In Situ Verification of Pipeline Material Properties, MAOP Determination, and Engineering Critical Assessment

On July 1, 2020, the 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. Records required to reconfirm MAOP must be traceable, verifiable, and complete (TVC). Where records are not TVC for the pipeline material of construction, the owner must perform material verification. Material records required to be verified include:

• Diameter
• Wall thickness
• Seam type
• Grade (yield strength (YS), ultimate tensile strength (UTS), pressure rating of valves and flanges
• Charpy v-notch toughness values for Engineering Critical Assessment purposes.

There are multiple methods for gathering the data required to reconfirm MAOP. The preferred method is typically in-situ nondestructive methods. This methodology can be performed at opportunistic digs by qualified technicians utilizing approved tools to fill pipeline record gaps or by a prescriptive approach, such as scheduled repairs and excavations, among other methods. The prescriptive approach for each pipeline population consists of the following:

• 1 excavation per mile, or
• 150 excavations if comparable population is more than 150 miles

Alternative sampling plans can also be presented to the Regulator, provided they achieve at least a 95% confidence level that material properties used in the operation and maintenance of the pipeline are valid. This is where the use of inline inspection (ILI) tools can greatly reduce the number of verification digs needed per population of pipeline attributes.

ILI inspection is nothing new to the pipeline industry. ILI inspection runs are performed frequently to collect data on corrosion, dents, cracking, and other anomalies that affect the integrity of a pipeline. However, using sophisticated algorithms, this data can also be used to evaluate the attributes of the pipeline, including pipe grade.