New test method investigates materials cracking
Exova has developed a new test method to combat stress orientated hydrogen induced cracking (SOHIC).
LONDON – Exova has developed a new test method to combat stress orientated hydrogen induced cracking (SOHIC). It should assist qualification of materials against cracking in severe environments.
Development has been supported by numerous oil and gas companies.
Dr. Chris Fowler, Exova’s global director of corrosion, said: “We have developed the SOHIC testing system to help ensurepipeline integrity in the oil and gas industry, particularly as exploration is now entering harsher environments.”
SOHIC is a cracking mechanism which only affects carbon and low alloy steels in wet, sour service. Over the past two decades, according to Exova, at least nine pipelines have failed as a result, and SOHIC has also been detected in pressure vessels. This type of crack can also appear close to welds.
The new method involved designing a test rig that allows pipelines to be bent and twisted to simulate the residual stress adjacent to a weld. Additionally, the control and level of the loading is incorporated to create a “live” environment, which Exova claims has led to more robust test results with resultant cost savings to the industry.