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July 2015

Assessing corrosion and erosion in pipelines

Dr. Mark Hutchinson

Mark has devised an innovative technique for assessing corrosion and erosion in pipelines that can provide clients with a much greater degree of accuracy.

Current conservatism
The current level 3 Fitness For Service (FFS) assessment is an analytical method where a section of the pipe and the metal losses are modelled and the stresses and strains obtained for the operating and test loads. To date these models have, even where accurate survey data has been available, simplified the corrosion, erosion, dents or gouges, to basic geometric forms, which tend to give approximate and pessimistic results. This typically leads to pipelines with sufficient ongoing structural integrity to be replaced.

The Xodus technique
Xodus’ technique does not deviate from this methodology but provides a higher level of detail into the geometric representation used in the computational models so that extracted stresses are more accurate. Therefore, when the stresses are assessed against the standards, there are usually lower utilisations and extended operating lives.

We expect this can deliver lower consultancy costs than traditional methods and will offer the ability to move from low level assessments through to FFS level 3 seamlessly. Ultimately, this method can deliver higher levels of confidence and nearly always lower utilisations and life extensions.