PIPELINE
TECHNICAL REFERENCE
49
CFR Ch. 1
(10-1-04
Edition)
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PIPELINE
TECHNICAL REFERENCE |
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| THIS SECTION INCLUDES: | ||
| The advertisement below shows a cross section of quotations from papers and articles concerning cathodic shielding. Below is a list of these articles and some others we have collected concerning CP shielding. The articles are listed in approximate chronological order, with commentary and links in some cases. | ||
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| 1988 |
| An early summary of
this problem was the 1988 Pipeline Research Council, which identified
the CP shielding problem as a prime cause of both corrosion and SCC.
Additionally, this study was the first to indicate that shielding coatings
might help to defeat defect survey systems.
Along with similar Canadian research, this study was probably responsible for the beginning of the decline of use of solid film backed corrosion coatings in North America. |
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Excerpt
Page 3 "A Review of Gas Industry Pipeline Coating Practices" |
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Excerpt
Page 4 "A
Review of Gas Industry Pipeline Coating Practices" |
Pipeline Research
Committee, "A
Review of Gas Industry Pipeline Coating Practices", Pipeline
Research Council International, 1988, p.3 and 4, Published by Technical Toolboxes, Inc., 3801 Kirby Drive, Houston, TX 77098 |
| 1989 |
| An early consensus definition of cathodic shielding was given in this informally circulated document. |
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Excerpt
Page 1 "Cathodic Protection Shielding Definition" |
Nunez, S., Eastman, A.D. et al, 1989, "Cathodic
Protection Shielding Definition", AGA Corrosion Supervisory Committee |
| 1993 |
| This failure report does not qualify as research, but since we showed it in one of our advertisements, we should show its source. It is indicative of a growing awareness in the field of a growing concern with the CP shielding problem. |
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Excerpt "OPS
DOT Report ID 910001" |
"OPS
DOT Report ID 910001", 1993, p.498 |
| 1995 |
| This report, concerning ruptures and fires on a Manitoba natural gas line, includes a definition of how CP shielding by polyethylene backed coatings encourages SCC. |
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Excerpt page 10 "TSB Canada Report P95H0036,1995" |
Transportation Safety Board of Canada, Report Number
P95H0036, 1995 www.tsb.gc.ca/en/reports/pipe/1995/p95h0036/p95h0035.asp |
| 1996 |
| This extensive report concluded that polythylene tapes had coated 76% of SCC pipeline failures in Canada between 1977 and 1996 (table 6.1, pgs. 102-103). Another conclusion was (p.29) as highlighted above. |
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Excerpt page 29 "SCC Report" 1996 |
National
Energy Board, "Report of the Inquiry Stress
Corrosion Cracking on Canadian Oil and Gas Pipelines" 1996 |
| 1998 |
| This recommendation, resulting from a Texas failure which caused two fatalities, concluded with a recommendation that included; "Revise 49 Code of Federal Regulations Part 195 to include performance measures for the adequate cathodic protection of liquid pipelines. (P-98-36)." |
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NTSB
Safety Recommendations, November 18, 1998, Ref P-98-34 through 38 |
| 1999 |
| This report, concerning a 20,600 bbl.spill from a Saskatchewan crude oil line, includes a conclusion that CP shielding by polyethylene backed tape coatings (p.6); 'has also resulted in a much higher susceptibility to producing general surface corrosion and NAEC-type defect conditions.' |
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Transportation Safety Board of Canada, Report Number
P99H0021,1999 www.tsb.gc.ca/en/reports/pipe/1999/p99h0021/p99h0021.asp |
| 2000 |
| This paper discusses the shielding problem, and summarizes the research to date concerning the proof that FBE does not shield cathodic protection currents. |
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Neal, D., Spring 2000, "Pipeline Coating Failure-Not
Always What You Think It Is", NACE Corrosion 2000, Paper 00755, p.5 |
| 2001 |
| This investigative report on a crude oil pipeline rupture in Alberta points to cathodic shielding as a sause of both corrosion and significant SCC. This line had at least three previous reported failures in which cathodic shielding under disbonded solid film back corrosion coatings was held to be a cause. |
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Transportation
Safety Board of Canada, Report Number P01H004, 2001 |
