가스배관가스배관 시공시공 및및 유지관리유지관리 기술기술

현황현황

가스산업 워크숍 발표

김우식

한국가스공사

Why pipeline? (1)

Pipeline에 의한 에너지 수송이 가장 경제적이다

$1 will move one ton of petrochemical:

- Truck 19 miles

- Rail 45 miles- Rail 45 miles

- Ship 200 miles

- Pipeline 238 miles

In case of NG: LNG(ship) vs PNG(pipeline)

the split point is 3,000 km

� Pipelines are 40 times safer than railroad tank cars, and 100times safer than highway tank trucks.

� Between 1986 and 1995, the 500,000 mile oil and gas

Why pipeline? (2)

Pipeline에 의한 에너지 수송이 가장 안전하다

� Between 1986 and 1995, the 500,000 mile oil and gas transmission pipeline system in the USA, accounted for 63 deaths and 396 serious injuries.

� In 1995 alone:� 41,480 people died on that nation’s highways� 831 died in rail accidents� 621 died in recreational boat accidents� 621 died in non-commercial aviation accidents

Pipeline Construction

� Cost

� $1M-$1.5M per mile for cross country pipelines

� $3M-5M per mile for offshore pipelines

Materials (Linepipe)

Welding & Inspection

� Technology Options include:

� High Strength Pipe

Other

� Reduced Material Costs

� Higher Operating Pressures

� Higher Design

� Higher Operating Pressures

� High Productivity Welding / Inspection

� High Speed Root Pass Welding

� High Production Fill Pass Welding

� Automated Ultrasonic Testing/ PA-AUT

� Improved Construction Methods & Equipment

고강도 대구경 배관의 필요성

� 에너지 수송의 경쟁력은 수송효율에 의해 결정됨

� 수송효율의 최대화는 수송압력 증대 및 대구경화에 의해달성됨

� 대구경화와 수송압력 증대는 배관 소재 등급의 향상을 통� 대구경화와 수송압력 증대는 배관 소재 등급의 향상을 통하여 가능하게 됨

D

tSEFTP

2=

t : 배관의 최소두께 (mm)P : 설계압력 (kg/㎠)

Do : 배관의 외경 (mm)

S : 재료의 항복강도 (kg/㎠)

E : 길이 이음의 용접효율

T : 온도계수

F : 설계계수 (3단계 구분)

연도별 배관등급 변화 추세

재료등급 분율(%)

X52 3.46

X60 9.46

• 1990년대 건설배관등급 통계

X60 9.46

X65 41.67

X70 42.73

X80 2.68

• 같은 조건에서 X65 → X80 변경시 7.5% 비용 절감

배관재료, 용접시공분야 기술 비교

기술분야 국내 수준 국외(일본, 유럽) 수준

API 소재• 후판 X70 연구

• 박판 X70 생산

• 후판 X80 생산

• 박판 X80 생산

강관 제조

• 후판 대구경 X70 roll bending

• 박판 대구경 X70 spiral

• 후판 X80 roll-bending, UOE

• 박판 X80 spiral• 박판 대구경 X70 spiral • 박판 X80 spiral

용접시공 • 수동상진 원주용접• 수동하진

• 자동, 반자동 용접

비파괴검사기기• 원주용접부 100% RT 적용

• 지오 피그 시제품

• RT, UT 적용

• MFL 피그 상용화

평가 및 기준 • 국내 배관(X65)평가 기준 보유 • 배관 특성에 맞는 평가 시행

용접 시공 기술 비교용접 시공 기술 비교

항목 한국 미국 /

캐나다일본 중국

용접기법

SMAW

수동용접

GMAW

수동 및 자동용접

GMAW

자동용접

FCAW

반자동 용접

초층용접

GTAW

(수동)

GMAW

(자동)

GMAW

(자동)

SMAW

(수동, 하진)

비고생산성

(2joints/day)

Alliance pipeline (평균

100joints/day) ?서기동수

용접 시공 기술 비교용접 시공 기술 비교

FCAW 반자동 용접

SMAW Pipeline Welding

Long Distance

Pipeline

방사선 투과시험 검사결과 처리흐름도

Film필름카세트

운반

Film Based Radiography

Indirect Computed Radiography

현상,정착,건조

관찰

Film Digitisation

FilmScanner

Film필름카세트

운반

Film Based Radiography

Indirect Computed Radiography

현상,정착,건조

관찰

Film Digitisation

FilmScanner

Imaging

Plate

반도체

검출기

Indirect Computed Radiography

Direct Computed Radiography

Imaging Plate운반

CR ScannerImaging

Plate

반도체

검출기

Indirect Computed Radiography

Direct Computed Radiography

Imaging Plate운반

CR Scanner

원주용접부 자동UT 시스템

AWS-4 (Force Institute) MIPA(KrautKramer)AWS-4 (Force Institute) MIPA(KrautKramer)

