Testing system against cracking in severe environments

Paul Boughton

A leading independent testing groups has developed an innovative testing system for the offshore oil and gas industry.

The method developed was to combat or provide more robust test results in relation to Stress Orientated Hydrogen Induced Cracking (SOHIC). Developed by Exova’s corrosion experts, this new test will help the qualification of materials against cracking in severe environments.

SOHIC is a cracking mechanism which only affects carbon and low alloy steels in wet sour service. At least nine pipelines (over the past 20 years) have failed by due to this nature of crack and SOHIC has been evident in numerous Pressure Vessels. In addition this type of crack has been generally found adjacent to a weld, but not exclusively.

The new method involved a bespoke test rig being manufactured to Exova’s specifications which then enable pipelines to be bent and twisted to simulate the residual stress adjacent to a weld. The control and level of the loading is also incorporated meaning that Exova can create a ‘live’ environment. This now means that more robust test results are achieved which has major cost savings for the oil and gas industry.

Exova is currently providing the new service to its customers and its development has been supported by global oil and gas companies.

Dr Chris Fowler, Exova’s global director of corrosion, was the lead scientist in developing the method. He said: “We have developed the SOHIC testing system to help ensure pipeline integrity in the oil and gas industry, particularly as exploration is now entering harsher environments.

“This new testing method will give companies working in the oil and gas sector the reassurance they require in relation to pipeline management. It’s a significant step towards minimising the environment’s impact on this important infrastructure and help safeguard the provision of energy."

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