer
value.”As an H&S company, we aim to provide not
only seal products（hardware）but also overall sealengineering.
As part of our efforts, in 2014 we opened a Seal
Training Center（STC）, which is a hands-on training
training services. To promote the value andeffectiveness of the STC, in 2015 we started using an

Figure1

H&S Demonstration Car

2. Concept

STC demonstration car, which is fitted with STC

The concept of the H&S demonstration car is not only

training equipment. This car enables simple hands-on

to attract attendees to the STC training sessions but

demonstrations to be conducted at a customer’salso to visually and physically promote the value ofpremises.

the H&S solutions. To do this, we installed part of ourSuch approaches are greatly appreciated by many

service packages, which we newly developed andcustomers, and are highly evaluated by plant owners

started using in relation to our H&S solutions

as well as engineers. The number of STC training

centering on seal engineering, on the car and gave

sessions continues to rise year by year, and we arecustomers the opportunity to try out these solutions.

honored and humbled to receive such positive

In addition, the full-scale renewal allowed us tofeedback.

promote the values of the new H&S service package

During the two years of its operation, the STC

to customers, for whom we had performed work anddemonstration car has helped to achieve one of ourgiven demonstrations in the past.

goals, which is to promote the value of the STC.
Accordingly, we have completely renewed the STC
demonstration car to create an“H&S demonstration
car,”and started using it in autumn 2017 to increase

3. Outline‌of equipment installedon the demonstration car

advertising and promote various H&S service3-1）Mobile Seal Training System（MSTS）

packages.

Mobile Seal Training System（MSTS）is a service
package which integrates both equipment andlecturer-training services. In MSTS, some of STC’s
training facilities are installed on the car to make amobile/assembly type training facility, which allows
32

Winter 2018

center for sealing work, and have since been offering

No.34

H&S Demonstration Car

customers by themselves to give seal training to on-

including hydraulic wrenches and bolt tensioners, aresite operators at their sites.

exhibited.

In addition, the demonstration car features training
equipment for flange tightening and training3-3）Rust-proofing service

equipment to acquire a sense of torque, which are

Various plants and ships & vessels are located andespecially appealing. With this equipment, operators

operated mainly in coastal areas of Japan to facilitate

have the chance to experience training.

distribution. Coastal areas are convenient for
distribution, but involve the challenges of salt damage（equipment rusting）to the devices and piping ofplants and ship & vessels.
To help solve these challenges, mainly rust-proofing
painting is applied. However, such painting involves
various issues regarding life cycle, application period,
smartification, and other challenges. Therefore, newrust-proofing technologies are needed.
Commonly-used rust-proofing paints have poor
adhesion. Therefore, if a gap or space develops

Figure2

Winter 2018
No.34

Mobile Seal Training System（MSTS）

between equipment and paint, it leads to separation,requiring re-painting every 2 to 3 years. When re-3-2）Flange Solution Tool

painting, scraping to remove the degraded coating

To ensure robust sealing, it is important to select notfilm is also required. Therefore, in plants which need

only optimal seals but also optimal operation

to avoid combustion risk, operations should bemanagement. When the positional relation of different

conducted within a limited period during shutdown.

piping flanges is not optimal, correction is dangerous

However, re-painting requires many procedures suchand requires many workers and much time.

as drying.

Accordingly, we started to offer Flange Solution Tool,

A rust-proofing management service using a special

which allow these operations to be executed safely

rust-proofing resin material can resolve these problems.

and efficiently.

The material has the following characteristics:

On the demonstration car, a large demonstration
flange unit is installed. This unit is used for①

fluid.

demonstrations on how to adjust the misalignment ofa flange. In addition, actual bolt-fastening tools

Long-term anticorrosion・‌Oil exuding from within resin blocks oxygen and・‌Since the exudation period is long, long-acting
blocking is expected.
②‌Paint application is possible during plant operation

・‌Unlike common paints, no scraping using tools isneeded.
・Painting can be conducted even on areas where
scraping cannot be performed（painting cannot
be performed）.
③

Excellent post-painting workability・‌Since the special rust-proofing resin material canbe cut with a cutter, overhaul inspection is
Figure333

Flange Solution Tool

simple.

Business Introduction

The demonstration car contains a special rust-proofing
operation unit. This unit is used to demonstrate the4. Conclusion

application of special rust-proofing resin, highlighting theThis report introduced an H&S demonstration car,differences from conventional painting.

which aims to improve the advertising and appeal of
H&S solutions. We will revise the range of equipment
installed on the car in turn depending on thecustomers’ needs, status of new development, andhandling. We dispatch the car all over Japan to help
our customers.

