Tight flanges normally are used for connection two pipe under water without welding. Tight flange is locked to pipe by it's gripper and sealed with a internal rubber sealing. below figure shows the typical Tight flange. the gripper and seal are activated by flange bolts while tightening of flanges bolts.
This failure was strange and intricate because Tight flange was hydrotested before using .
it was unprecedented . tight flange was failed from back side!!!. it was not normal. why ? . the rubber seal was emerged. almost of bolt was broken.
the stress analysis of tight flange didn't show any failure
please pay attention, tight flange has not been made by oceaneering
it was unprecedented . tight flange was failed from back side!!!. it was not normal. why ? . the rubber seal was emerged. almost of bolt was broken.
tight flange was located in the rupture point of 4 inch pipeline.
Up to now, the reason of the failure is unknown.
I saw the bolts are nice damage and i think it is done black coating so i just suggest if we use stainless steel flange bolta because it most of time playing with water then what you say.
ReplyDeleteDIN 1434 | DIN 1435 | DIN 1436
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ReplyDeleteCould it possibly be fatigue failure of the bolts? Too high a prestress? Why are the bolts not part of the stress analysis?
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