We have replaced the Hahn & Clay hydraulic unheading system with Delta Valves bottom unheading devices. A transition spool was placed between the Delta Valve and the Coke Drum, that transition spool has a lateral nozzle which is the inlet nozzle (Single feed). Stud assembly includes Belleville washer design (live load) and Hydraulic Torque Wrenches were used for tightening the studs. The gasket that is being used is a corrugated metal graphite covered (1” wide).
After few cycles after star up, leaks were observed on the flange between the transitions spool and the drum (all six drums). The first leak normally occurs during quenching and always is located opposite to the inlet line.
We have tried to retorque after one cycle without success, studs and nuts were seized.
We would like to know if someone else has had this problem and what has been done to solve it. We really appreciate any comment or directions you can provide.
Regards, Stuart Lugo
The Petrozuata Upgrader (Venezuela) had that same problem. A few months after the installation of Delta Valves and bolted transition spools with side entry, the joint between the transition spool and the coke drum began to leak.
Last year the gasket was replaced with one manufactured by Chesterton, with good results, so far.
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