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Leak in spiral weld in a 16 inches gas pipeline

Abstract

This paper discusses a failure analysis after a leak in the spiral weld of a 16 inches natural gas pipeline, in service since 1974. The leak was the result of the coalescence of two different defects, on each surface of the pipe wall, located in the center of the inner cord of the helical DSAW weld. Fractographic and metallographic studies revealed that the leak was a combination of three conditions. During fabrication of the pipe, segregation in grain boundary grouped in mid weld. During service, these segregations underwent a process of selective galvanic corrosion. One of these volumetric defects coincided with a tubular pore in the outer weld. Pigging of the pipeline in 2005 for cleaning likely contributed to the increase of the leak flow, when eliminating corrosion product plugs. Although these defects are likely to repeat, fracture mechanics shows that a defect of this type is unlikely to cause a blowout. (author)
Authors:
Fazzini, Pablo G; Bona, Jeremias de; [1]  Otegui, Jose L [2] 
  1. GIE S.A., Mar del Plata (Argentina)
  2. University of Mar del Plata (Argentina)
Publication Date:
Jul 01, 2009
Product Type:
Conference
Report Number:
ETDE-BR-1411
Resource Relation:
Conference: Rio pipeline 2009 conference and exposition, Rio de Janeiro, RJ (Brazil), 22-24 Sep 2009
Subject:
42 ENGINEERING; PIPELINES; NATURAL GAS; LEAKS; FAILURES; WELDING; SEGREGATION; SLAGS; FRACTURE MECHANICS
OSTI ID:
21319879
Research Organizations:
Instituto Brasileiro de Petroleo, Gas e Biocombustiveis (IBP), Rio de Janeiro, RJ (Brazil)
Country of Origin:
Brazil
Language:
English
Other Identifying Numbers:
TRN: BR1003588
Availability:
Commercial reproduction prohibited; OSTI as DE21319879
Submitting Site:
BR
Size:
9 pages
Announcement Date:
Jul 02, 2010

Citation Formats

Fazzini, Pablo G, Bona, Jeremias de, and Otegui, Jose L. Leak in spiral weld in a 16 inches gas pipeline. Brazil: N. p., 2009. Web.
Fazzini, Pablo G, Bona, Jeremias de, & Otegui, Jose L. Leak in spiral weld in a 16 inches gas pipeline. Brazil.
Fazzini, Pablo G, Bona, Jeremias de, and Otegui, Jose L. 2009. "Leak in spiral weld in a 16 inches gas pipeline." Brazil.
@misc{etde_21319879,
title = {Leak in spiral weld in a 16 inches gas pipeline}
author = {Fazzini, Pablo G, Bona, Jeremias de, and Otegui, Jose L}
abstractNote = {This paper discusses a failure analysis after a leak in the spiral weld of a 16 inches natural gas pipeline, in service since 1974. The leak was the result of the coalescence of two different defects, on each surface of the pipe wall, located in the center of the inner cord of the helical DSAW weld. Fractographic and metallographic studies revealed that the leak was a combination of three conditions. During fabrication of the pipe, segregation in grain boundary grouped in mid weld. During service, these segregations underwent a process of selective galvanic corrosion. One of these volumetric defects coincided with a tubular pore in the outer weld. Pigging of the pipeline in 2005 for cleaning likely contributed to the increase of the leak flow, when eliminating corrosion product plugs. Although these defects are likely to repeat, fracture mechanics shows that a defect of this type is unlikely to cause a blowout. (author)}
place = {Brazil}
year = {2009}
month = {Jul}
}