By R. Lee Vail

Each pipeline has a regulatory maximum operating pressure: Maximum Allowable Operating Pressure (“MAOP”) for gas pipelines and Maximum Operating Pressure (“MOP”) for hazardous liquids pipelines. See 49 C.F.R. 192.619(a) and 49 C.F.R. 195.406(a). The Pipeline and Hazardous Materials Safety Administration (“PHMSA”) recently issued an Advisory Bulletin requiring that owners and operators “assure that all MAOP and MOP are supported by records that are traceable, verifiable, and complete.” See 77 Fed. Reg. 26822, 26823 (May 7, 2012).

Several technical considerations go into establishment of MAOP/ MOP including the design pressure of the weakest element in a segment, pressure testing, and maximum safe pressure considering specific pipeline history. However, pre-1970 pipelines may establish MAOP/MOP based on pre-1970 operating data. See 49 C.F.R 192.619(a) and 49 C.F.R. 195.406(a). Owners and operators of qualifying pre-1970 pipelines do not have to pressure test pipeline segments nor consider design information when establishing MAOP/MOP.

However, where MAOP/MOP records for a specific method are not traceable, verifiable, and complete, the owner/operator must “rely on another method as allowed in 49 C.F.R. 192.619 or 40 C.F.R. 195.406.” See 77 Fed. Reg. 26822 and 76 Fed. Reg. 1504, 1506 (Jan. 10, 2011). As such, MAOP/MOP developed using non-traceable, non-verifiable, or incomplete pre-1970 operating pressure data would not be allowed; MAOP/MOP must be developed by another method. In effect, the grandfathered segment would no longer be grandfathered. Further, given the forty plus years since construction, compliance options may be limited as required design information may no longer exist (assuming it ever did).

The referenced Advisory Bulletin establishes guidelines for information that support MAOP/MOP determinations, including “the highest actual operating pressure to which the segment was subjected” prior to 1970. 40 C.F.R. 192.619 (a)(3). This historical operating pressure data must be traceable, verifiable, and complete.

  • Traceable records can be traced back to the original source document. Transcribed documents require further verification.
  • Verifiable records can be confirmed by other records such as contracts for pressure tests that are confirmed by pressure charts or fields log.
  • Complete records must be signed and dated.

The implication of the guidance is that owners and operators must have original documents containing pre-1970 operating pressure data for grandfathered pipelines (or data that can be verified to represent pre-1970 data) that is signed and dated. Without sufficient data to establish MAOP/MOP using historical data, owner/operators must establish MAOP/MOP by other allowed methods.

PHMSA is also planning revisions to the Annual Report form for Gas Transmission and Gathering Lines (PHMSA F 7100.2-1) to facilitate collection of information regarding methodology used by the owner/operator to determine MAOP of gas transmission pipelines. 77 Fed. Reg. 22387, 22388 (Apr. 13, 2012). Under the same initiative, the Annual Report will require disclosure of non-pressure tested and “non- piggable” pipeline segments. To the extent it has not already been done, operators and owners of pipelines should review their records supporting their MAOP and MOP determinations, consistent with this recent guidance.