Anonymous
Thanks for your reply. The thickness reduction I had mentioned was actual tube thickness, not the corrosion allowance. In fact, there was no corrosion allowance considered in design of the tubes.
We have already going ahead for replacement of fin fan tubes. For short term reliability, we have already hydrotested the fin fan tubes at 3.5kg/cm2 and bring down the fractionator column PSV set point to 3.5kg/cm2 instead of earlier 4.5kg/cm2. Our normal operating pressure at fractionator top is 2kg/cm2 and temp 116 degree C. Some time in previous operations we had encountered problem of pressure surging to 4kg/cm2 at column top due to mostly water present in our feed. our unit will be operational very shortly. You may please suggest for preventive course of action as a short term reliability.
Your further comment on the above will be appreciated.
Bipul