Welding, hydrotesting a compressor tank

[jbspeed]

depending on the age of the vessel..I have welded many "vibration" cracks in compressor tanks. Just clean the area...stop drill it and tig it. But, if the tank is an older tank, as has been brought out, there more than likely are other stress cracks that cannot be detected and in such case the tank should be replaced.

[usmcruz]

Im my experience, linear cracks develop on old tanks, probably due to the expansion and contraction of the tank on a daily basis when in operation. Old tanks are out of the question, and I wouldnt even attempt it, but I would weld cracked new tanks all day long!

[Bodybagger]

This thread and all the talk about welding pressure vessels reminded me of the Iraqi welder...

We took a pic of this guy on patrol. Sadly, you see it all the time. Yes that is a propane tank and yes he lived.

[Joe from N.Y.]

Man,
This thread makes me rethink my homemade sandblaster made from an old semi-rusty propane tank.

[nfinch86]

Joe ;
How much pressure is going to be in your's ?
I Don't think I would worry about it !

............. Norm

[nocheepgas]

Kind of off topic, but tanks and explosions made me think of an item in the news just the other day.
This kid was stealing gasoline from his uncle's truck, it was early in the morning and dark. He wasn't sure how full his gas can was getting. Being the Darwin Award Nominee that he is, he thought it would be a good idea to see how full his can was by illuminating the gas can with his cigarette lighter. This resulted in burns over 75% of his body.

[Blondie_486]

Wouldn't the proper hydro be more than the pressure it would run at? I also work in a refinery and the hydro's are always more than the service the vessel would see on a normal operating run.

That's been my experience as well. I worked at an ASME shop operating under the U,R & S stamps. We always hydro tested at well above operating pressure.

Bob,
Do you work at the refinery off Raff Rd.?

[davinci2010]

You are correct to have dirtied your shorts and ceased operation. The most dangerous thing in the world is people that base saftey on the fact that they have never seen something happen. I used to be an air compressor technician for a living. I don't have the pictures to show it but have seen the results of a ruptured tank; It was a mobile unit in the bed of a 3/4 ton truck. The failure destroyed the truck. just for details a gasoline powered compressor has a control called a pilot valve that unloads the pump and controls the engine idler. Pilot valves fail all of the time; That's why there is saftey relief valve on the tank to prevent an over pressure situation. The saftey valve had failed, and to save a couple of bucks the owner installed a pipe plug in it's place. The pilot valve failed soon after and the compressor ran until the tank ruptured. Had the owner not been 300 ft. away using a paint gun he would be STONE COLD DEAD!!! Compressor tanks are assembled using submerged arc process at the factory and hydrotested at 1.5 times max working psi. You cannot duplicate these conditions; Scrap that tank and buy an new one. Remember 175 lbs is pounds per square inch. Multiply 175 by the number of square inches in your tank. Whole new respect!

[enlpck]

You are correct to have dirtied your shorts and ceased operation. The most dangerous thing in the world is people that base saftey on the fact that they have never seen something happen. I used to be an air compressor technician for a living. I don't have the pictures to show it but have seen the results of a ruptured tank; It was a mobile unit in the bed of a 3/4 ton truck. The failure destroyed the truck. just for details a gasoline powered compressor has a control called a pilot valve that unloads the pump and controls the engine idler. Pilot valves fail all of the time; That's why there is saftey relief valve on the tank to prevent an over pressure situation. The saftey valve had failed, and to save a couple of bucks the owner installed a pipe plug in it's place. The pilot valve failed soon after and the compressor ran until the tank ruptured. Had the owner not been 300 ft. away using a paint gun he would be STONE COLD DEAD!!! Compressor tanks are assembled using submerged arc process at the factory and hydrotested at 1.5 times max working psi. You cannot duplicate these conditions; Scrap that tank and buy an new one. Remember 175 lbs is pounds per square inch. Multiply 175 by the number of square inches in your tank. Whole new respect!

Heres a couple pics: http://www.cdc.gov/niosh/face/stateface/ca/05ca010.html and http://www.railpictures.net/viewphoto.php?id=176187

[engnerdan]

Build a smoker or a grill, do not attempt to use it! I just scored a 30 gallon tank from work that started leaking, when we cut it open there was crud in the bottom almost 2 inches deep the entire length of the tank. It had been drained but the drain was off set from the middle and there was always water left in the tank.

-Dan