CALM buoy simulation with two types of chain

12 graph shows the response of buoy with lighter chain and 678 graphs shows it with heavier chain

12 graph shows the response of buoy with lighter chain and 678 graphs shows it with heavier chain

 

12 graph shows the response of buoy with lighter chain and 678 graphs shows it with heavier chain

Tight Flange strange failure

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.

 

please pay attention, tight flange has not been made by oceaneering

 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.

all bolt and nuts have certificate and sample of them was tested. 

 

the stress analysis of tight flange didn't show any failure

tight flange was located in the rupture point of 4 inch pipeline.

 

Up to now, the reason of the failure is unknown.