Home › Forums › Coking › hydrotest pressure of fractionator ovhd finfan cooler › RE: hydrotest pressure of fractionator ovhd finfan cooler
Hi! It appears from your post that the air cooler HEADER BOXES have lost approximately 50 percent of their original corrosion allowance of 3 mm. If this is the case, there is no concern since at least 1.5 mm of corrosion allowance is still available (note that rigorous engineering calculations performed today might find that more than 1.5 mm corrosion allowance still remains). If the TUBES have lost approximately 50 percent of their original wall thickness of 3 mm, I would proceed to hydrotest the air cooler at its original test pressure of 6.75 kg/cm2, plug off any leaking tubes, return the air cooler to operation, and follow-up with ordering a replacement tube bundle. A tube wall thickness of 1.0 to 1.5 mm is normally considered the absolute minimum required for SHORT-TERM reliability. Reducing the maximum operating pressure of the distillation column and the air cooler will not provide any real increase in remaining life of the air cooler since the operating pressure is so low to begin with. Good luck!