Project: Subsea Manifold Integrity Assessment
The potential for preferential weld corrosion in a manifold had been identified by the operator and a
Sonomatic determined that the results of the TOFD inspection were suitable for use in an Extreme Value Analysis (EVA). This indicated that the expected minimum thickness for the system would be low and the probability of a leakage condition was approaching unacceptable levels. Replacement was therefore recommended.
The Sonomatic subsea TOFD provided accurate results for use in the EVA. The analysis carried out showed that there was a high probability that the remaining thickness in the welds that could not be inspected would be considerably less than the minimum measured in the welds inspected. This provided a strong case to the operator showing that the probability of leakage was approach unacceptable levels. The integrity team was able to use this to support a case for replacement of part of the manifold.
The work carried out ensured appropriate action was taken to prevent a leak (areas of very low wall thickness were found in some of the welds on removal from service). The integrity management team were able to justify the Capex needed on the basis of the strong technical case made.