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

Practical training Equipment for Flange
Tightening Force Fluctuation due toTemperature Difference
1. Introduction

internal fluid through practical training and to know
the mechanism. We asked Valqua Co., Ltd. to

A countless number of flanges are used in petroleum

manufacture practical training equipment and develop

refineries to connect pipes. Because there is littlea training program using that equipment.

leakage of internal fluid from these flange connection

In this paper, we are going to report the summary ofparts, the plants are operated with little awareness ofthe practical training program by using this equipment.

leakage of internal fluid from the flange. In addition,although we know as general knowledge that metalmaterials expand and contract due to temperature

2. Overview‌of practical training equipment
2-1）Design specification

largely determine whether or not the operation is

In examining the specifications of the practical training

performed in relation to the flange tightening force.

equipment, we adopted a fluid temperature（highAlthough veteran employees recognize that flanges

temperature, low temperature）close to our case, andleak from past failure experiences, young employees

considered safety for use as training. The equipmentwith little experience cannot imagine that leaks will

was designed based on the training program, and both

occur from the flange connecting parts.

companies discussed the design proposal, and theIt is essential a the safe operation of the plant to learn

equipment which reflected the result of the consultationthat when a piping changes in temperature, the flange

was produced.

tightening force is affected, and in some cases, theinternal fluid leaks from the decrease in the surface2-2）Outline of equipmenttpressure, and this knowledge must be learnt by theOutline of the completed equipment is shown inpersonnel involved in the operation of a plant.

Figure1. The central part is a flange for monitoring theAt this refinery, there have been past cases where

flange tightening force, and the tightening force offlushing oil（light oil）leaked from the flange fastening
part during the start-up operation. Leakage occurs
when flushing oil（about 25 ℃）is introduced, a sudden
temperature drop occurs at the connected hot pipe
flange connection（about 200 ℃）, the surface pressure
at the pipe flange connection decreases due to thechange in the pipe’s thermal strain.
From the above discussion, it is indispensable for safe
operation of the plant to learn the decrease in surfacepressure of the flange connecting part due totemperature change and the subsequent leakage ofFigure1 Educational hands-on training equipment（The left side is the high temperature part, the right side is the low temperature part）
8

Winter 2019changes, it seems that knowledge and experience

No.36

Practical training Equipment for Flange Tightening Force Fluctuation due to Temperature Differenceeach bolt is displayed on the monitor on the left handdepartment because the gasket replacement anddesk.

tightening of small-diameter pipes are carried out by
the trainees themselves.）2-3）Training procedures（see Figure2）① Set the fluid temperature on the high temperature3-1）Manufacturing Department

side to about 200 ℃ , monitor the flange tightening

Lecture program 1.5 hours（see Figure 3）

force online without the fluid on the low temperature・What is a gasket?

side（about 20 ℃）, and check the tightening status（What is a seal /allowable leakage /（balance）on the monitor.
② Introduce the low-temperature side fluid gradually,required characteristics, etc.）
・Type of gasket and Tightening

and visually check the level inside the pipe from the（Tightening method/retightening, etc.）

peephole（right flange in Figure1）.

・Failure cases③ Check how the flange tightening force（balance）（Poor tightening, selection mistakes, etc.）

changes by adding low-temperature fluid.
④ Through this experience, each person will experience a
decrease in flange tightening force that leads toleakage of internal fluid, and each person should
be careful when operating the plant equipment in

Winter 2019

charge.

Figure3No.36

Trainees attending a lecture programPractical training program 4.5 hours（see Figures4, 5and 6）
・Flange tightening methods for gaskets（‌Compare the tightening force actually tightenedby each trainee against the target tightening
Figure2 emonstration of practical training program byD
using new equipment
（Trainee in the front and lecturer in the back）

3. Training program
We asked STC Nara to install this practical training

force, and determine their own skill.）・‌Gasket creep relaxation, sealing performance,
compression failure（‌Experience of defects due to creep phenomenon,
which are the thermal characteristic of gaskets,
excessive or insufficient tightening force.）

equipment and consider a training program that

・Influence of bolt management

combines this training with the existing equipment

・Practical training using new equipment

and training program related to flange tightening. The（mentioned above）

training program is different for the manufacturing
department and the construction department.（Themanufacturing department allocates about one hourmore for tightening flanges than the construction
9C u s t o m e r S o l u t i o n s《 C o n t r i b u t i o n 》

