Inspectioneering Journal

The Pipeline Mega Rule: Pipeline Materials Positive Identification and Determination of Maximum Allowable Operating Pressure

By Russ Davis, Global MI COE Manager at MISTRAS Group, and James Guillory, Director of Engineering at MISTRAS Group. This article appears in the January/February 2024 issue of Inspectioneering Journal.


In 2020, the Pipeline and Hazardous Materials Safety Administration’s (PHMSA) revisions to 49 CFR 192 Part 1, the “Mega Rule,” went into effect. Part 1 includes pipeline material verification and maximum allowable operating pressure (MAOP) reconfirmation, and the records required to reconfirm MAOP must be traceable, verifiable, and complete (TVC). Although the rule has material verification requirements for components other than line pipe, the scope of this publication only includes line pipe material. Where records are not TVC for the pipeline materials of construction, the owner must perform material identification.  An owner must verify, at minimum ultimate, tensile strength and yield. As an example, if an owner is using an ultimate tensile strength of 52,000 in the 5L-X52 piping for MAOP calculations, piping must be verified as 52,000. Subpart 192.607, “Verification of Pipeline Material Properties and Attributes: Onshore steel transmission pipelines,” provides the records required to be verified include:

  • Diameter
  • Wall thickness
  • Seam type
  • Pipe Material Grade
    • Yield strength (YS)
    • Ultimate tensile strength (UTS)
    • Pressure rating of valves & flanges
  • Toughness values

There are multiple methods for gathering the data required to confirm MAOP, but the preferred method is to utilize in-situ non-destructive methods. This methodology can be performed at opportunity digs by qualified technicians utilizing approved tools or by a prescriptive approach (scheduled repairs, excavations, etc.).

The prescriptive approach consists of:

  • 1 excavation per mile, or
  • 150 excavations if a comparable population is more than 150 miles
Figure 1. In-situ non-destructive testing is the preferred method for gathering the data required to reconfirm maximum allowable operating pressure (MAOP).
Figure 1. In-situ non-destructive testing is the preferred method for gathering the data required to reconfirm maximum allowable operating pressure (MAOP).

Operators must define separate populations of similar segments of pipe for each combination of the following material properties and attributes: nominal wall thicknesses, grade, manufacturing process, pipe manufacturing dates, and construction dates. If the dates between the manufacture or construction of the pipeline segments exceed 2 years, those segments cannot be considered as the same vintage for the purpose of defining a population. The prescribed excavation frequency is applicable to each different population.

It is critical that companies utilize qualified technicians to perform testing with PHMSA-approved tools for data collection. Operators must develop a procedure for performing the testing necessary to collect the material properties data required to confirm MAOP and suitability for reliable service.

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Posted by Thirugnanam Jaya Prakash Narayanan on March 25, 2024
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