Recommended Revisions in 49 CFR 192, ASME B31.8, and ASME B31.8S
This report was prepared by Kiefner and Associates, Inc. (Kiefner) as part of the research project titled “Investigate Damage Mechanisms for Hydrogen and Hydrogen/Natural Gas Blends to Determine Inspection Intervals for In-Line Inspection Tools” for the U.S. Department of Transportation (USDOT), Pipeline and Hazardous Materials Safety Administration (PHMSA), under Contract 693JK32310011POTA.
The objective of the Task 3 work was to recommend changes to 49 CFR 192 Transportation of Natural and Other Gas by Pipeline: Minimum Federal Safety Standards, ASME B31.8 Gas Transmission and Distribution Piping Systems, and ASME B31.8S Managing Systems of Integrity of Gas Pipelines (Supplement to ASME B31.8). The recommended changes apply to the reassessment interval determination for defects in pipelines transporting hydrogen or hydrogen/natural gas blends as detected by in-line inspection (ILI).
Based on the analysis of Codes and Standards, review of publicly available literature, evaluation of the results of the analyses performed in Tasks 1 and 2 of this project, and the discussions included in this report, the following recommendations were formulated:
For 49 CFR 192 Subpart A – General
- Kiefner recommends that PHMSA remove the words “introductory text and ” from Section 192.7(c)(7), because the introductory text in Section 192.907 no longer exists. Without this change, the text in 192(c)(7) is confusing.
- Kiefner recommends that PHMSA update 49 CFR 192 to incorporate by reference API STD 1163, 3rd edition for ILI systems qualification.
- Kiefner recommends that, until such additional requirements are provided in ASME B31.8S, PHMSA incorporate by reference API RP 1176, the industry-recommended practice for managing pipeline cracking, into 49 CFR 192.
- Kiefner recommends that PHMSA incorporate by reference API RP 1176 into 49 CFR 192 to require operators of hydrogen and hydrogen/natural gas blended pipelines to develop crack management plans and procedures within their integrity management programs (IMPs), based on industry-recommended practices.
For 49 CFR 192 Subpart M – Maintenance
- Kiefner recommends that PHMSA issue an advisory bulletin to remind operators to update their risk assessments for hydrogen considerations and perform ILI with tool technologies appropriate to detect indications susceptible to the effects of hydrogen degradation for pipelines being considered for hydrogen blending or transportation.
- Kiefner recommends that PHMSA issue an advisory bulletin to remind operators to consider the interaction of hydrogen’s potentially detrimental microstructural effects on the material properties used in crack analysis models.
- Kiefner recommends that PHMSA explicitly include hydrogen effects to fatigue as a threat when determining reassessment intervals and require fatigue crack growth models to be considered within 49 CFR 192.
- Alternatively, at a minimum, Kiefner recommends that PHMSA issue an advisory bulletin to reinforce the expectation for operators to consider the effect of hydrogen on the fatigue life in crack growth models used to determine reassessment intervals for anomalies previously considered non-susceptible to environmental effects.
For 49 CFR 192 Subpart O – Gas Transmission Pipeline Integrity Management
- Kiefner recommends that PHMSA issue an advisory bulletin highlighting the outcomes of recent research on hydrogen transport to remind operators of the applicable risk changes associated with hydrogen transportation in pipelines that are not purpose-built for that product.
- Kiefner recommends that PHMSA issue an advisory bulletin based on this report’s findings to inform operators of their responsibility to consider the additional risks that hydrogen and hydrogen blends have on existing pipelines, including the effects of fatigue and crack growth rates, prior to converting a pipeline or transporting these products.
- Kiefner recommends that, given the additional risk imposed by hydrogen fatigue crack growth rates, the requirement should be updated to require operators to consider any change in pipeline operation or product that may change the basis of a prior analysis, perform a new cyclic fatigue analysis, and evaluate the effects of fatigue on existing anomalies within the pipeline.
- Kiefer recommends that PHMSA issue an advisory bulletin to remind operators to consider the embrittlement effects of hydrogen on crack-like anomalies and that tools capable of assessing a pipeline for cracks should be used on pipelines transporting hydrogen or hydrogen blends.
- Kiefner recommends that PHMSA update the incorporation by reference (IBR) in 192.933(d) to the 2022 edition of ASME B31.8S.
For ASME B31.8 Gas Transmission and Distribution Piping Systems
- Kiefner recommends supporting the balloting items being proposed and the review process being followed by the Hydrogen Task Group of ASME B31.8.
For ASME B31.8S Managing Systems of Integrity of Gas Pipelines (Supplement to ASME B31.8)
Review of Potential Threats to Integrity
- Kiefner recommends adding the following missing integrity threats applicable to any gas transmission pipeline to Paragraph 2.2 of future versions of ASME B31.8S:
- “Time-Dependent – Fatigue Cracking”
- “(b) Resident (1) Manufacturing-related defects (a) Defective pipe seam – Low toughness seam”
- “(b) Resident (1) Manufacturing-related defects (a) Defective pipe seam – Defect in or near an electric resistance welded (ERW) seam”
- “(b) Resident (2) Welding/fabrication-related – At in-service/repair welds – Hydrogen stress cracking”
- Kiefner recommends adding the following missing integrity threats applicable to gas transmission pipelines in hydrogen and hydrogen blend service to the future ASME B31.8S hydrogen chapter:
- “Time-Dependent – Hydrogen-induced cracking (HIC)”
- “Time-Dependent – Fittings and sharp transitions”
- “(b) Resident (2) Welding/fabrication-related – Near girth welds, and near in-service/repair welds – Arc burn/strike on pipe body”
- “(b) Resident (2) Welding/fabrication related – At welded sleeves and fittings – Type B sleeves and Puddle welds”
- “(b) Resident (2) Equipment – Other material/equipment failure – Disbonded coating caused by hydrogen”
- “(c) Random or Time Independent (3) Weather-related and outside force – At locations that may experience an electrical arc or fire – Fire damage”
Description of Hydrogen Effects
- Kiefner recommends using consistent terminology when describing hydrogen effects.
- Kiefner recommends that Table 5. Summary of Hydrogen Terminology of this Task 3 report be included in ASME B31.8S.
- Kiefner recommends adding the hydrogen terms that are not currently mentioned if they are going to be used within ASME B31.8 or ASME B31.8S (when Table 5 is added).
Review of ASME B31.8S-2018 Table 5.6.1-1 Integrity Assessment Intervals and ASME B31.8S‑2018 Figure 7.2.1-1 Response Time
- Kiefner recommends introducing the concepts of remaining life (RL) and reinspection interval (RI) into the Code while maintaining the concept of response time (RT).
- Kiefner recommends revising ASME B31.8S-2018 Table 5.6.1‑1 and Figure 7.2.1‑1 with consistent application of predicted failure pressure (Pf) and factors related to the specified minimum yield strength (SMYS).
- Kiefner recommends that ILI anomalies be assessed with a more realistic corrosion rate (CR) while considering the possible variability in CRs to assess the risk of overestimating or underestimating current criticality and future RL.