Hajime Nonogaki
Ｈ＆Ｓ Business Group
Figure4

Special rust-proofing operation unit

Winter 2018

Pre-treatment

No.34

Post-treatment

Figure5

A case of rust-proofing treatment
34

Improved Seal Paste

1. Introduction
When seal paste is applied to gaskets, the scratches in

3. Characteristics①

The product does not contain crystalline silica,

flanges are filled with the paste, improving the sealing

which is carcinogenic, nor organic solvent

properties. Therefore, seal paste has long been used

including highly hazardous dichloromethane andfor gasket connection.

toluene. The product is safe and environment-

Although there are no problems with the conventional

friendly.

seal paste, user demands for safety and theenvironment are getting stronger, so we developed an

Winter 2018
No.34

②

improved seal paste.

Since the product contains a solvent with a highflash point, it is categorized as a non-hazardous
material（combustible solids under the designated

2. Product summary
The improved seal paste is a light brown paste based

combustibles*）.
③

The new product has similar properties to theon a special, non-drying, oil-based bond formulated

conventional seal paste. When applied to gaskets,with inorganic filler and a small amount of solvent.

it works as a sealing adjunct, protects the flanges

The formulation is an improvement over thefrom rusting, and prevents gaskets from adhering

conventional seal paste, as it contains no carcinogenic

to the flanges.

substances. In addition, it is categorized as a nonhazardous material under the Fire Service Act. Thus,
the product is safer and more environment-friendly.

④

A brush is attached to the cap, making it easy toapply to gaskets and other objects.

Note : C ombustible solids under the designatedcombustibles: Products whose speed of
combustion expansion is fast in the case of fire,or whose combustion is difficult to suppress.
Petroleum asphalt and some other products fall
into this category. When the amount of such a
product exceeds a designated amount（ 3,000kg）, it is categorized as a combustible solid
under the designated combustibles; when usedor stored in amounts lower than 3,000 kg, it iscategorized as a non-hazardous material.
Figure 1
35

Improved seal paste

Product introduction

4. Applicable fluid
Conventional seal paste

The improved seal paste is applicable to water, air,

Improved seal paste

gasoline, kerosene, lubricating oil, natural gas, LPG,
used when hydrocarbons including ethylene, butane,and ethane are handled, and helps prevent deposit
corrosion on the surface of stainless-steel flanges.

Leak rate

cold water, and hydrogen sulfide. The paste can be

Lower leakage detection limit

5. Service temperature range

Gasket stress

Figure2 Test results of checking the sealing properties at room temperature−50 to 300ºC

Table2

Test conditions for checking compression fracture
Gasket

6. Product form

Gasket dimensions

730 g of paste in a capped metal can with a brush

No.6500
φ100×φ64

t=3mm

Gasket stress

70、100MPa

Amount of paste applied

Approximately 1.75 g on both sides

7-2）Test‌to check resistance to compression fracture

7. Performance dataapplied to gaskets to which either the improved seal

improved seal paste has properties equivalent to thosepaste or the conventional seal paste was applied, toof the conventional seal paste.

evaluate the contact pressure at which compression
fracture occurs.

7-1）‌Test to check sealing properties at room
temperature

No abnormalities occurred at contact pressures of up
to 70 MPa, neither with the improved seal paste nor

To evaluate the sealing properties of each paste,with the conventional seal paste. Compression fracture

various low contact pressures were applied to gaskets

occurred at a contact pressure of 100 MPa with bothto which the improved seal paste or the conventional

pastes, verifying that the two pastes have equivalentseal paste was applied. As a result, leakage fromproperties. Figures 3 and 4 show enlarged photos ofgaskets using the improved seal paste stopped at acontact pressure of 7.5 MPa, the same as leakage fromgaskets using the conventional seal paste. This result
demonstrates that the improved seal paste has
properties equivalent to or better than those of theconventional seal paste.
Table1 Test‌
conditions for checking the sealing properties atroom temperature
GasketGasket dimensions

No.GF300
JIS

10K

50A

t=1.5mm

Fluid

Nitrogen gas, 3.5 MPa

Gasket stress5、7.5MPa
Improved seal paste
Conventional seal paste

Type of paste
Amount of paste applied

Approximately 0.7 g on both sides

Winter 2018

Contact pressures of 70 MPa and 100 MPa wereThese performance data demonstrate that the

Figure 3 Compression-fracture‌
test of conventional seal paste
Compression fracture was confirmed at 100 MPa.
36

No.34

Improved Seal Paste

8. Conclusion
Since legal regulations on toxic substances anddangerous substances are becoming stricter due tosocial demands regarding safety and the environment,
customers increasingly need products that meet suchsocial requests. Accordingly, we will continue todevelop safe and environment-friendly products forusers.

