Our engagement with improvement ofquality in workmanship within a commoncertification system for flange fastening
Table1

1. Introduction
For a stable supply of safe and high-quality productAs part of local community through the operation ofyear umber of disasters due to the defects ofN
maintenance control of facilities

Poor
Caused by
Poor
Poor
Poor vessel
corrosionflangeinspection
totalmanagement fastening management inspection management

2018

12195

183413281

appropriately control maintenance of facilities.

20171139329307272

The fluids we deal with are diverse, which can be either

2016109

102204110282

gas, liquid or solid. Some of them are combustible,

2015

9360

311721

222

flammable or explosive, or toxic to human bodies and2014

78

55

191116179

environment. Therefore, we must definitely avoid any

2013

80

56

28

16

20

200

leakage coming from defects of the flange fastener

2012

65

59

65

811208

2011

67

66

66

820

227

petroleum and petrochemical factories, it is essential toWinter 2021

component.
Meanwhile, there are hundreds of thousands of flange

Source：“Summary of accidents related with high pressure gas”
by the Ministry of Economy, Trade and Industry

fastener components in the factory. We aim at early
detection of defects in our daily check, and we must
prevent a leakage disaster in the future with the right
However, in reality, there is a tendency that the numberof disasters and accidents“caused by flange fastening”％

control of tightening at flange fastening.

NumberNo.40

within Japan is increasing. As shown in Table1 and
２０１８

２０１７

２０１６

and proportion, and remain high in recent years.

２０１５30% and more of those. They are increasing by number

２０１４and accidents“caused by flange fastening,”which count

２０１３

been increasing every year. Part of this are disasters

２０１２

to the failure of management control of facilities has

２０１１

Figure1, the total number of disasters and accidents due

Source：“Summary of accidents related with high pressure gas”
by the Ministry of Economy, Trade and Industry

Figure1 N umber and proportion of disasters attributed toflange fastening

We can suggest that“qualification system”andcrane, scaffolding, and oxygen-def icient operations have“industry structure”are the cause of an increase of

official qualification systems and structures in which

troubles arising from flange fastening.

knowledge and skills are gained systematically including

Regarding the former, the problem is that there is noclassroom education and practical lectures. On the otherofficial qualification system for flange fastening and wehand, flange fastening operation is important, but has noare dependent on technical tradition among operators.

official qualification system. In the current situation, it

For example, all dangerous and important work in thecan be practiced by anyone regardless of theirfactories including welding, non-destructive checking,knowledge or skill.

3C u s t o m e r S o l u t i o n s《 J o i n t A u t h o r s h i p 》

Regarding the latter, the problem is that domestic

Mizushima Refinery of ENEOS Holdings has launched

construction workers are decreasing and aging yearly.

“Mizushima Flange Fastening Committee”together with

As you can see in Figure2, the number of construction

nearby refineries on April 1, 2019 and built a common

workers has decreased by around 30% within the last 20

certification system for flange fastening in the area,years. Also, as seen in Figure3, 30% of plumbers are 55

which has been operating with efficiency andyears and older, therefore it is inevitable that those witheffectiveness. Following the education and certifying

more experience who we have depended upon for theirsystem of Mizushima, Kawasaki and Negishi Refineries

knowledge and experience will decrease drastically inalso launched an association of flange fastening in thenear future.

Keihin Area together with Raiznext Corporation andWith all these situations, it is an urgent necessity toValqua, Ltd., to introduce a common certifying system.

build an education system for flange fastening to secure

They have rolled out the common certifying system on asafety especially for young workers, foreign operators

trial basis at the regular repair work（hereinafter,and those working on the spot and to improve“Regular repair”）in the accounting year of 2020 and areoperational quality.

advancing its formulation.

（Ten thousand people）

OthersSales person
Sales manager , Clerical worker
Engineer
Silled worker   Table2

 usiness establishments composing Mizushima
B
Flange Fastening Committee・Mizushima Manufacturing Site, Production Control Division, Asahi
Kasei Corporation

・Mizushima Factory, Mitsubishi Gas Chemical Company, Inc.
（MGC）
・Okayama Office, Mitsubishi Chemical Corporation（MCC）
・Mizushima Refinery, ENEOS Holdings

In this report, we describe the summary, results andvalidation of the effect of the certification system forSource：“Currentsituation of construction industry, construction andbuilding workers”by the Ministry of Land, Infrastructure,
Transport and Tourism

Figure2

Transition of the number of construction workers

Total（Occupational minor classification）
Construction and civil engineering workers
Plumberflange fastening introduced on a trial basis at the regular
repair conducted in March 2020 at Kawasaki Refinery.

