255.624 - Maximum allowable operating pressure reconfirmation: Onshore steel transmission pipelines

(a) Applicability. Operators of onshore steel transmission pipeline segments must reconfirm the maximum allowable operating pressure (MAOP) of all pipeline segments in accordance with the requirements of this Section if either of the following conditions are met:

(1) Records necessary to establish the MAOP in accordance with Section 255.619(a)(2) of this Part, including records required by Section 255.517(a) of this Part, are not traceable, verifiable, and complete and the pipeline is located in one of the following locations: (i) A high consequence area as defined in Section 255.903 of this Part; or (ii) A Class 3 or Class 4 location.

(2) The pipeline segment’s MAOP was established in accordance with Section 255.619(c) of this Part, the pipeline segment’s MAOP is greater than or equal to 30 percent of the specified minimum yield strength, and the pipeline segment is located in one of the following areas: (i) A high consequence area as defined in Section 255.903 of this Part; (ii) A Class 3 or Class 4 location; or (iii) A moderate consequence area as defined in Section 255.3 of this Part, if the pipeline segment can accommodate inspection by means of instrumented inline inspection tools.

(b) Procedures and completion dates. Operators of a pipeline subject to this Section must develop and document procedures for completing all actions required by this Section by July 1, 2021. These procedures must include a process for reconfirming MAOP for any pipelines that meet a condition of Section 255.624(a) of this Part, and for performing a spike test or material verification in accordance with Sections 255.506 and 255.607 of this Part, if applicable. All actions required by this Section must be completed according to the following schedule:

(1) Operators must complete all actions required by this Section on at least 50 percent of the pipeline mileage by July 3, 2028.

(2) Operators must complete all actions required by this Section on 100 percent of the pipeline mileage by July 2, 2035 or as soon as practicable, but not to exceed 4 years after the pipeline segment first meets a condition of Section 255.624(a) of this Part (e.g., due to a location becoming a high consequence area), whichever is later.

(3) If operational and environmental constraints limit an operator from meeting the deadlines in Section 255.624 of this Part, the operator may petition for an extension of the completion deadlines by up to 1 year, upon submittal of a notification in accordance with Section 255.18 of this Part. The petition must include an up-to-date plan for completing all actions in accordance with this Section, the reason for the requested extension, current status, proposed completion date, outstanding remediation activities, and any needed temporary measures needed to mitigate the impact on safety.

(c) Maximum allowable operating pressure determination. Operators of a pipeline segment meeting a condition in Paragraph (a) of this Section must reconfirm its MAOP using one of the following methods:

(1) Method 1: Pressure test. Perform a pressure test and verify material properties records in accordance with Section 255.607 of this Part and the following requirements:

(i) Pressure test. Perform a pressure test in accordance with the testing requirements of this Part. The MAOP must be equal to the test pressure divided by the greater of either 1.25 or the applicable class location factor in Section 255.619(a)(2)(ii) of this Part.

(ii) Material properties records. Determine if the following material properties records are documented in traceable, verifiable, and complete records: diameter, wall thickness, seam type, and grade (minimum yield strength, ultimate tensile strength).

(iii) Material properties verification. If any of the records required by Paragraph (c)(1)(ii) of this Section are not documented in traceable, verifiable, and complete records, the operator must obtain the missing records in accordance with Section 255.607 of this Part. An operator must test the pipe materials cut out from the test manifold sites at the time the pressure test is conducted. If there is a failure during the pressure test, the operator must test any removed pipe from the pressure test failure in accordance with Section 255.607 of this Part.

(2) Method 2: Pressure Reduction. Reduce pressure, as necessary, and limit MAOP to no greater than the highest actual operating pressure sustained by the pipeline during the 5 years preceding October 1, 2019, divided by the greater of 1.25 or the applicable class location factor in Section 255.619(a)(2)(ii) of this Part. The highest actual sustained pressure must have been reached for a minimum cumulative duration of 8 hours during a continuous 30-day period. The value used as the highest actual sustained operating pressure must account for differences between upstream and downstream pressure on the pipeline by use of either the lowest maximum pressure value for the entire pipeline segment or using the operating pressure gradient along the entire pipeline segment (i.e., the location-specific operating pressure at each location).

(i) Where the pipeline segment has had a class location change in accordance with Section 255.611 of this Part, and records documenting diameter, wall thickness, seam type, grade (minimum yield strength and ultimate tensile strength), and pressure tests are not documented in traceable, verifiable, and complete records, the operator must reduce the pipeline segment MAOP as follows:

(A) For pipeline segments where a class location changed from Class 1 to Class 2, from Class 2 to Class 3, or from Class 3 to Class 4, reduce the pipeline MAOP to no greater than the highest actual operating pressure sustained by the pipeline during the 5 years preceding October 1, 2019, divided by 1.39 for Class 1 to Class 2, 1.67 for Class 2 to Class 3, and 2.00 for Class 3 to Class 4.

