2009 Chmilar

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Cathodic Protection Today:Part A: Standard Practice (NACE SP0169)Part B: Real Life on Pipelines and Facilities

IPEIA – February 2009Banff Centre

J.F. (Jim) Chmilar, P.Eng.Chmilar & Associates Consulting Ltd

Cochrane, Alberta

NACE Task Group 360

•• Review Standard Practice (SP) 0169 Review Standard Practice (SP) 0169 –– 2007 2007 (formerly RP0169), (formerly RP0169), ““Control of External Control of External Corrosion on Underground or Submerged Corrosion on Underground or Submerged Metallic Piping SystemsMetallic Piping Systems””

Chair: Jim Chmilar,

Vice Chair: Travis Sera, Southern California Gas Company Los Angeles,

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2002 ad hoc report to STG 05

• Section 6 could not be reaffirmed as it exists,• Ambiguity exists between the –0.850

copper/copper sulfate electrode (CSE) current applied criterion and –0.850 vs CSE polarized criterion,

• There is confusion regarding 100 mV formation and decay,

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2002 ad hoc report to STG 05

• More guidance is needed on cathodic protection (CP) criteria for controlling microbiologically influenced corrosion and corrosion at elevated temperatures,

• Upper limits on CP criteria for coating damage and /or high strength steels are needed.

STG 05 formed Task Group 285 to revise Section 6 in 2002

• At CTW 2006 RP0169-2002 reaffirmed; review of the entire document including Section 6 was turned over to Task Group 360 under STG 35.

• Part of the NACE and ANSI protocol requires all standards be revised or reaffirmed every 5 years.

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NACE Task Group 360 Work

• Developed a series of Eight Questions & Answers published in MP in December 2007 and February 2008

• Significant modifications and additions to Sections 5 and 6 and addition of an Appendix that covers a review of International Standards.

NACE Task Group 360 Work• 6.2 Criteria• 6.2.1 It is not intended that people responsible for external corrosion control be limited to any specific criteria. This

section contains criteria; however, it is acknowledged that other approaches have been successful in the past. The use of any approach to achieve corrosion control through CP is the responsibility of the user. It is important that the user be able to provide empirical evidence for any approach that is taken.

• 6.2.2. The two fundamental polarization criteria in this section have been shown to typically reduce the average corrosion rate of steel to less than 25 microns/yr (1 mil/yr) in soils and natural waters in the field and laboratory tests at ambient temperatures.3,4,5 A single criterion for evaluating the effectiveness of CP may not be satisfactory for all locations along a structure.

• 6.2.3 Steel and Cast Ductile Iron Piping• 6.2.3.1 External corrosion control can be achieved at various levels of cathodic polarization depending on the

environmental conditions. Any criterion selected must provide a reliable indication that the corrosion control objectives of the operator have been satisfied. In the absence of specific data listed in Paragraph 6.1.2 that demonstrate that adequate CP has been achieved, at least one of the following shall apply:

• 6.2.3.1.1 A negative (cathodic) voltage of at least 850 mV as measured with respect to a saturated copper/copper sulfate reference electrode. This potential may be either a direct measurement of the polarized potential, or a current applied potential corrected for voltage (IR) drops other than those across the structure/electrolyte boundary.

• 6.2.3.1.2 A minimum of 100 mV of cathodic polarization. The formation or decay of polarization can be measured to satisfy this criterion.

• 6.2.3.1.3 Criteria that have been shown to successfully control corrosion on piping systems can continue to be used on those piping systems.

• 6.2.3.1.4 Other criteria that can be demonstrated to achieve the corrosion control objectives of the operator.

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WE ARE NOT ELIMINATING THE 850 ‘ON’ CRITERIA


• 6.2.3.1 External corrosion control can be achieved at various levels of cathodic polarization depending on the environmental conditions. Any criterion selected must provide a reliable indication that the corrosion control objectives of the operator have been satisfied…

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• 6.2.3.1.1 A negative (cathodic) voltage of at least 850 mV CSE.This potential may be either a direct measurement of the polarized potential, or a current applied potential corrected for voltage (IR) drops other than those across the structure/ electrolyte boundary.


• 6.2.3.1.2 A minimum of 100 mV of cathodic polarization. The formation or decay of polarization can be measured to satisfy this criterion.

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6.2.3.1.3 Criteria that have been shown to successfully control corrosion on piping systems can continue to be used on those piping systems.


• 6.2.3.1.4 Other criteria that can be demonstrated to achieve the corrosion control objectives of the operator.

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“The -850 “on” success is largely due to two things:

1) For many pipelines, 100 mV of polarization is achieved at less than -850mV “off”meaning that -850 mV “on” has IR drop built into it (especially older poorly coated lines), and

“The -850 “on” success is largely due to two things:

2) While maintaining -850 mV ”on”, many “on”potentials on the same structure were considerably more negative than -850mV “on”

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TG 360 members agree that:• Operating companies need the ability to

utilize “on” potentials which are properly supported.

• In addition, we need to ensure that the language in the SP0169 document does not create an issue with regulators by wording of statements in a negative fashion.

NACE RP0169:• Approved April 1969• Revised Jan. 1972• Revised Sept. 1976• Revised Jan. 1983• Revised April 1992• Reaffirmed 1996-09-13• Reaffirmed 2002-04-11• Reaffirmed 2007-03-15 and

had name change to SP

Revision History SP0169

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• Path Forward: SP0169-2007, will be sent to the STG 35, STG 05 and STG 30 membership who have registered to be in the voting pool.

• Task Group 360 Secretary:

[email protected]

Part B: Real Life on Pipelines and Facilities

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• IF your system is not changing, you DO NOT NEED to do interrupted surveys every year. Maybe once every 4 to 5 years and then if practical.

• Use Coupon technology as another tool

?Questions

THANK YOU

2009 Chmilar

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