Roof Drain Floating Roof Crude Oil Storage Tank

[flatbottom]

We have a 180' diameter x 48'high crude oil storage tank with a Coflexip type roof drain hose.
The tank is in-service and one of the gaskets in the tank for the hose must be leaking because we are getting oil when we drain the roof water.
The topside of the roof is clean.
Has anybody ever done a repair to a roof drain hose/pipe while the tank is in service?
The repair would have to withstand crude oil, we were thinking something similar to a sock liner that they use on sewer piping.

 

[nash9701]

I'm having similar problem in my plant, suspect leaking from connection. Wonder if anyone have experience with onstream repair internally during tank in service.

Regards

 

[svi]

The hose type drain was thought to be more reliable than those with the swivel joint links. flatbottom, Is anything more known to confirm the flange leak. The hoses may have entangled between the legs or may have been crushed if it were to have been caught under a roof leg when the roof was landed.