Session: 03-03-05 Feature Assessment Case Studies Cracking Session II

Paper Number: 132435

132435 - Challenges to Manage Short But Deep Crack-Like Features 

Abstract: 

A near through-wall axial crack flaw was identified in the 1950s vintage flash welded 24-inch liquid pipeline in the ditch. This feature was assessed using Magnetic Particle Testing (MT), encoded Phased Array Ultrasonic Testing (PAUT) and Time of Flight Diffraction (TOFD). It was identified to be a stacked flaw with a total axial length of 23mm, including external crack-like with 5.7mm depth and internal lack of fusion with 2.5mm depth making it 88% deep based on local wall thickness of the weld. Because of its significant depth, this feature was extracted by coupon cutout for further examination. Some other operators have also discovered short but deep crack features in operating pipelines. These features can be either through-wall or near through-wall and are challenging to detect and size with in-line inspection (ILI) and NDE technologies. These short but deep penetrators are typically a leak threat but the consequences of a leak in High Consequences Area (HCA) can be significant depending on the location.

Before the destructive testing, Enbridge took the opportunity to invite three additional NDE vendors for sizing and to apply Eddy Current Array (ECA) advanced technology as part of a sizing accuracy verification between ILI tool and in ditch NDE. All additional NDE vendors were invited to size this feature with PAUT and TOFD in their shops following the Enbridge requirements. This was also extended to the ILI company which had their field technician included in the validation. 

This paper will show a detailed comparison in feature sizing across all four NDE vendors and their subjective results. The paper will include screen captures of the data acquisition, sizing methodologies utilized, and a comparison between TOFD and PAUT amplitude sizing and the true macro data taken from the cross-sectioning.

On the other hand, these short but deep features are also challenging for ILI to detect and accurately size. In a collaborative project with NDT Global, the next generation ILI crack tool, Proton, was developed and validated in the 2017-2022 timeframe. Though the development did not specifically target short but deep crack-like features, the multi-angle ultrasonic technology does expand the capability of in-line inspection tools to detect and size these short and deep features.

This study provides a guideline on how to work with ILI vendors to leverage the acquired data from both ILI and field results to implement non-standard analysis procedures to address these outside specification features. The main goal is to use this data to improve the detection and sizing of short and deep crack features which may threaten pipelines. This paper provides a blueprint and guidance for risk management of such threats, tying together the various risk elements and emerging risk abatement strategies.

Presenting Author: Mengshan Yu Enbridge

Presenting Author Biography: Mengshan Yu has 13-years experience in pipeline integrity with both academic and industrial background. He works with Enbridge as Senior Engineer to manage the crack, corrosion and deformation threats on the assigned pipelines since 2021. Prior to Enbridge, Mengshan worked with Plains Midstream Canada as an Integrity Engineer and with Stantec Consulting as a Junior Integrity Specialist. He got his Ph.D. Degree from University of Alberta in 2015 with thesis on near-neutral pH SCC and his Bachelor Degree from Chonging University, China, in 2009.

Authors:

Mengshan Yu Enbridge
Axel Aulin Enbridge
Vitaly Vorontsov Enbridge
Lyndon Lamborn Lamborn Engineering Inc.
Jordi Aymerich NDT Global
Rogelio Guajardo NDT Global