MAOP Reconfirmation for a 20 Inch Gas Pipeline Using the ECA Method and Enhanced ILI

Abstract

Abstract In light of the revised Federal Pipeline Safety Regulations, active from July 1, 2020, operators of gas transmission pipelines are faced with the task of reconfirming pipeline MAOP in a prescriptive set of circumstances. This requirement is defined in section 192.624 of 49 CFR 192. Louisville Gas & Electric (LGE) is operating a pipeline with an MAOP established using a combination of partial and full traceable, verifiable and complete (TVC) documentation and the ‘grandfathering’ clause defined by 192.619(a)(3). LGE has developed a plan and embarked on the process of reconfirming the MAOP using Method 3 – Engineering Critical Assessment (ECA). 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, Class 3 and Class 4 locations, and newly defined MCAs (per 192.3) 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 via method 3 is detailed in clause 192.632. A critical element of an ECA per method 3 is the implementation of various ILI technologies to detect, identify, and size target threats. ROSEN provided an enhanced program of ILI including technologies to assess material properties, and crack-like/metal-loss anomalies. A critical aspect of method 3 is the use of appropriate material properties in the ECA. The operator deployed the RoMat PGS ILI system as the foundation for material property verification process to fulfill the requirements of clause 192.607 of 49 CFR 192, a requirement to establish ‘unknown material properties’. This paper describes the comprehensive work performed by the partnership of ROSEN and LGE to establish and fulfill the MAOP reconfirmation process. Such a large ILI program is a significant undertaking considering the associated data-integration, operational and engineering details that have to be addressed. This paper presents the methodologies used for each stage of the ECA process and how the ILI and material verification results were used to determine predicted failure pressures and remaining life. By satisfying the regulations, the operator has established a process to manage pipeline integrity, reduce risk, and reconfirm MAOP.