2. Summary of certification
system for flange fastening
To improve the quality of flange fastening, what is
important are operators’ skills who fasten flanges andthe knowledge of supervisors who instruct thisoperation. Therefore, the certification system for flange

85 ～80 ～ 84

75 ～ 79

70 ～ 74

65 ～ 69

60 ～ 64

55 ～ 59

50 ～ 54

45 ～ 49

40 ～ 44

35 ～ 3930 ～ 34

25 ～ 29

20 ～ 24

15 ～ 19

fastening we created has two educational parts,“practical education（practical skills）”and“knowledge
education（classroom learning）,”, with unified educational
contents, and we realized a system in which we canSource：“Detailed
sample tabulation of the National Census”byStatistics Bureau of Japan, Ministry of Internal Affairs andCommunications

Figure3

Age group distribution of plumbers

educate with efficiency by standardizing the level ofeducation.
Also, we issue certificates to approved supervisors and4

Winter 2021

・Mizushima Factory, Zeon Corporation

No.40

Our engagement with improvement of quality in workmanship within a common certification system for flange fastening

operators, which allow them to operate flange fastening
in other business establishments just by showing them.
Overlapped education is not necessary which promotes
efficiency.

participants of education for each level.
Table3

Levels for knowledge education in the certification
system for flange fastening

Educationlevel2-1）Practical education（practical skills）
Practical education aims at learning the behavior ofLevel ⅣLevel Ⅲ

Targetposition
Educationlecturer

Education item
HPI TR Z110
"Manager"compliance

4hr

HPI TR Z110
"Worker"compliance

2hr
1hr

flanges when fastening them and understanding theLevel ⅡManagerENEOS standard（classroom lecture + practice training）

operators’ own abilities. Until now, education wasLevel Ⅰ

WorkerENEOS standard（classroom lecture）

acquiring senses through instructions of supervisors

Educationtime

5-20minbased on their experience. Now we can quantitatively
confirm the skill level by having the operators have areal physical experience with the bolting simulator

3. Effect of our engagement（Figure4）. With this simulator, it is possible to evaluate3-1）Summary of system operation

skills quantitatively which used to be evaluated

In November 2019, we have conducted education for

Winter 2021

qualitatively. This simulator uses criteria including

level III at Kawasaki Refinery（number of participants :“enough fastening is given to the gasket,”“strength to17）. Education for Level III is given to be approved as

the fastening shaft of each bolt is even,”and“no sign oflecturers. We gave classroom education with education

uneven crush on gaskets.”

content was based on HPI TR Z110（education time : 2hours）.
Contents of education include“control of fastening
gaskets and bolts as fastener parts,”“setting up andprocedure of fastening load and target torque,”“pressure-resistant airtightness test,”“opening offastener part,”and“trouble examples.”No.40

As practical education（practical skills）, we conducted“training on fastening procedure”in accordance with JIS
B 2251, using the bolting simulator, following a lecture inadvance of practical education regarding interactions ofelasticity, causes of uneven fastening and countermeasures
for it as warnings on flange fastening, and thenevaluated each person’s skill（pass / fail）.
After this, we launched operation of this system on aFigure4

Bolting simulator

trial basis at a regular repair（March 2020）in Kawasaki
Refinery. We gave education for level I to all supervisors2-2）K nowledge education（classroom learning）

and operators engaged in flange operations for works on

For knowledge education, we used educational materials

quiet devices（number of participants：411）. Thiscreated by the Mizushima Flange Fastening Committee,

education was carried out according to the flow asbased on HPITR Z110（Guideline for Flange Fastening

follows by the lecturers who acquired approval of levelOperation Training）issued in September 2018. InIII as given above.

addition, we have set up 4 educational levels（Table3）as

The flow of this education starts with collective

this committee did, to create an efficient educationaleducation（10 to 20 minutes）which explains“behaviors

system by clarifying the educational contents andof flanges at diagonal /circling fastening,”“importance of5

C u s t o m e r S o l u t i o n s《 J o i n t A u t h o r s h i p 》

setting up,”and“description of interactions of elasticity

conduct a proper fastening procedure.

and uneven fastening”. Following this, the skill of eachparticipant was evaluated by using the bolting simulator3-4）Review of effect of educationand judged as pass or fail. We issued certificates to thoseon comprehensive airtightness test

who passed, which will allow them to do flange fastening

At the very final phase of a regular repair, we conduct aoperations on sites.

comprehensive airtightness test by bringing in nitrogen
within the system for the purpose of confirming
soundness of open parts including devices and plumbing

We received good feedback overall from participants offlanges, and the whole equipment. To be precise, welevel III education, including 90% of them replying that it

conduct a soap bubble test to check leakage of nitrogenraised their awareness of flange fastening and 80%

at the open parts including each flange after bringing insaying they can apply the contents of lectures at

nitrogen and pressure rising. If leakage is detected, moreoperations on sites. Also, 60% say they found out

flange fastening is carried out. If leakage cannot besomething new from the contents given to lecturers.

halted despite of that, we decrease the pressure ofTherefore, it was also found effective as an opportunity

nitrogen in the system and conduct the pressure rising

to learn again.

test again upon re - opening flanges, maintaining surfaces

Seventy percent of participants of level I said thatof gaskets and exchanging gaskets.

