Pipeline Safety: Corrosion Threat to Newly Constructed Gas Transmission and Hazardous Liquid Pipelines

AGENCY:

Research and Special Programs Administration (RSPA), DOT.

ACTION:

Notice; issuance of advisory bulletin.

SUMMARY:

RSPA's Office of Pipeline Safety (OPS) is issuing this advisory bulletin to owners and operators of natural gas and hazardous liquid pipelines to consider the threat from external corrosion during and immediately after construction of new steel pipelines or pipeline segments. Operators are strongly encouraged to determine whether new pipelines are susceptible to interference and damage from stray electrical currents. Operators should carefully monitor and take action to mitigate any detrimental effects.

FOR FURTHER INFORMATION CONTACT:

Richard Huriaux, (202) 366-4565; or by e-mail, richard.huriaux@rspa.dot.gov. This document can be viewed at the OPS Home page at http://ops.dot.gov. General information about the RSPA/OPS programs may be obtained by accessing RSPA's Home page at http://rspa.dot.gov.

I. Advisory Bulletin (ADB-03-06)

To: Owners and Operators of Gas Transmission and Hazardous Liquid Pipeline Systems.

Subject: Corrosion Threat to Newly Constructed Gas Transmission and Hazardous Liquid Pipelines.

Purpose: To advise owners and operators of natural gas transmission and hazardous liquid pipelines to consider external corrosion as a possible safety risk to newly constructed pipelines and to identify and remediate the detrimental effects of stray currents during and after construction.

Advisory: Each operator of a natural gas transmission or hazardous liquid pipeline should determine whether new steel pipelines are susceptible to detrimental effects from stray electrical currents. Based on this evaluation, an operator should carefully monitor and take action to mitigate detrimental effects. The operator should give special attention to a new pipeline's physical location, particularly a location that may subject the new pipeline to stray currents from other underground facilities, including other pipelines, and induced currents from electrical transmission lines, whether aboveground or underground. Operators are strongly encouraged to review their corrosion control programs and to have qualified corrosion personnel present during construction to identify, mitigate, and monitor any detrimental stray currents that might damage new pipelines.

SUPPLEMENTARY INFORMATION:

II. Background

This action follows the discovery of substantial external corrosion on a newly constructed gas transmission pipeline. The pipeline had been in service a little over two years when this unexpected corrosion was revealed by a high-resolution, inline inspection tool. The pipe wall pitting was consistent with that caused by underground stray electrical current before a cathodic protection system is installed. In some isolated areas, the pipeline exhibited more than 50% wall loss. Corrosion due to stray current is most often found on pipelines that cross other underground structures (such as other pipelines) or that follow overhead electric transmission lines.

Pipelines are often routed along common use right-of-ways. This presents complicated corrosion scenarios that must be addressed by corrosion engineers. In some instances, the common right-of-way includes high voltage power lines that can induce alternating current on a new pipeline. This can result in significant corrosion damage to the pipeline in a short period. In other instances, the common right-of-way will cross or parallel foreign pipelines. This requires consideration of the effects of electrical interference from foreign pipeline cathodic protection systems, both on the new pipeline and on the existing foreign pipeline.

Corrosion control on gas transmission and hazardous liquid pipelines is addressed in the Federal Pipeline Safety Regulations at 49 CFR part 192, subpart I and part 195, subpart H. Although 49 CFR 192.455(a)(2) and 195.563(a) state that a cathodic protection system must be installed and placed in operation within one year after completion of construction, operators are encouraged to have qualified corrosion personnel identify, mitigate, and monitor any detrimental stray currents prior to and during construction.

Operators should refer to recommended practices provided by national consensus standards organizations, such as the American Society of Mechanical Engineers (ASME) standards B31.4 and B31.8, NACE International (NACE) corrosion standards, and Gas Piping Technology Committee (GPTC) guidance documents for help in addressing stray underground electrical current interference on gas transmission and hazardous liquid pipelines.