Session: 03-03-06 Feature Assessment Case Studies Cracking II

Paper Number: 133979

133979 - An Operator’s Experience of Managing the Threat of Axial SCC 

Abstract: 

Stress Corrosion Cracking (SCC) is one of the three time-dependent integrity threats classified under ASME B31.8S for managing system integrity of Natural Gas (NG) transmission pipelines. Enbridge experience of managing SCC threat through the Electromagnetic Acoustic Transducer (EMAT) In-line Inspection (ILI) program is discussed in this paper. Enbridge has run more than 9000 miles of EMAT tool in its US and Canadian transmission pipelines.  Prior to running EMAT on the SCC susceptible lines, the SCC threat was managed using SCCDA for low or moderate lines.  Hydrostatic testing was performed for high risk segments and segments with a history of SCC.  The systems are comprised of large diameter vintage pipelines with some operating under Grandfathered high operating stress conditions.  Coating conditions include vintage coal tar enamel, asphalt, pipe body tape and shrink sleeves.  Significant mileage is baseline runs and subsequently recent mileage for reinspection. Overall EMAT tool performance is discussed for both baseline and reruns from the perspective of initial EMAT callouts and subsequent in-the ditch validation of EMAT features. Both high pH and near neutral pH SCC, confirmed in the ditch, and subsequent metallurgical laboratory assessment, has been discussed for Enbridge’s US and Canadian assets. Bell hole inspection verification of EMAT features was performed with Phased Array UT (PAUT) and Magnetic Particle Inspection (MT).  Tool performance has been discussed leveraging Enbridge’s vast mileage of EMAT data using API 1163 unity plot methodology comparing tool called features and in-the-ditch and laboratory validation data.  Only data for features that meets EMAT vendor detection criteria were used for unity plot assessment.  Enbridge’s Bellhole inspection and repair protocol has been discussed specific to EMAT related digs for managing the SCC threat, and the process for reporting results back to the EMAT vendor were addressed.  Vendor feedback and collaboration with pipe replacement samples with SCC are considered critical steps for the continual improvement of the SCC IMP program and EMAT performance.

Presenting Author: Debartha Bag Enbridge

Presenting Author Biography: Debartha Bag, Engineering specialist Metallurgist. Started with Enbridge in Fall 2021, in Pipeline Integrity Engineering Department. Primarily involved in managing different threats involving SCC, hard spot and SSWC, along with providing support for field engineering, repairs, and metallurgical investigation.

Holds Master's Degree in Materials Engineering from Queen's University in Kingston Canada. Overall, more than 12 years of industrial experience in oil& gas and petrochemical industry in Materials Engineering, Corrosion and Asset Integrity.

Authors:

Debartha Bag Enbridge
Hena Rehman Enbridge
Gary Vervake Enbridge
Gordon Fredine Enbridge