High-temperature and high-pressure flange leakage in residue hydrogenation
Thread Content
During the shutdown of the residue hydrogenation unit, leakage occurred at the high-temperature and high-pressure flanges as the temperature and pressure decreased. Experts, please analyze the reasons. Material 321, operating temperature 375°C, pressure 17 MPa. Recently, when the operation was stopped and the temperature was reduced to 220°C at 7 MPa and 45°C at 4 MPa, leaks occurred in each of the two flanges respectively. There have been a few leaks before as well.
What is the material of the flange stud? How long has it been running? It may be related to fastener stress relaxation
Where did the leakage occur? Is it due to pressure reduction and contraction, causing leakage at the gaskets and bolts?
The operating time for this device should be relatively long; the large top flange makes it easy for stress relaxation in the fasteners and deformation of the octagonal gaskets to occur, leading to seal failure. After removal, use red dye to inspect the sealing surface, and also check the condition of the gasket.
The flange leakage is likely closely related to the fast rate of temperature and pressure drop in the system.