Peter Carr, Global Leader of Risk Management and Ian Nash, Global Leader of Subsea Pipelines presented their paper Eliminating the Precommissioning Hydrotest for Deepwater Gas Pipelines in June 2014 at the International Offshore and Polar Engineering Conference, in Busan, Korea.
The paper describes the development of a preliminary case for using alternative integrity validation (AIV) for deepwater gas pipelines in place of the traditional precommissioning hydrotest. The features of an AIV program that would compensate for lack of a hydrotest are identified. Measures to prevent or detect linepipe damage or deterioration during transportation and installation are discussed. Quantitative reliability analysis methods are explored to compare the effectiveness of AIV and the traditional hydrotest in exposing the types of flaws typically found in girth welds. Recommendations are made for the collection of data on flaw frequencies and size distributions, as lack of these data is currently an impediment to the application of probabilistic models.