contents of collective education were clear, and 80%

To validate the effect of education, we inspect“numberreplied that the certification method of practical skillsof re - rising pressure system caused by flange fastening”

was good. We had comments such as,“It was goodand compare it with the results of re-rising pressure atbecause changes of axial tension of each bolt at the time

the last regular repair in 2016. As shown in Table4, weof flange fastening were easy to comprehend which

halved the number of re-rising pressure system

made it possible to operate in a short amount of time.”

compared to the last results and lowered the risk ofWinter 2021

3-2）Findings from hearing of the participants

increase of the number of operations and extension of3-3）Findings from analysis of operators’ skills

the procedure, and a certain level of educational effectWe have analyzed operators’ skills, using the bolting

was recognized.

simulator. This simulator maintains a log of fastening

Table4 S urvey on number of re-rising pressure systemcaused by flange fastening

process which makes it possible to confirm characteristics
of operators with fastening（too much fastening, lack offastening or uneven fastening）. For this, we can giveComprehensive
airtightness test
number of strains

appropriate advice on that which leads to improve skills

307

with efficiency.

Number of re-boosting systems
2020 regularmaintenance2020 regular
maintenance
Number of points

2016 regular
maintenance（Reference value）

114520（Same scale as last time）

6

The result of analysis of operators’ skills this time shows

Next, regarding leaked flanges（14 flanges within 6that the ratio of too much fastening is higher, aboutsystems）which were the main cause of re-rising

twice, than that of lack of fastening. Furthermore, whatpressure, we show in Table5 the findings from our

we found from analyzing too much fastening, there wassurvey on the specifications of flanges and gaskets,a higher proportion of operators that fastened some ofreasons of leakage and layout of the scene. We found out

the bolts too much rather than generally fastening of

the main reasons of leakage as the following two：bolts too much. We think this is because of difference・Cleaning of surfaces of gaskets failed as the plumbingof axial tensions rising among bolts with operators’layout did not allow secure clearance between

postures. Regarding uneven fastening（there is a great

flanges when they were open.

variety among surfaces of flanges）, we think the set upat the initial stage is important and it is necessary to・F astening layout was not good as there wereobstacles, which led to uneven fastening.
6No.40Our engagement with improvement of quality in workmanship within a common certification system for flange fastening

Table5System
No.

1

Detailed investigation of the flange responsible for re-pressurization

Size（B）

Class（pound）

Workingpressure（MPa）

11/2

300

18ー

11/2

300

18ー

Cause of flange leakage

Flangeorientation

Tightening
layoutClearance between
flanges

3.35

One-sided tightening

VerticalDefective

Have clearance

3.35

Improper cleaning of the gasket surface

BesideDefective

Have clearance

3.35

One-sided tightening

VerticalDefective

Have clearance

3.35

Improper cleaning of the gasket surface

BesideDefective

Have clearance

6600

3.35

RJT poor rubbing

BesideGoodNo clearance

218ー

2.3

Deterioration due to aging of the gasket surface

VerticalGood

Have clearance

6300

1.48

Improper cleaning of the gasket surface

BesideGoodNo clearance

36300

1.48

Improper cleaning of the gasket surface

BesideGoodNo clearance

8300

1.48

Improper cleaning of the gasket surface

BesideGoodNo clearance

6150

0.42Improper cleaning of the gasket surface

VerticalGoodNo clearance

12150

0.42

Improper cleaning of the gasket surface

VerticalDefective

No clearance

411/2150

0.42

One-sided tightening

VerticalDefective

No clearance

5181501.08

Improper cleaning of the gasket surface

VerticalDefective

No clearance

61300

0.35

One-sided tightening

BesideDefective

Have clearance

As measures for these, we will continue engagement

Winter 2021
No.40

learned）are applicable at operation scenes.”

towards eliminating re-rising pressure tests by・We decreased the number of re-rising pressure systemsreviewing the operation manuals and education contents

at the comprehensive airtightness test, compared toso that we can carry out the right operation.

the previous（2016）regular repair.

4. Summary and overview for the future4-2）Overview for the future
ENEOS Holdings is planning to systematize education

4-1）Summary

by introducing the certification for flange fastening as・Certification system for flange fastening allows us towell as bolting simulator in all its refineries from now on.

standardize education and we do not need overlapped

Although it is possible to establish a certification systemeducation for users and operators.

that is shared within the country and not just for a・We can evaluate skills quantitatively by using thesingle company alone and can operate effectively for thebolting simulator, and with logs of fastening process,convenience of operators, there are many agendas

we can give right instructions to operators.

including unified maintenance of skill data of operators

・We had good feedback from the participants through aand controllers.

hearing regarding system operation（level III, level I）.

We will continue collaborating on this to completelyThey say“contents of lecture were clear,”“awarenesseliminate troubles caused by flange fastening in thewith flange fastening was raised,”and“（what wefuture in Japan.

Yosuke Koga
Regular Repair PlanningGroup
Kawasaki Refinery,
ENEOS Holdings
7

Shigeo Sakai
H&S Sales Division,Valqua, Ltd.