My tank has developed a couple pin holes in it. I have been told to never repair these tanks because of explosion reasons. I can't find another tank right off either. So is it a major no no to patch these or not? Just wanting to here from others that know.
Just one pin hole in the steel shell of the air tank indicates extreme internal degradation of the steel. The fact that you have noted "a couple of pin holes" indicates the structural integrity of the tank is compromised. Your tank is telling you it's sick, and I don't know that a patch would be a suitable cure, or a safe one either. What style/size tank do you have? I recently purchased a replacement 30 gal tank online for a little over 300 dollars.
This compressor air tank failed due to improper maintenance. Its tank water was not drained on a regular basis and the bottom corroded. Since this compressor was in someone's home garage, it was not required to be inspected under current Minnesota laws. No one was injured when the tank failed. The tank was not built to ASME code and not registered with the National Board. The drain valve on the tank was removed, probably because it was leaking, and replaced with a plug. The accumulation of water in the vessel caused severe corrosion and thinning of the metal on the bottom of the tank. Ultrasonic thickness testing revealed a thickness of .070 inches. At this thickness the tank should never have been allowed to be pressurized. The safety valve was set at 140 psi and the pressure controls were assumed to be working properly. The purchaser brought home his new treasure, put it in his garage and plugged it in. When the pressure in the tank reached about 100 psi, the tank ruptured and flew across the garage. Luckily, nobody was injured. Unfortunately has happened many times. If you do a Google Image search for air compressor explosions a lot of these happen. Beware some images are awful graphic showing fatalities as a result of an explosion. I found that another cause of air compressor explosions result from oil getting into the compressor. I have one with worn piston rings and I am now motivated to do an overhaul.
In NC the department of labor has a boiler safety bureau that inspects once a year on air compressors tanks, they do not do homeowner. I would not due a repair even for myself on a tank due to safety, pull the motor and pump, drill a hole 1/2" and hit it with a sledge hammer in the center and take it to the scrap man. Those tanks can be bought at a fair price and depending on the compressor, it may be cheaper to just replace it. You would have to take it to a welder/boiler/pressure ves/ then reinspected to be sure. Like willie59 and tinkerer have pointed out, pin hole may be just the start of a pic like tinkerers.
I see , kind of like a water heater with a plugged relief valve. Mucho boomo.
Mucho boomo. I like the lingo. I think I would say screw the repair idea. Screw the scrap idea. Drill a self tapping screw into the pinhole, put it in a field, get a long house and pump it full of acetylene. Then shoot it with a fifty cal. Trust me, this is much more fun than any of the advice given so far, and you definitely don't want to continue using it as a compressed air tank. It's a no brainer, and it's like you are saving your own life man.