Practical training program 3.5 hours
・Fange tightening methods for gaskets
・Gasket creep relaxation, sealing performance
・Influence of bolt management
・Practical training using new equipment（mentioned above）
The training is conducted in small groups of four inorder to reinforce the lecture program with thepractical training program, and to enable eachparticipant to think about and experience the purpose
Figure4 emonstration of practical training program
Dby using existing equipment（Torque checker）

of practical training, and to fully understand theresults. The participants are engaged in practicaltraining with a sense of tension. In addition, althoughsafety measures have been taken into consideration inadvance, it is also intended that a small number ofpeople will maintain a sense of tension and prevent
accidental injuries.
and it takes about 2 hours one way from our company
in Yokkaichi to Nara Pref.（Valqua）, and the work load
for shift workers is particularly heavy. For this reason,
lecture programs are held multiple time at Yokkaichi

Winter 2019

The standard training hours are from 9:00 to 17：00,City（our company）, and practical training programs
Figure5 D emonstration of practical training program by using
existing equipment（Flange tightening equipment）

are performed at Nara STC（Valqua）
.

No.36

4. Results of training
At the end of the training, VALQUA, Ltd. conducts asurvey and the feedback from the participants isused in subsequent courses.
To summarize the results of our 12 participants' so far① Overall satisfaction：Average 4.7（5 levels of satisfaction high 5 ⇔ low 1）② Difference between initial expectation and actualcontent：Average 4.8（5 levels of expectation as expected 5 ⇔ disappointing 1）
Figure6 D emonstration of practical training program by using
existing equipment（Seal performance equipment）

3-2）Construction Department③ Understanding of lecture program：Average 4.3（5 levels of understanding well understood 5 ⇔ notunderstood 1）

Lecture program 2.5 hours④ Understanding of practical training program：Average 4.7

・What is a gasket?

（5 levels of understanding well understood 5 ⇔ not・Gasket types, selection, and tightening

understood 1）
10Practical training Equipment for Flange Tightening Force Fluctuation due to Temperature Difference

The average understanding level of the practicalsurface pressure at the pipe flange connection may

training program is 4.7, which is a high level ofcause a leakage of the internal fluid which may lead tounderstanding.

a major accident. On the other hand, even if you are in

Comments from the participants

charge of the operation and maintenance of a refinery,“I was surprised at the faster change in tightening

you rarely have the opportunity to actually experience

force due to flange quenching than expected.”

the mechanism of surface pressure reduction, and in“It was easy to understand because we were able tomany cases when trouble occurs you are reminded ofconfirm the decrease in tightening force due to coolingits importance.

in real time.”

In this study, VALQUA, Ltd. developed practical“By experiencing equipment that simulated an actual

training equipment and by developing a practicalcase it reinforced the dangers in me for the next 10, 20

training program with the equipment it teaches theyears or more.”mechanism of reduction of surface pressure at the pipe

It seems that they had a favorable impression of theflange connection part due to temperature-change

practical training equipment.

which causes leakage of internal fluid and this is

Most participants have the impression that they would

essential to the safe operation of the plant.

Winter 2019like to introduce this training to their colleagues

As a result of conducting employee education using（especially junior colleagues） in the workplace.

the practical training equipment, its effectiveness could

Because of the high level of satisfaction andbe verified, so we will continue to educate employees

understanding mentioned above, it is consideredon the importance of managing flange tightening force

effective in strengthening management of flange

utilising this equipment and the practical training

tightening force by participating in this training, andprogram. In addition, we hope that many otherthe participation of those who have not yet participatedcompanies will take this program to prevent similarin this training is planned as part of our educational

trouble at their factories.

program in the future.

Finally, we would like to thank Valqua, Ltd. and Toyo
Sangyo Co., Ltd., for manufacturing this equipment andNo.36

5. Conclusion

for giving us the opportunity to publish our findings
and experience.

We have installed piping and valve facilities on ourpremises, and as part of our training for newemployees, we have taught them about the importanceof gasket replacement and flange tightening by basic
operations training such as flange tightening as
voluntary maintenance activities. A decrease inKenichi Takamura
Engineering Department
SHOWA YOKKAICHISEKIYU CO.,LTD11

6. Reference1）Akira Muramatsu：Valqua Technology News No. 33,
15-18（2017）