# Crack in air tank



## abrasivemike (Jun 24, 2013)

I'm considering a good deal on a 5HP compressor. The owner tells me that one of the legs got caught in transport and a small crack developed. He says there is a very small leak at the crack, but a leak is NG. Does anyone have experience in welding a small crack in an air tank? What would be the best process to use?  Thanks, Mike


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## Tony Wells (Jun 24, 2013)

Most people would advise against welding an air tank or receiver. ASME code, followed carefully, will be an acceptable repair in most cases, but should be pressure tested by an accredited facility. Welding pressure vessels is probably best left to ASME code welders. Or at least consult one about the repair.


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## samthedog (Jun 24, 2013)

Unless you are going to get it fixed through a professional and accredited welder, steer clear. I work in an environment that deals with pressure vessels and gas / fluids. 100 PSI is more than enough to kill you if things go south on a dodgy weld.

Paul.


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## GK1918 (Jun 24, 2013)

I cant count how many truck air tanks I repaired over the years.  Some were drilled and welded on a extra threaded fitting, some a small rust area,
being welded in the first place anyways and trucks run usually 120-125lbs I never had one come back.  So I do not know, however I did get a
natural gas pipe cert. back when I could see things lol


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## Gary Max (Jun 24, 2013)

Think about this--- the inside of the air tank is rusted---- rust and welds really don't work well together.


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## cathead (Jun 24, 2013)

Consider finding another tank somewhere maybe......


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## Rbeckett (Jun 24, 2013)

I would opt for a new tank.  Welding on a pressure vessel of unknown age and corrosion is asking for a major failure.  If the metal was fatigued enough to crack it is compromised too much to safely weld too.  A new approved tank should be available very cheap and you can opt for a larger tank for more volume.  

Bob


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## TOOLMASTER (Jun 24, 2013)

http://www.mcmaster.com/#steel-compressed-air-tanks/=nc07os


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## tripletap3 (Jun 24, 2013)

Did I miss something Mike?  Fennimore Wisconsin is not in Montenegro as I am pretty sure I have seen that on the map while driving to Madison WI. :LOL: Anyway. The only responsible advice anyone could give you is to NOT weld on a pressure vessel unless you are trained to do so. That being said I have seen a few welded successfully. :whistle:


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## Ulma Doctor (Jun 24, 2013)

i'm not proud to admit, but i have sinned it seems.
i have welded multiple pressure vessels for friends as well as Getnr' Done NOW in Business
I worked for a drayage company for a little while as a diesel mechanic.
As soon as the Brass found out i could weld...tag!!!
i got every rusted, crusted, frozen, broken, mangled piece of excrement they could throw at me.
i welded tanks of all sorts for them, even did my own crude caged pressure testing. 
we had a tank for checking newly repaired truck tires, i'd sink the tank when i could and take em up to pressure in steps.
i learned it was best to drill the ends of the cracks, weld the cracks, grind flush and then weld large patches whenever possible to maximize the weld surface area around the repair you just made, to prevent it coming back.
yes, the process was slow, dirty,and time consuming. but i had a 100% success rate.
must have been doin' something right or wrong dependent on your perspective.


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## sniggler (Jun 25, 2013)

How old is the tank? What condition is it in? If it is old and rusty i might pass, but if it is clean and solid i would probably repair it.

Ulma Doctor has it right drill the ends. You said the crack is at the foot of the tank so if the foot is welded to tank or to a plate or angle welded to the tank you have that to build the weld off. Welder skill level has a lot to do with this but i would go straight at it with 3/32 7018 (bare wire mig would be fine too) making sure i had zero under-cut and good tie in on the tank surface. Welding hot on thin material is a journeyman's skill. 

The premium repair would be a tig weld with argon drifted into the tank to displace the air in the tank during welding and the crack opened up clean the inside surface of the tank. 

I could really use a sweet deal on a 5hp compressor about now. I am not recommending anyone weld on pressure vessels just saying how i would do it

Bob


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## abrasivemike (Jul 2, 2013)

tripletap3 said:


> Did I miss something Mike?  Fennimore Wisconsin is not in Montenegro as I am pretty sure I have seen that on the map while driving to Madison WI. :LOL: Anyway. The only responsible advice anyone could give you is to NOT weld on a pressure vessel unless you are trained to do so. That being said I have seen a few welded successfully. :whistle:


As far as the cracked tank goes, I'm searching for a replacement first. As  far as Fennimore goes, you're right, it's about 60 miles west of Madison WI but since I moved here 17 years ago I find only about 20% of the population even know about the country of Montenegro- the home of my ancestors so I put it in print when I can. Thanks to all for the replies to my question.              Abrasivemike- Mike Chulafich


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## savarin (Jul 3, 2013)

Ulma Doctor said:


> i learned it was best to drill the ends of the cracks, weld the cracks, grind flush and then weld large patches whenever possible to maximize the weld surface area around the repair you just made, to prevent it coming back.



Done quite a few like this and never had a problem.


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