In light of the revised Federal Pipeline Safety Regulations, active from 1 July 2020, operators of gas transmission pipelines are faced with the task of reconfirming the pipeline MAOP in a prescriptive set of circumstances. This requirement is defined in section 192.624 of 49 CFR 192. An operator of a gas transmission pipeline is operating with an MAOP established using a combination of TVC records and the so-called ‘grandfathering’ clause and has developed a plan and embarked with the process of reconfirming the MAOP using Method 3 – Engineering Critical Assessment. The pipeline is 20 inch diameter and predominately 0.25 inch wall thickness. It was originally constructed from vintage ERW pipe circa. 1960 to 1970 and is 29.86 miles long. There have been no reportable incidents on the line. There are various HCAs, MCAs, Class 3 and Class 4 locations along the line. The approach taken by the operator is to reconfirm the MAOP along the full pipeline length to cover the possibility of class location changes in the future.  MAOP Reconfirmation method 3 is covered in clause 192.632 of 49 CFR 192. A critical aspect of this project was the implementation of various ILI technologies to detect, identify and size anomalies. ROSEN provided a program of enhanced ILI including technologies to assess crack-like and metal-loss features. A critical aspect of method 3 is the use of appropriate material properties in the ECA. The operator used the RoMat PGS ILI service as the foundation for material property verification in line with clause 192.607 of 49 CFR 192. This paper describes the comprehensive work performed by the operator and ROSEN to establish the MAOP reconfirmation process. Such a large ILI program is a significant undertaking with associated operational and engineering issues that have to be considered. This paper presents the methodologies used for each stage of the process and how the ILI results and material verification were used in feature assessments to determine predicted failure pressures and remaining life. By satisfying the regulations, the operator has established a process to manage the pipeline integrity effectively and reduce risk.


Maop Reconfirmation for a 20 Inch Gas Pipeline Using the Eca Approach and Enhanced Ili

Division / Sponsors: 
Pipeline Systems Division

Paper Proceedings: https://asmedigitalcollection.asme.org/IPC/IPC2020/volume/84447

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