Figure 4 Compression-fracture‌
test of improved seal paste
Compression fracture was confirmed at 100 MPa.

gaskets which suffered compression fracture.

Winter 2018
No.34

37

Masato Hamade
Corporate Research andDevelopment Group
Product Development DivisionⅠ

Product introduction

Multi-Purpose Gland Packing for
Chemical Applications
1. Introduction
To date, various types of carbon-fiber products, whichhave heat and chemical resistance, have been used as
gland packings for chemical applications. However, for aparticular product, different types of packing should be
used depending on how the product is used. When
PTFE dispersion, graphite
particulate, lubricating oil

several types of packing are taken from stock and used,
there is a risk that the wrong type of packing might beincurring safety risks.

Figure1

Winter 2018

Carbon fiber

used, possibly causing damage to plant operation andOutline illustration of No. 6137 series

We have developed a new product based on carbon
fiber like the conventional product, but when used in asingle product, different types of packing are notrequired depending on how the single product is used.
The new product can also be used under diverse

No.34

conditions in a single product, and offers the same heat,pressure and chemical resistance. Therefore, the new
packing improves the stability and safety of operation,and helps reduce inventory.

2. Composition
No. 6137 series is based on gland packing manufactured
as follows:（1）Carbon fiber is treated with PTFE

Figure2External view of No. 6137 series

3. Characteristics

dispersion.（2）The cross section of the treated carbon① No. 6137 series is suitable for a wide range offiber is braided into a square shape.（3）The shaped

applications, including valves, pumps, equipment,

carbon fiber is finished with PTFE dispersion andand others.

graphite particulate. Both oil-containing and oil-free② The main materials of No. 6137 series are carbon

types are available. The three types, No. 6137, No. 6137-

fiber and PTFE dispersion, which have excellent

O, No. 6137-SO, can be selected depending on thechemical resistance. Therefore, No. 6137 series canapplication.

be used for most fluids except strongly oxidizing
fluids.
③ No. 6137 series is suitable for a wide range of38

Multi-Purpose Gland Packing for Chemical Applications

applications, resulting in excellent cost performance（inventory reduction）.

6. Specifications
Nominal dimension: □ 3.0–25.0 mm
Packing unit: 3 m（Ring-shape molding is also available.）

4. Applications
・Common applications of No. 6137 series
N o. 6137 series can be used for valves, pumps,

7. Results of functional tests

packings of seal devices, etc., all of which handle

7-1）Evaluation of basic characteristics

chemical fluids（except for oxidizing acids andBasic-characteristics tests are conducted to evaluateoxidizing agents including concentrated sulfuric acidcompressive-strain characteristics, sliding characteristics,

and concentrated nitric acid）.

sealing characteristics in valves, and use as glandpacking.

・‌No. 6137 can be used in valves and devices forapplications designated as oil-free processing, requiring

Test conditions:
Table2no contamination by lubricating-oil, and for prevent
softening and loosening of the packing due tolubricating-oil reduction.
・‌No. 6137-O can be used for valves and devices as well

Winter 2018as high-speed pumps including turbo pumps, all of

No.6137-O，No.6232（1）Refer to“Figure 3. Outline illustration of
Test equipment
basic-characteristics test equipment.”
Evaluation of basic characteristics
Packing dimension φ20×φ33×6.5H

It can also be used as a substitute for No. 6232 and No.

Packing qty
Stem radial
clearance
Packing stress6262（thus reducing inventory through part-number

Fluid

Nitrogen gas

Fluid pressure

1.0 ～ 9.8 MPa

which require low torque and gas-sealing performance.

integration）.
・‌No. 6137-SO can be used for high-speed pumps such as

No.34

Gland packing

Test conditions

turbo pumps, which need greater heat resistance than

6 rings
0.5mm
4.9 ～ 58.8 MPa

Note（1）: No. 6232 is used for valves and reciprocating equipment.

Outline of the test method:

No. 6137-O in devices which require low torque and①

Mount the gland packing in a test jig.

gas-sealing performance.

②

F asten the packing under a given contactpressure using a compression tester.

③ Measure the height and stem torque of the packing.

