At the time of a recent maintenance shutdown, cracking was discovered in the repads and parent material in the vicinity of several nozzles along the bottom of two in-situ production treater vessels. Some of the cracks were reported to be through-wall. The vessels were commissioned in 2009 and had been in service for about 13 years before the cracks manifested as through-wall.
Product Number:
51323-19173-SG
Author:
Duane Serate, Simon Yuen, Yashar Behnamian, Jeffrey Venezuela
Publication Date:
2023
$0.00
$20.00
$20.00
Over the last few years, an intergranular stress-corrosion cracking (IGSCC) mechanism has been observed for carbon steel pipelines and piping, particularly in in-situ thermal upstream production. All the cracks manifested on the bare (uncoated) outside diameter (OD) surface of the steel, and all were associated with wet mineral wool insulation. Common features include an operating temperature between 70°C and 160°C, intergranular cracking morphology, and exposure to wet mineral wool insulation with vintage post-2003.
Recently, a similar IGSCC was observed in pressure vessel grade A516 Gr 70N steel. The potential of having this mechanism manifest in pressure vessels is of some concern, as the span of susceptible equipment goes beyond upstream production assets but to the larger oil and gas industry that includes upgrading, refining, terminals and distribution, and perhaps extending to other industries where the conditions listed above exist.
This paper summarizes the investigation of the external IGSCC found on two carbon steel pressure vessels, with the intent of increasing the awareness of the industry with this new damage mechanism.