Flange Gasket Behavior Characterization for Service in Arctic Environment

With Oil and Gas exploration and production in low temperature arctic environment, new concerns arise concerning the application of the existing design rules for these conditions. Most codes and standards for bolted flange calculation do not include specific rules concerning application at low temperature. Especially, gasket performances under low temperature are neither tabulated nor easily available from other public sources. In this context, in collaboration with TOTAL, SCHLUMBERGER and SAIPEM sponsors, the CETIM has performed a program called ARCTICSEAL to characterize the flange gasket behavior in arctic environment. The goal is to check that gasket references, commonly used by these companies, are still usable under low temperature arctic conditions without main performance loss. The test program involves mechanical and sealing tests performed on 4 gasket types (sheet fiber based, sheet PTFE based, sheet graphite based and graphite spiral wound) with both NPS 8 and NPS 16 gasket sizes. Gasket performances are determined at −60°C, after loading at −25°C. Additional test involving hot/cold thermal cycling ageing (simulation of intermittent hot process fluid in the bolted flange) have also been performed. The result shows the ability of the tested gasket references to maintain good sealing behavior in most cases. Moreover, the hot/cold thermal cycling ageing improves the sealing performances for some of the tested gasket references. Moreover, a dedicated test stand has been developed to study the behavior of NPS 8 flange connection exposed to quick heat-up after exposure to low temperature environment.