Relevant person of the WXSC and two engineers of KOSO (Wuxi) valve went to ESL India Oxygen plant for service.
Main problems
FCV 1201C model control valve used in main line can not be opened completely under the instructions.
Operation
According to the description of site engineers, KOSO engineers speculated that the valve could not be opened completely due to the lack of maintenance of pneumatic actuator and damage of internal seals.
Since the oxygen plant had not shut down, and the pipeline pressure was very high, the valve can not be disassembled directly. In the meantime, the steel plant required the oxygen plant got back to run two days later.
The only way was to remove the actuator only. So the engineer asked for to cut out a set of thrust block to fix the rod of control valve to prevent the valve disc moving from pipeline pressure.
After removing the actuator, KOSO engineers disassembled the actuator on site and found that the O-rings had damaged already, also the cylinder inner surface had been outworn. The repaired actuator installed back after replaced all the O-rings, repolish the cylinder inner surface and applied new lubrication oil.
Final result
After repaired, the control valve can be opened completely by the given signal.
Maintenance suggestion
Koso engineers recommended to replace the O-rings of actuator every two years to ensure the use of control valve.