Session: 03-03-10 Feature Assessment Case Studies - Material Properties I

Paper Number: 134129

134129 - An Operator’s Experience of Managing the Hard Spot Threat 

Abstract: 

Hard spots are considered a manufacturing integrity threat under ASME B31.8S for managing system integrity of Natural Gas (NG) transmission pipelines. Historically, natural gas operators have experienced in-service failures due to hydrogen embrittlement (HE) and Hydrogen Induced Cracking (HIC) associated with martensitic high hardness hard spots in the body of the pipe.  Many of the hard spot incidents have been associated with A.O. Smith pipe manufactured in the 1950s.  However, recently other operators have had hard spot issues associated with other manufacturers.  Enbridge experience of managing the threat through a hard spot In-line Inspection (ILI) program is discussed in this paper. Enbridge completed hard spot ILI assessment on most of the piggable segments in its US and Canadian transmission pipelines.  Significant Hard Spot ILI mileage is baseline runs with recent mileage for recent reinspection runs.  Methodology for approval of Hard Spot ILI tools is addressed.  Metallurgical laboratory assessment of hard spot features is discussed, as well as bell hole inspection methodology.  NDE inspection practices for surface preparation, portable hardness testing and crack assessment are addressed.  Bellhole repair protocol has been discussed specific to Hard Spots, including consideration of interacting corrosion, cracks, and lamination manufacturing features. Overall ILI tool performance is discussed for both baseline and reruns from the perspective of Hard Spot sentenced features and subsequent in-the ditch validation. Tool performance is evaluated using API 1163 unity plot methodology comparing tool called features and in-the-ditch and laboratory validation data.   For further improvement of hard spot ILI technology, the value of pipe replacement samples with real hard spots is discussed with respect to ILI pull-through testing and metallurgical forensics.  Communication of hard spot characteristics with the ILI hard spot tool vendors is an important part of the improvement process for hard spot detection, characterization, and estimation of hardness.  Hard Spot length, width and proximity to other hard spots, corrosion and cracking are also important assessment considerations.

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:

Gary Vervake Enbridge
Debartha Bag Enbridge
Samuel Kindel Enbridge
Oleg Shabarchin Enbridge
Brady Bolf Enbridge