Best Practice for the Assessment of Defects in Pipelines – Gouges and Dents
Engineering Failure Analysis 12 (2005) 720–745 www.elsevier.com/locate/engfailanal Best practice for the assessment of defects in pipelines – gouges and dents
K.A. Macdonald b a,*
, A. Cosham
b
a
University of Stavanger, 4036 Stavanger, Norway
Penspen Integrity, Newcastle Business Park, Newcastle upon Tyne NE4 7YL, UK
Received 12 July 2004; accepted 13 December 2004
Available online 13 April 2005
Abstract
Oil and gas transmission pipelines have a good safety record and are a demonstrably safe means of transporting hydrocarbons. This is due to a combination of good design, materials and operating practices. However, like any engineering structure, pipelines do occasionally fail. The major causes of pipeline failures around the world are external interference and corrosion; therefore, assessment methods are needed to determine the severity of such defects when they are detected in pipelines.
Defects occurring during the fabrication of a pipeline are usually assessed against recognised and proven quality control (workmanship) limits. These workmanship limits are somewhat arbitrary, but they have been proven over time.
However, a pipeline will invariably contain larger defects at some stage during its life, and these will require a Ôfitness-for-purposeÕ assessment to determine whether or not to repair the pipeline. Consequently, the past 40 years have seen a large number of full scale tests of defects in pipelines, and the development of a number of methods for assessing the significance of defects. Some of these methods have been incorporated into industry guidance, others are to be found in the published literature. However, there is no definitive guidance that draws together all of the assessment techniques, or assesses each method against the published test data, or recommends best practice in their application.
To address this industry need, a Joint Industry Project has developed a pipeline defect assessment manual (PDAM).
K.A. Macdonald b a,*
, A. Cosham
b
a
University of Stavanger, 4036 Stavanger, Norway
Penspen Integrity, Newcastle Business Park, Newcastle upon Tyne NE4 7YL, UK
Received 12 July 2004; accepted 13 December 2004
Available online 13 April 2005
Abstract
Oil and gas transmission pipelines have a good safety record and are a demonstrably safe means of transporting hydrocarbons. This is due to a combination of good design, materials and operating practices. However, like any engineering structure, pipelines do occasionally fail. The major causes of pipeline failures around the world are external interference and corrosion; therefore, assessment methods are needed to determine the severity of such defects when they are detected in pipelines.
Defects occurring during the fabrication of a pipeline are usually assessed against recognised and proven quality control (workmanship) limits. These workmanship limits are somewhat arbitrary, but they have been proven over time.
However, a pipeline will invariably contain larger defects at some stage during its life, and these will require a Ôfitness-for-purposeÕ assessment to determine whether or not to repair the pipeline. Consequently, the past 40 years have seen a large number of full scale tests of defects in pipelines, and the development of a number of methods for assessing the significance of defects. Some of these methods have been incorporated into industry guidance, others are to be found in the published literature. However, there is no definitive guidance that draws together all of the assessment techniques, or assesses each method against the published test data, or recommends best practice in their application.
To address this industry need, a Joint Industry Project has developed a pipeline defect assessment manual (PDAM).
References: [2] Managing System Integrity for Hazardous Liquid Pipelines, API Standard 1160 (ANSI/API STD 1160–2001), 1st ed., November; 2001. [6] Manual for determining the remaining strength of corroded pipelines. A supplement to ASME B31 code for pressure piping, ASME B31G-1991 (Revision of ANSI/ASME B31G-1984) [20] Stephens DR, Leis BN. Development of an alternative criterion for residual strength of corrosion defects in moderate- to hightoughness pipe. Proceedings of the third international pipeline conference (IPC 2000), Calgary, Alberta, Canada, vol. conference on offshore and polar engineering (ISOPE 2000), Seattle, USA; 2000.