5. Usable range
Table1
Application
Maximum service
temperature
Maximum
service pressure
ANSI rating
Maximum
service speed
PV tolerance
pH range④

Product specifications

Valve

Pump

the leak rate.
Device260 ℃
15.5 MPa

1.6MPa⑤

I ncrease the packing

stress in a stepwise

fashion, and repeat steps ② to ④ .
9.8MPaClass 900―――

20m/s（1）5m/s（1）―

14.7MPa･m/s（1）―0 〜 14Note（1）: ‌Maximum service speed and PV tolerance are applicable toNo. 6137-O and No. 6137-SO.

39

Load fluid pressure on the packing and measure

At start
During sliding
At start
During sliding

Simplified μK value

Compression tester

Stem

Gland

Fluid pressure（MPa）

Product introduction

Packing stress（MPa）

Packing stress（MPa）

Figure6 Sliding characteristics（μk value） Figure7

Sealing properties

7-2）Reciprocation-tolerance test
Gland packing

Reciprocation-tolerance tests are conducted toevaluate the sliding-resistance characteristics andsealing characteristics against reciprocating motions of
the gland packing for valves.
Table3Pressure port

Test conditions

Gland packing No.6137-O，No.6232（１）Refer to“Figure 9. Outline illustration of a
Test equipment
reciprocation-tolerance tester.”
Packing dimension φ20×φ33×6.5H
Packing qty

Figure3 Outline illustration of basic-characteristics test equipment

The results of the basic-characteristics evaluation are
shown in Figures 4 to 7.
No. 6137-O had a slightly lower compression ratio,
weaker stem resistance, which is a sliding characteristic,
and improved performance than the conventional
product No. 6232. Regarding sealing properties, bothFigure4 Compression characteristics

Stem resistance per unit contact-surface area（N/mm2 ）Compression ratio（％）

specimens showed equivalent results.

Packing stress（MPa）

Packingarrangement
Fluid

Test results:

8 rings（2 rings + lantern ring + 6 rings）
×2

Water and heated water

Test temperature 260℃
Stem radial
0.7 mm（inner diameter = φ21.4）
clearance
Sliding number 1000 reciprocations × 3 cycles（3000 reciprocations）
Initial packing stress: 39.2 MPa
Additional packing stress: 39.2 MPa
Stem stroke: 50 mm
Stem operating
Stem speed: 25 mm/sec
conditions
Stem stop: 1 sec
On heating: 10.2 MPa
Fluid pressure When withstanding pressure at room temperature:
11.0 MPa
Packing stress

Note（1）: No. 6232 is used for valves and reciprocating equipment.
At start
During sliding
At start
During sliding

Test results:
Figure 10 shows the results of the reciprocationtolerance tests.
No. 6137-O had a weaker stem resistance, which is a

Packing stress（MPa）

Figure5 Sliding characteristics

sliding characteristic, and improved performance thanthe conventional product No. 6232. Regarding sealing
properties, both specimens showed equivalent results.

40

Winter 2018

Compression（loading packing stress）

No.34

Multi-Purpose Gland Packing for Chemical Applications

At 260ºC at the time ofpartial heating
When withstanding pressure
at room temperature

Pressure

Staffing box on thefollowing side
Load cell（measuringcontact pressure of
packing）

Staffing box on thedriving side

Band heater

Pressure port
Gland
Leak-off

Load cell（measuringstem resistance）

Stem

1000
reciprocations

Fluid temperature（℃）

Figure8

1000
reciprocations

1000
reciprocations

Figure9 Outline illustration of a reciprocation-tolerance tester

Outline of test cycles

1000 reciprocations

1000 reciprocations

1000 reciprocations

At start
During sliding
At start
During sliding

Leak rate（cc/h）

following side
driving side
following side7-3）Large-bore pressure test

At coolingAt the time of temperature rise

At cooling

Results of reciprocation-tolerance tests

At room temperature

At the time of temperature rise

Figure10

At room temperature

At the time of temperature rise

Tightening

No.34

At cooling
Tightening

driving sideAt room temperature

Winter 2018

Stem resistance（kN）

Hydraulic cylinder
Lantern ringfor driving
Gland packing
Gland packing（below lantern）（above lantern）

Outline of the test method:

Large-bore pressure tests are conducted to evaluate①

Mount the gland packing in a test jig.

the pressure tightness of a gland packing.

②‌Use a torque wrench to tighten the gland packing
to a given packing stress.

