This paper describes the activities and stages completed as part of the Integrity Management Program for SCC in the natural gas system of Transportadora de Gas del Norte (TGN-Argentina) which started in 2000. This document focuses in a pipeline section of the system, which suffered an in-service failure in 2002 due to high pH SCC.
This event triggered a series of activities, whose results are detailed in this paper. These activities involved soil analysis to determine the susceptibility to develop SCC along the system pipelines. For susceptible sections, the program included hydrostatic testing to levels of 100% and 110% of SMYS followed by replacement of degraded coating.
The paper also details the experience in the use of new internal inspection tools with EMAT technology. The capability of the EMAT tool to detect and size SCC defects and the possibility of discriminating between SCC colonies that have been recoated and those that may still be active due to degraded coating is discussed. Finally, the severity of SCC cracks detected by in-line inspection is assessed using API 579 methodology, and the feasibility of using this assessment results to determine the critical SCC defect sizes for detection by ILI tools is analyzed.