Rotoscan(RTD) AS-200s(Scanmaster)

원주용접부 UT 신기술

� 다중집속 초음파탐상기술 � 위상배열 초음파

• ASTM-1961-98: Standard Practice for Mechanized

Ultrasonic Examination of Girth Welds using Zonal

Discrimination with Focused Search Units

* 중국의 “서기동수”사업에 적용

가스배관건전성확보체계 흐름도배관감시

위험성평가 결함보수

•피복탐측•방식전위, 부식환경조사•타공사감시•교육훈련

•사용적합성평가•잔여수명예측•피로

•인텔리전트피그검사•수압시험

배관검사 결함평가

•보수절차서•배관자료D/B•우선순위관리•배관검사방법및주기결정

How Do Pipeline Manage Risk

� Reduce the probability a failure will occur

� Reduce the consequences of a failure

� Focus resources on the highest risk areas

� Pipelines can be damaged.

� Assessment Philosophy

Pre-Service

� Hydrostatic Test To Yield

� Repair All Failures

In-Service

� On-Line Inspection + Other Monitoring Activities

� Repair Significant Damage

� Assessment Philosophy

� TO SAFELY INSPECT, ASSESS & REPAIR DAMAGED PIPELINES

� Consequences of the incident

Identify the Risk Components

� Probability of an incident occurring

� Outside Force

� Corrosion

� Material failure

� Fatality

� Injury

� Property damage� Material failure

� Construction defect

� Equipment failure

� Human error

� Property damage

� Production loss

� Environmental

Degradation

Conclusions from the fifth EGIG* report

� In the period 1970 to 2001 no incident on a natural gas transmission pipeline caused fatalities or injuries to inhabitants.

� The participating companies now have an accumulative exposure of their pipeline system of 2.41 million kilometers-years.

� The overall incident frequency with an unintentional gas release over the period 1970 to 2001 is 0.44 incidents per year per 1000km. However, the figure over the past 5 year is significantly lower; 0.21 incidents per year per 1000km pipeline.incidents per year per 1000km pipeline.

� There is a trend to use large diameter pipelines (>42inch) in combination with a higher grade of material (X65 and X70)

� The major cause of incidents is still external interference (50%), followed by construction defects/material failures (17%) and corrosion(15%)

� A larger proportion of the incidents is detected by the public, the second highest detector is patrol survey.

* European Gas Pipeline Incident Data Group (EGIG) : 유럽 8개국

Steps in an FFS Assessment

� Flaw and damage mechanism identification

� Applicability and limitations of the FFS assessment

procedures

� Data requirements (material, operation, stress, NDT)

� Assessment techniques and acceptance criteria� Assessment techniques and acceptance criteria

� Remaining life evaluation

� Remediation

� In-service monitoring

� Documentation

Example: Corroded pipeline assessment method

0.5

0.6

0.7

0.8

0.9

1.0API 5L X65, 30inch, 17.5mmt

SMYS=448MPa(210kgf/cm2)

UnacceptableDefects

COPAP ASME B31G Modified B31G Chell Kanninen Sims wide Ritchie PCORRC BG/DnV Level 1

Defect Depth Ratio(d/t)

0 100 200 300 400 500 6000.0

0.1

0.2

0.3

0.4

0.5

AcceptableDefects

Defect Depth Ratio(d/t)

Corrosion Length(mm)

Integrated Maintenance

Internal

inspection

Assess

Predicted No. of

Corrosion

FeaturesRepair

Failure

Inspect when ‘x’ features

require repair

Deterministic approach

Assess

pipeline

condition

Estimate

corrosion rates

Optimum

timing of next

inspection

Prediction of

future

condition

Failure

Or inspect before one

feature can fail?

Time, yearsRe-inspect

Advanced Integrated Maintenance

Probabilistic approach

Repeat internal

inspectionsProbability of

failure Probability of one

or more failures

Corrosion

rate

Actual corrosion

rate distributions

Assess

probability of

failure

Optimum

timing of next

inspection

Predict

probability of

failure vs time

Target Probability

Time, yearsRe-inspect now

Repair Methods

� Dressing using grinding tool

� Epoxy shell

� Clock-spring

� Weld depositionSevere

� Sleeve weld

� Hot tap

� Leak clamp

� Cut out

Severe

defect

Weld Deposition, Clock-spring

Weld Deposition

Clock-spring

Sleeve Repair

Sleeve Welding Epoxy Sleeve

요 약

� 배관시공: 재료, 용접, 비파괴검사

� 가스배관 유지관리: 사용적합성평가와 보수 기술

� 가스업계 공동투자에 의한 연구로 관련기술 개발 필요.� 가스업계 공동투자에 의한 연구로 관련기술 개발 필요.