Riser Flange Failure Investigation
Swivel flanges failed offshore during leak testing, PSI Engineering were asked to investigate the root cause of failure. The investigation found that there was rotational movement at the flange hub interface, this caused significant galling. The galling deposits forced the flange faces apart enough to unload the metal gasket and cause leakage. The flange manufacturer had assumed a static friction of 0.65 for their design calculations, when tested this value was found to be around 0.25 to 0.3.
By simulating the installation conditions, we were able to determine a set of start up and operating conditions that would prevent leakage. PSI Engineering then developed a swivel flange design with significant torque resistance over standard swivel flanges.