Advisory Bulletin on Pipeline Safety: Deactivation of Threats
Background: PHMSA issued an Advisory Bulletin to inform owners and operators of gas transmission pipelines that PHMSA has developed guidance on threat identification and the minimum criteria for deactivation of threats. The Advisory Bulletin also provides guidance to gas transmission pipeline operators regarding documenting their rationale of analyses, justifications, determinations, and decisions related to threat deactivation. PHMSA notes that a critical element in an integrity management (IM) program is the identification of threats to pipeline integrity. According to the Standard established by the American Society of Mechanical Engineers (ASME), an operator must consider nine individual threat categories as part of an IM program.
These threats include: (1) External Corrosion; (2) Internal Corrosion; (3) Stress Corrosion Cracking; (4) Manufacturing; (5) Construction; (6) Equipment; (7) Third-Party Damage; (8) Incorrect Operations; and (9) Weather-Related and Outside Forces. According to PHMSA, an IM program should provide criteria for eliminating a threat from consideration during a risk assessment; however, PHMSA regulations (49 CFR Part 192—Subpart O) do not include provisions for the permanent elimination of threats. An operator, therefore, must continually consider all threats in the evaluation of their IM program through periodic reviews and assessments. PHMSA also acknowledges that threats may be categorized as active, requiring an integrity assessment, or inactive, meaning that during a specific assessment cycle the threat does not trigger an integrity assessment. Operators, however, must understand that threats to a pipeline are not static, but vary over time. An operator must continually monitor operations and maintenance (O&M) and other activities, integrating relevant information during a threat analysis that might indicate a change in the status of a threat. With regard to the threat from “Construction,” PHMSA notes that there is substantial guidance provided in the original Gas Transmission IM protocols, PHMSA regulations, and the PHMSA Gas Transmission IM FAQs regarding deactivation of construction threats. Specifically, PHMSA regulations at 49 CFR 192.917(e)(3) provide guidance for determining when a construction threat is active, stating, “[i]f any of the following changes occur in the covered segment, an operator must prioritize the covered segment as a high-risk segment for the baseline assessment or a subsequent reassessment: i. Operating pressure increases above the maximum [allowable] operating pressure [MAOP] experienced during the preceding five years; ii. MAOP increases; or iii. The stresses leading to cyclic fatigue increase.”
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