ECDA 2005. 3. 29.

KOGAS

ILI

ILI

PIAM feed-back

1995-2002 DCVG

DCVG DCVG . .

DCVG IP , .

ILI DCVG

(m)Metal loss (mm)DCVGCIPSDepth(%)1-412.6421329( )- 26029.31186859 3-8115.7--- 49751.9999859 5-13049.82213222--- 615010.38851858 -- 715129.014018042 --817341.751623 ()-9-23991.016814127 10-42384.936932534 11-24007.023444436

and/or/ /

Piggable line: ILI Unpiggable line: DCVG

ILI ECDA(External Corrosion Direct Assessment) KOGAS-ECDA 2005

KOGAS () /

()- 2- CIS ?OFF -850-950 PIAM %IR > 16% ?

DCVG

CIPS ( 15-20 m 2~3 m ) ILI/ECDA

OFF : -850mV / : -950 mVcf. SRB : -950mV () : -1700mV (On, TGC)

2 ON/OFF 1 ON 1

CIS : ECDA

( )

ECDA , , -, - (2005. 3. )

DCVG/CIPS

KOGAS Pipeline

(km) (km) 10 kg/cm220 kg/cm250 kg/cm270 kg/cm2 561231842,0722,435ILI -941841,6561,934ILI 56(100%)29(23.5%)0(0%)416(20.0%)501(20.5%)ILI -(0%)79(64.2%)165(89.7%)906(43.7%)1,150(47.2%)(98km)

Unpiggable Lines in KOGAS

(Inch) (km) -20121987-20231988-20132000-20101992 -20191993-20121993-20201995-30531998-30691999 -30341999-30192000-30191997-30982002-30792002

ILI (GRI-02/0087) 33% ILI (2002)

75% ILI 40 ( )

25% unpiggableILI ECDA . (25% + (42%))

Pressure Test

In Line Inspection (ILI-MFL)

Direct Assessment (DA)

Others

ILI-MFL ()T. Morrison et al, IPC 2000ILI-MFL ILI .

ILI-MFL 10% , 80% 5 10% 50% reasonable, 50%

. (threshold value) .

ECDA (External Corrosion Direct Assessment) (CP) , , / /

knowhow: : (external corrosion) (pre-assessment), (indirect inspection), (direct examination), (post assessment) 4

ECDA ///Guideline49CFR192.923 - 931 ( )

ASME B31.8S Section 6.4ASME B31.8S Appendix B2 & A3

NACE RP0502 (Methodology)Shall/MustShould Statements

GTI 04/0071 (Implementation Protocol)

ECDA () NACE RP0502 , , ,

1: (PRE-ASSESSMENT)ECDA TOOL SELECTION MATRIX*1: - (

ECDA REGION - EXAMPLE ,

(INDIRECT INSPECTION)ECDA Implementation Protocol, GTI 04/0071, Gas Technology Institute (2004)

CIS (25 ft to 5 ft)5 ft interval25 ft interval

ECDA - DCVG

% IR

5 ft interval25 ft interval

DCVG - %iR5 ft interval25 ft interval

DCVG - %iR5 ft interval25 ft interval

CP On/Off CIS (ECDA Step 2) (ECDA Step 3) corrosion active/passive .. . . . pH .

CASE 1: Active corrosionCASE 2: Passive corrosionOFF

(, off) ( , cm) 40cm ( ) .

active/passive corrosion

(RP0502, GTI-04/0071)

- (CIS)

DIRECT EXAMINATION (urgency of excavation) (Immediate action required) (Schedule for action required)(Suitable for monitoring)

/ feedback

Taken from NACE RP0502 Table 4

()

1: CIS + CI(P)SSevereModerateMinorNI(cm)< 3,000I*S*S*M*3,000 7,000I*S*M*M*7,000 20,000I*S*M*NI*> 20,000S*M*M*NI*

KOGAS / pH

()

FOR:SM (safety margin) = 0.6GR () = 10 mil/yT () = 0.330 1/2 ECDA !!!

Maximum pit depth/burial time 0.4 mm/y*10.3 mm/y at least 40mV CP

LPR measurement (ASTM G59) + pitting indexCorrosion coupon*1. Upper 80% confidence level of maximum pitting rates for long term (up to 17y) underground corrosion tests of bare pipe coupons without CP in a variety of soils including native and non-native backfill.

ECDA ()Selection CriteriaIdentified by Risk Management ProgramPrimary Threat External CorrosionNot piggable8 OD changes10 plug valves

ECDA ()20 mile section in study area24-34 inch, 400# MAOP, 20 to 40% SMYS, 1944 HAA, 1974 Tape13 Integrity Management Areas (IMAs)6300 under streets, 6000 under concrete, 4950 under soil, 2300 in paved parking, 2150 in backyards

EXAMPLE Result of ClassificationGood alignment between techniquesCP was protecting poorly coated section of pipeResults appear rational

EXAMPLE Poor Condition

EXAMPLE Excavation dataData ElementDig 1Dig 2ECDA Region132-1132-2Coating TypeWrapHAAPipe-to-Soil (mV)-1051-971Soil Resistivity 684684Coating Condition Partially Disbonded Partially DisbondedLiquid underneath coatingYesYesSoil pH5.56.0Pipe pH7.48.0CorrosionNoYesPit Depth (inches)0.015 to 0.031

EXAMPLE Corrosion Morphology

ILI/ECDA () GTI 04/0071

ECDA DCVG ? .DCVG , ECDA .

.DCVG ECDA .

ECDA , , feedback

- ECDA , , , 2 feedback

KOGAS ECDA DCVG: :

ECDA (-, -) NACE RP0502 , .

. . ILI , , . ILI / , / . . ., . . ILI . 2 ., ILI ILI . , ILI . PIAM( ) . , , . , , . . ILI / . , 90 . . ILI piggability . .

ILI ECDA( ) . KOGAS ECDA . 05 .

. .

. .DCVG , ILI .CIPS 15~20m . -850 mV , - 950mV . EDCA .ECDA , , , . NACE , . ECDA . CIS DCVG DCVG . . -850mV ., . ., . , . , pH , .

. , , . , . . .ECDA DCVG DCVG . ECDA . . DCVG , ECDA , . . DCVG ECDA .