(B) For pipeline segments where a class location changed from Class 1 to Class 3, reduce the pipeline MAOP to no greater than the highest actual operating pressure sustained by the pipeline during the 5 years preceding October 1, 2019, divided by 2.00.

(ii) Future uprating of the pipeline segment in accordance with the upgrading and conversion requirements of this Part is allowed if the MAOP is established using Method 2.

(iii) If an operator elects to use Method 2, but desires to use a less conservative pressure reduction factor or longer look-back period, the operator must notify the Department in accordance with Section 255.18 of this Part no later than 7 calendar days after establishing the reduced MAOP. The notification must include the following details:

(A) Descriptions of the operational constraints, special circumstances, or other factors that preclude, or make it impractical, to use the pressure reduction factor specified Section 255.624(c)(2) of this Part;

(B) The fracture mechanics modeling for failure stress pressures and cyclic fatigue crack growth analysis that complies with Section 255.712 of this Part;

(C) Justification that establishing MAOP by another method allowed by this Section is impractical;

(D) Justification that the reduced MAOP determined by the operator is safe based on analysis of the condition of the pipeline segment, including material properties records, material properties verified in accordance Section 255.607 of this Part, and the history of the pipeline segment, particularly known corrosion and leakage, and the actual operating pressure, and additional compensatory preventive and mitigative measures taken or planned; and

(E) Planned duration for operating at the requested MAOP, long-term remediation measures and justification of this operating time interval, including fracture mechanics modeling for failure stress pressures and cyclic fatigue growth analysis and other validated forms of engineering analysis that have been reviewed and confirmed by subject matter experts.

(3) Method 3: Engineering Critical Assessment (ECA). Conduct an ECA in accordance with Section 255.632 of this Part.

(4) Method 4: Pipe Replacement. Replace the pipeline segment in accordance with this Part.

(5) Method 5: Pressure Reduction for Pipeline Segments with Small Potential Impact Radius. Pipelines with a potential impact radius (PIR) less than or equal to 150 feet may establish the MAOP as follows:

(i) Reduce the MAOP to no greater than the highest actual operating pressure sustained by the pipeline during 5 years preceding October 1, 2019, divided by 1.1. The highest actual sustained pressure must have been reached for a minimum cumulative duration of 8 hours during one continuous 30-day period. The reduced MAOP must account for differences between discharge and upstream pressure on the pipeline by use of either the lowest value for the entire pipeline segment or the operating pressure gradient (i.e., the location specific operating pressure at each location);

(ii) Conduct patrols in accordance with Sections 255.705(a) and 255.705(c) of this Part and conduct instrumented leakage surveys in accordance with Section 255.706 of this Part at intervals not to exceed those in the following table:

(iii) Under Method 5, future uprating of the pipeline segment in accordance with the upgrading/conversion requirements is allowed.

(6) Method 6: Alternative Technology. Operators may use an alternative technical evaluation process that provides a documented engineering analysis for establishing MAOP. If an operator elects to use alternative technology, the operator must notify the Department in advance in accordance with Section 255.18 of this Part. The notification must include descriptions of the following details:

(i) The technology or technologies to be used for tests, examinations, and assessments; the method for establishing material properties; and analytical techniques with similar analysis from prior tool runs done to ensure the results are consistent with the required corresponding hydrostatic test pressure for the pipeline segment being evaluated;

(ii) Procedures and processes to conduct tests, examinations, assessments and evaluations, analyze defects and flaws, and remediate defects discovered;

(iii) Pipeline segment data, including original design, maintenance and operating history, anomaly or flaw characterization;

(iv) Assessment techniques and acceptance criteria, including anomaly detection confidence level, probability of detection, and uncertainty of the predicted failure pressure quantified as a fraction of specified minimum yield strength;

(v) If any pipeline segment contains cracking or may be susceptible to cracking or crack-like defects found through or identified by assessments, leaks, failures, manufacturing vintage histories, or any other available information about the pipeline, the operator must estimate the remaining life of the pipeline in accordance with Section 255.712 of this Part;

(vi) Operational monitoring procedures;

(vii) Methodology and criteria used to justify and establish the MAOP; and

(viii) Documentation of the operator’s process and procedures used to implement the use of the alternative technology, including any records generated through its use.

(d) Records. An operator must retain records of investigations, tests, analyses, assessments, repairs, replacements, alterations, and other actions taken in accordance with the requirements of this Section for the life of the pipeline.