Materials Performance Supplements

Corrosion Management for Pipeline Integrity 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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3 CORROSION MANAGEMENT FOR PIPELINE INTEGRIT Y SUPPLEMENT TO MP MATERIALS PERFORMANCE JUNE 2018 Pipeline Protection Articles U.S. Study Targets More Data Usage on Pipeline Materials, Corrosion Ben DuBose, Materials Performance A new study 1 from the U.S. Government Accountability Office (GAO) (Washington, DC, USA) found a need for the Pipeline and Hazardous Materials Safety Administration ( P H M S A ) ( Wa s h i n g t o n , D C , U S A ) t o improve the agency 's use of materials and corrosion data for its primary risk assess- ment model. The GAO's performance audit was con- ducted from July 2016 to August 2017, with information collected through a review of existing PHMSA data, reports, and regula- tions; interviews with numerous PHMSA officials; and interviews with pipeline oper- ators and industr y stakeholders such as unions, training providers, and associa- tions to better understand the risk factors involved. PHMS A, an agency within th e U.S. D epar tm ent of Transpor tation (D OT), inspects gas and hazardous liquid pipeline operators and oversees federal safety regula- tions—including requirements for pipeline materials and corrosion prevention technol- ogies, as well as the establishment of design standards for pipelines specific to their operating conditions and pressures. While each operator takes primary responsibility for pipeline integrity, PHMSA conducts peri- odic inspections to ensure compliance. PH M S A e m p l o y s o v e r 2 0 0 st a f fe r s across its headquarters and five regional of f i c e s, w ith ab out 130 of th o se st af f involved in inspections and enforcement of interstate pipelines. To narrow its annual inspection list to a suitable number for its resources, PHMSA uses a Risk Ranking Index Model (RRIM) developed in 2012. However, according to the GAO, the RRIM used to prioritize these inspections has not been subject to data-based evaluation since its implementation. "Finding better ways to reduce the num- ber of corrosion-related incidents is a prior- ity for PHMSA," says Br yan Slater, who works with the DOT as the Assistant Secre- tary for Administration. Slater's comments were made in a letter to the GAO after receiving a draft report of the audit. While PHMSA's scope includes pipe- lines comprised of steel, plastics, and com- posites, most of the larger energy pipelines within its purview are comprised of steel, the GAO explains. This is because plastics and composites generally lack strength for use at higher operating pressures and diam- eters. Though steel is a stronger material, it is also more susceptible to corrosion. According to the GAO's analysis, 22% of the operator-reported causes of significant U.S. pipeline incidents between 2010 and 2015 were due to corrosion. External corro- sion often results when the pipe's metal sur- face is exposed to groundwater or soil envi- ronm ent s th at in crea se th e pip elin e's electrical conductivity. External corrosion is also a factor in stress corrosion cracking, where stress on the pipeline from high or fluctuating operating pressures and corro- sive environmental conditions can lead to cracks forming in the pipeline material, the GAO explains. Meanwhile, internal corro- sion inside the pipeline can be caused by the presence of water, corrosive materials, or bacteria. As a result, steel pipes require corrosion prevention technologies such as the com- bi n e d u s e of pro t e c tiv e c o ati n g s a n d cathodic protection (CP). Coatings are typ- ically applied prior to or during installation, and coat both the pipe and the welds that join pipeline segments together. Types of coatings typically used, according to the GAO study, include fusion-bonded epoxy coatings; three-layer polyethylene coatings; Corrosion was the largest operator-reported cause of significant pipeline incidents between 2010 and 2015. Image courtesy of GAO.

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