Improved estimation of ultra-deep water pipe collapse pressures by using extreme value theory

Abstract

We examine safety margins between measured pipe collapse pressures and maximum external hydrostatic pressure exerted on pipeline on the seabed. We analyze collapse pressures measured on specimen rings cut from pipes, which are valid proxies for testing full length pipes. Our novel application of statistical models motivated by Extreme Value Theory provides a firmer basis for extrapolating collapse pressures than current practice which assumes a Gaussian distribution, and which gives over-conservative safety margins compared with our method. Our more accurate assessment of collapse pressures could give large cost savings in the manufacture of thick-walled pipe for ultra-deep water pipelines.