Dear all,
We operate a Carbamate Condenser to reduce the temperature of recycle carbamate from 180 C to 158 C. Condensate is fed on the shell side to generate steam at 3.5 kg/cm2.g. There is a PSV installed on shell side with set pressure 5.5 kg/cm2. A process upset caused 20 kg/cm2.g (superheated) to get into the shell side of the exchange and popping of the PSV. The pressure inside the vessel was reduced to 2 kg/cm2 but the seat didn't revert back. It was reverted back manually using a hand jack.
I am trying to find the root cause of the SEAT NOT REVERTING BACK. One of the probable causes that we are thing is the probable thermal expansion of seat metal part and getting stuck inside but the clearance between the cylinder and moving seems to be a bit larger that doesnt't justify this reason. What could be the other probable causes of this phenomenon?
Info:
Spring Material: CS Phosphatized
Test Spring pressure: 5.5 kg/cm2.g
Max. Overpressure: 10% of set pressure (5.5 kg/cm2.g)
Thanks.