Table4

Test conditions

No.6137-O
Refer to“Figure 11. Outline illustration of
Test equipment
large-bore pressure tester.”
Packing dimension φ80×φ112×16.0H③

Gland packing

Packing qty

using a water-pressure booster.
④

packing or leaks.

Stem radial clearance 1.2 mm（inner diameter = φ82.3）
39.2 MPa

Temperature

Room temperature

Fluid
Fluid pressure

41

Water
15.5 MPa, 19.4 MPa, 23.3 MPa（Maximum, ANSI Class 900 × 1.5）

‌After keeping the pressure for 30 minutes,
check whether the fluid penetrates through the

6 rings

Packing stress‌Apply a given fluid pressure to the sample⑤‌ncrease the fluid pressure in a stepwise fashion,
and repeat the check of step ④ .

Product introduction

equipment. Through the alternate switching, theperipheral speed and discharge pressure are varied,

Stem
Packing presser
Gland packing

creating much more severe conditions than underregular operation. Under such conditions, the leak rateand stem-torque characteristics were evaluated.

Stop
Pressure port

Figure11

Outline illustration of a large-bore pressure tester

Test results:
Table 5 shows the results of the large-bore pressure

Figure12

Inverter activation cycle

Test pump : General-purpose, single-suction centrifugal pumpMotor
: 4-phase, 200 V（60 Hz）, 4 poles, 5.5 kW
Pump bore : 65 × 50
① : Test pump
② : Pump for pressing pressure

test.
Pressure tightness was improved from the diameter

Thermometer

6232; No. 6137-O can be used at the diameter of up to

Valve for discharge-pressureadjustment

ANSI Class 900.
Table5Results of large-bore pressure tests

Fluid pressure（MPa）

19.4

23.3

ANSI rating

Class 900 × 1.25

Class 900 × 1.5

Penetrating

None

None

Leakage

None

None

Figure13 Outline illustration of a long-term inverter-tolerance tester

Test results:
Tables 7 and Figure 14 show the results of theinverter-tolerance tests.

7-4）‌Test to evaluate long-term durability

In the tests, varying pressures and peripheral speeds

against inverter using an actual

were applied to the samples through inverter

equipment pump

operation of a rotary pump of actual equipment.

In inverter-tolerance tests, the rotation of a rotary

Under varying pressures and peripheral speeds, No.

pump’s motor is switched alternatingly between 60

6137-O showed stable tolerance and had equivalent

Hz and 30 Hz using an inverter in the pump of actual

leak rate and sliding resistance to the conventional

Table6

product No. 6262.

Test conditions

Test equipment

Refer to“Figure 13. Outline illustration of along-term inverter-tolerance tester.”Gland packing

No.6137-O，No.6262（１）Packing dimensionＨ
φ35×φ51×8（4rings）

Fluid

Water

Temperature

Course of events

Pushing pressure

0.5MPaTest frequency

60Hz

30Hz

Rotation

1800rpm

900rpmPeripheral speed

3.30m ／ s

1.65m ／ s

Discharge pressure

0.8MPa0.6MPaPV value

2.64MPa・m ／ s

0.99 MPa・m ／ s

Winter 2018of ANSI Class 600 for the conventional product No.

Pressure 1：Pressing pressuregauge
2：Discharge pressure

Water tank

Table7

Results of inverter tests

Operation time
Fluid temperature（1）Gland packing
Frequency
Minimum value
Leak rate（２）Maximum value（cc/min）
Average

Approximately 1000 hours
Course of events
No.6137-O
No.6262（３）
60Hz
30Hz
60Hz
30Hz
6
6
9
9
18
15
90
90
14
13
26
26

Note（1）: ‌Fluid temperature fluctuates depending on packing’s
frictional heat and piping resistance.
（2）: ‌Leak rate just after inverter activation（3）: ‌Test results do not include time for running-in and initialadjustment.

Note（1）: No. 6262 is used for rotary pumps and rotary devices.

42

No.34

Leak rate

Multi-Purpose Gland Packing for Chemical Applications

Temperature（℃）

Operation time（h）

Winter 2018

Sliding torque（N・m）

Operation time（h）

Operation time（h）

Figure14 Results of inverter tests

8. Conclusion
No.34

inventory management and reducing the risk
associated with product mis-selection.

