Air compressor safety is very important. My air compressor, a Sanborn purchased in the mid 1980′s, recently reached the end of it’s life expectancy. I had grown complacent with draining the tank after every use and it developed a pin hole leak in the end of the tank near the bottom. This indicated a rust through condition. The tank on an air compressor is a pressure vessel. Maximum pressure on this model was set at 120 pound per square inch (psi). While not an extremely high pressure, it is certainly more than enough to do serious damage should a catastrophic failure occur. I was fortunate. The pin hole leak was the early warning that failure could be eminent. I took the unit out of service.
Avoid Repairs on Pressure Vessels
A pressure vessel is defined by OSHA as a storage tank designed to operate at pressures above 15 p.s.i.g (pounds per square inch gauge). Detailed information is available at OSHA – Pressure Vessels. While I have read accounts of people making repairs to air compressor tanks by welding holes shut or merely driving a screw into the hole, this is an extremely unsafe practice and should never be done. Resist the urge, don’t do it.
Risk of Catastrophic Failure
Pin hole leaks are an early warning of a possible catastrophic failure. When rust reaches this point the integrity of the tank is in serious question. How extensive is the rust? An ultra sound test can determine the thickness of the metal but this is probably cost prohibitive for most hobbyists. The only safe thing to do is replace the tank. Given the age of my unit, I opted to replace the compressor. I saved all the parts except for the tank. This link has conclusive evidence as to the dangers of old air compressors. I will detail the results of my search and replacement in a later post.