Session: 03-03-07 Feature Assessment Case Studies Cracking I

Paper Number: 134065

134065 - Key Elements and Best Practice in the Management of Circumferential SCC 

Abstract: 

Abstract

Circumferential SCC (C-SCC) is an emerging issue with which the industry has not had extensive experience. Prior experience indicates that C-SCC could be strongly correlated to high axial stress caused by geohazards, but there is an increasingly large volume of evidence showing that the majority of C-SCC is located in areas without identified geohazards. Effective management of this threat needs a fresh approach.

Most of the current industry practice and experience have been focused on axially-oriented SCC (A-SCC). C-SCC and A-SCC share some commonalities, but there are major differences. For instance, the sources and magnitude of axial stresses that are a key factor for C-SCC management are very different from those for hoop stresses. The availability and performance of ILI tools for C-SCC can also be different from those for A-SCC.

This paper covers key elements in the management of C-SCC, including:  

·       Susceptibility,

·       ILI technology for detecting and characterizing C-SCC,

·       Growth rate,

·       Relevance of conventional approaches, such as the concept of P_burst,

·       Fitness-for-service (FFS) assessment, and

·       Repair and mitigation options.

The state of the art (SOTA) and gaps in technology and understanding in those key elements are noted. For instance, the conventional understanding of a safety margin for A-SCC in the form of P_burst / MAOP is no longer a valid parameter for managing C-SCC as the hoop stress which is directly related to internal pressure is not a primary driver for the integrity of a pipeline segment with C-SCC. Instead, axial/longitudinal stress/strain is a primary driver. However, major components of axial/longitudinal stress/strain are often the result of the interactions between a pipeline and its supporting conditions. The axial/longitudinal stress/strain conditions also affect the choice of mitigation options and the safety measures of field work when mitigations are performed. With the above-described unique characteristics and SOTA in mind, effective management strategies involving data integration and strain-based assessment for risk reductions are proposed.

Presenting Author: Yong-Yi Wang Center for Reliable Energy Systems (Track Chair)

Presenting Author Biography: Dr. Yong-Yi Wang is the founder and president of CRES. He is widely recognized as a lead developer and practitioner of strain-based design and assessment technology with primary applications in geohazards management. Dr. Wang holds an S.M. and a Ph.D. from MIT in Mechanics and Materials.

Dr. Wang was the honoree of the Distinguished Lecture Series at the 2018 International Pipeline Conference, Calgary, Canada. He has authored over 180 technical papers on pipeline integrity assessment, management of geohazards, fitness-for-service (FFS) assessment of anomalies, materials, welding, and fracture mechanics.

Dr. Wang has held leadership positions in a number of standard and RP development activities, including API Standard1104, API RP 1176, and API RP 1187. He was a member of ASME B31.8 and B31.12 and active in CSA Z662.

Authors:

Yong-Yi Wang Center for Reliable Energy Systems (Track Chair)
David Warman Center for Reliable Energy Systems
Banglin Liu Center for Reliable Energy Systems
Jiawei Wang Center for Reliable Energy Systems