With the products described here, different types of

We will continue to develop new products to satisfy

products do not need to be selected depending on thethe varying needs of individual users.

application, thus improving the efficiency of the

43

Syuuzi Sugawa

Masato Hamade

Corporate Research andDevelopment Group
Product Development DivisionⅠ

Corporate Research andDevelopment Group
Product Development DivisionⅠ

Recent Technology News Back Issues
No.33 Summer 2017
【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

Sales Group

Evaluation of Basic Sealing Properties of the Pipe

Toshihiko Enishi

Technical Solution Division

Flange Connection with Metallic Flat Gasket

Corporate Research and Development Group Development Division	

SHINKO PLANTECH CO., LTD.

Kouji Satou

Yasuharu Kondou

	Professor Emeritus at the University of Hiroshima	Corporate Research and Development Group

Toshiyuki Sawa

Satomi Takahashi

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

Seal Training Center (STC) –Interactive Training for Sealing Operation

	

Ｈ＆Ｓ BUSINESS GROUP

Akira MuramatsuManagement 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

Winter 2018

● Contribution

Akira Ueda

No.34
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 Nishida44

●Contribution Congratulations on the 90th Anniversary Special Issue of Valqua’s Establishment
Professor Emeritus at the University of Hiroshima Toshiyuki Sawa

●Contribution Evolving Gasketing and Sealing Technologies
Professor at Mechanical Engineering, National Institute of Technology, Numazu College Takashi Kobayashi●Contribution Congratulations on the 90th Anniversary Year of the Founding

NIPPON VALQUA INDUSTRIES, LTD.

Takao Iwane

former Managing Director (Technical Manager)●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)

Yoshiaki Mori●Contribution Memories of My Tenure as CTONIPPON VALQUA INDUSTRIES, LTD. former CTO Hiroyuki Kuroda

●Technical Papers Types and Application of Filler-added PTFE Materials


Corporate Research and Development Group

Development DivisionHigh Performance Plastics Development Division

Youichiro Wada

Winter 2018

●Technical Papers Accuracy and Mold Direction of PTFE Products

Corporate Research and Development Group Development Division High Performance Plastics Development DivisionTechnical

SectionNo.3

Shigeko Kawai

Corporate Research and Development Group Development Division High Performance Plastics Development Division



No.34

ServiceTechnical

Service

SectionNo.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 kenichi Takahashi●Technical Papers Sticking Troubles of O-Rings and CountermeasuresCorporate Research and Development Group

Development Division 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●VALQUA’s Technical History●Recent Technology News Back Issues

45

Development Division Kouji SatouNo.31 Summer 2016
[Customer Solutions Special]●Greeting●Commentary

Customer Solutions and Evaluation Technologies

Senior Excutive Officer

Director of Corporate Research and Development Group Corporate Research and Development Group

Development Division

General Manager

Mutsuo Aoki

Takaharu Ikeda●Technical Papers Gasket Clamping Problems and Their Solutions
Corporate Research and Development Group

Development Division

Takahiro Fujihara

Large Diameter Gland Packing Installation Problem Examples and Installation GuidelinesCorporate Research and Development Group

Development Division

Masato Hamade

Causes of Blister Problems Resulting from High-pressure Gas and Highly Volatile LiquidsCorporate Research and Development Group

Development Division Hirofumi Zushi

Causes of O-ring Transfer Problems and Their Solutions
Corporate Research and Development Group	Lining Pipe Problem Examples

Corporate Research and Development GroupHigh Performance Plastics Development Division

Technical Service Section No.1

Ryosuke Nishi

Development Division

Yoshifumi Kutsuzawa

Corporate Research and Development GroupHigh Performance Plastics Development Division

Development

Technical Service Section No.3 Nobuyuki Ota●Contribution	Characteristics of Hydraulic Cylinders Used in Standard Industrial Machinery and
Their Seal System Problems―Responding to the MRO Market
Winter 2018

Explaining the PTFE Linear Coefficient of Expansion
Division

Development Division

TAIYO,LTD. Toshinori Ueda

No.34

46

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.34 Winter 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
GARLOCK VALQUA JAPAN, INC.
TEL : (81)3‑5510‑2177 FAX : (81)3‑3591‑5377■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(THAILAND), LTD.
SINGAPORE BRANCHTEL : (65)6352‑2650
FAX : (65)6352‑2653■THAILANDVALQUA INDUSTRIES(THAILAND), LTD.
【Head Oﬃce】
TEL : (66)2‑324‑0400 FAX : (66)2‑324‑0787【Bangkok Branch】TEL : (66)2069‑9961
FAX : (66)2069‑9964【Rayong Branch】 TEL : (66)3802‑6136
FAX : (66)3802‑6137■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)220‑357‑0075 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.