| 2002 |
| In 2002, NACE issued RP0169-2002, which includes instructions not to use shielding materials on the pipeline. |
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NACE Standard RP0169-2002, "Control of External Corrosion
on Underground or Submerged Metallic Piping Systems" NACEInternational,
Houston, TX 77084-4906, p.4 |
| 2002 also saw the issuance of new federal regulations which called for coatings which support cathodic protection. As of 2007, both CFR §192.461 (natural gas) and CFR §195.559 contain the requirement that coatings must support CP. |
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2003 |
| An unpublished investigation of field applied girth weld coatings, performed for a large pipeline operator by a major engineering company, noted that shrink sleeves may; "...shield the cathodic protection, rendering it ineffective if they disbond from the pipe surface". |
| 2004 |
This 2004 article discusses the non-shielding behavior of Polyguard's RD-6™ coating system. A link to the complete article is below. |
Norsworthy, R. June
2004 - "Coatings
used in conjunction with cathodic protection - "Fail/Safe" Pipeline
Coating Systems" p. 34-38 Materials Performance - June 2004 |
| 2005 |
| This 2005 NACE paper identifies all forms of solid film backed corrosion coatings with problems of long term CP shielding and associated corrosion risks. |
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Argent, C.A., and Norman, D., 2005, "Fitness
for Purpose Issues Relating to FBE and Three Layer PE Coatings", David Norman Corrosion
Control, Cornwall, TR8 5SA, England |
| This 2005 report identifies "ability to pass CP current" as one of three crucial properties for corrosion coatings in preventing SCC. |
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Michael Barker Jr. Inc., January 2005, "Stress Corrosion Cracking Study
- Final Report", USDOT OPS Delivery Order DTRS56-02-D-70036 |
| 2006 |
| The newly released volume 13C of the ASM Handbook identifies the ability of the coating to conduct CP current should the coating fail as one of "two primary factors" in preventing corrosion. |
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Beavers,
J.A. and Thompson, N.G., "External
Corrosion of Oil and Natural Gas Pipelines", |
| 2006 |
| Shrink sleeves were included in published research by CC Technologies on shielding behavior of pipeline coatings. However, they were included to represent the extreme of "complete shielding". FBE was used to represent a coating "transparent to CP". |
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Ruschau, G.R. and Chen, Y., 2006, "Determining the
CP Shielding Behavior of Pipeline Coatings in the Laboratory", NACE International, Houston, TX 77084, Paper No. 06043, p.4 http://www.nace.org/nacestore/assets/paperabstracts/2006/06043.pdf |
Concern about SCC and other corrosion problems created by CP shielding
is becomming more intense. |
PUBLISHED
PAPERS AND ARTICLES ABOUT POLYGUARD RD-6™ |
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1. "Coatings used in conjunction with cathodic protection — "Shielding vs. Non-Shielding" Pipeline Coatings" Presentation #4017 at NACE Convention 2009 . |
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2. "Coatings used in conjunction with cathodic protection - "Fail/Safe" Pipeline Coating Systems" - *Materials Performance - June 2004 |
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5. "Addressing Soil Stress and CP Shielding Used by a Woven Geotextile Fabric-Backed Tape System with Rubber Modified Bituminous Compound." **Presentation at NACE Corrosion 2000. |
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6. "Rating Underground Pipeline Tape and Shrink Sleeve Coating Systems" ***Materials Performance - Nov. 1999 |
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| * Reproduced with permission from NACE International, Houston, TX. All rights reserved. Published in the June 2004 issue of Materials Performance.© NACE International 2004. | |
| **Reproduced with permission from NACE International, Houston, TX. All rights resered. Paper #00769 presented at Corrosion 2000, Houston, TX. .© NACE International 2000. | |
| **Reproduced with permission from NACE International, Houston, TX. Published in the November 1999 issue of Materials Performance. .© NACE International 1999. | |
| 2008 | |
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CIS
Oil and Gas "Ask the expert: What can cause disbondment in three-
layer pipe coating systems?' 2008 www.cisoilgas.com/pastissue/printarticle?art=268860 |
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Studies comparing RD-6™ to other protective coatings. |
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