Post on 20-Jan-2016
description
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 () /
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 , , ,
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 .