compressor question?

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i bought a 60 gal upright with a 184t-5hp with a 3 cyl 2 stage pump.  Motor and pump were brand new.  got it for 250 off craigslist.now, the problem, the motor and pump are sitting on my old compressor while i attempt to fix the 60 gal tank.It is missing one of the legs, and when i pulled the bottom water drain valve out, some nasty chunky peices of rust came out.So i cut the bottom of the tank off with a sawzall, right through the center of the factory weld.  What was left on the bottom of the tank was not pretty, lets just say i removed it in chunks with a slag hammer.Ive fabbed up a new backup ring, but before i weld it back together and repaint it, i was thinking maybe i should paint the inside of the tank with like rustoleum?the problems i foresee would not being able to get the inside of the tank cleaned properly for the paint to correctly adhere, as well as the paint flaking off from the heat of welding...think i should just weld it up, or try and paint the inside first?the ultimate plan is to plum both the compressor together into a manifold system for tons of air during sandblasting and when buddies come over to help me sand cars for paintwork.sorry for the long post, i cant sleep
Reply:no no paint after you weld it if you paint first the will paint mess up your weld and you will still have a spot with out paint.weld first let cool poor in paint roll on floor drain out leftover paintlet dry,put back in serviceChuckASME Pressure Vessel welder
Reply:If your big worry is about the paint sticking is do to surface rust, you could sandblast the interior before you weld it back together. If you are concerned about oil on the metal I'd wash it with simple green and then preasure wash or rinse well and let dry. You may end up with a bit of "flash rust" as the surface dries bt it shouldn't effect the paint.
Reply:check out POR-15  POR stands for paint over rust most of the car restoration guys use it for their frames. you dont have to worry about it rusting again.
Reply:If you had enough rust to chip off with a slag hammer are you sure that you have enough metal left?
Reply:the metal in all areas is still full width, the rust didnt eat into the metal, it was sitting on the bottom cap, kind of hard to explain.My plan was to wash the inside with water, then simple green.  sandblasting isnt neccesary, everything besides the bottom of the tank look A OK.  I might take a scotch brite wheel and clean up the surface of the bottom cap, but other than that it looks ok too.i like the idea of pouring paint in and rolling it around on the floor.ive used por 15 stuff before too, pretty good stuff.thanks for the input
Reply:I'm surprised no one has mentioned it so far - buy a new tank that has been properly built and static pressure tested.  Do you know how dangerous your rebuild sounds?  I don;t care if you're the best welder on the forum, this sounds like a very bad idea.
Reply:Originally Posted by TubularFabI'm surprised no one has mentioned it so far - buy a new tank that has been properly built and static pressure tested.  Do you know how dangerous your rebuild sounds?  I don;t care if you're the best welder on the forum, this sounds like a very bad idea.
Reply:Somebody had to weld that tank before it left the factory. Surely you can weld as good as the factory worker.
Reply:Originally Posted by 808APPSomebody had to weld that tank before it left the factory. Surely you can weld as good as the factory worker.
Reply:i plan to have it pressure tested, thanks for the safety tip tho
Reply:ya know, now that i think about it, im going camping here in a couple weeks, a big firepit would be pretty sweet to bring alongplus i just emailed a guy about a new tank on craigslist, 60 gal vertical for $65
Reply:well just for future refrence painting the inside of that tank would just be a waste of paint,go to your local paint store and get some stuff called rust cure
Reply:I bought an old air tank at a yard sale intending to make a grill.  When I cut it open, i found that the bottom inside was coated with some sort of rubber which, I assume, the manufacturer used to prevent rust.  Sounded like a fine idea for an air tank but i was not keen on the idea of rubber flavored steak so I trashed the tank.
Reply:808app that factory worker might be a robot, welding new steel. unfair matchup.
Reply:i weld pressure vessels all day long ant no thing just weld it like you mean itChuckASME Pressure Vessel welder
Reply:i agree with you chopper, im not a pressure vessel guy, but i have structural d1.5 certs, which arent easy tests, and am confident in my abilities to put something together, and make it stick.im not really sure what im gonna do with the thing yet...
Reply:This was the post I was referring to.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:If you HAVE TO weld an air tank - "TEST IT"Fill the tank with water, then apply the pressure.water don't compress, if the tank cant hold the pressure it will leak at the failure point.
Reply:Originally Posted by Magnetic MechanicIf you HAVE TO weld an air tank - "TEST IT"Fill the tank with water, then apply the pressure.water don't compress, if the tank cant hold the pressure it will leak at the failure point.
Reply:what's a creap?
Reply:Originally Posted by Magnetic Mechanicwhat's a creap?
Reply:correct slowly add pressure untll you pass the capacity you need or the tank leaks
Reply:then let it sit and watch the gauge to bleed off some  over a day or two ??
Reply:not a bad idea if you got the timewell i have wet checked heads and water seals fine ,,put a solvent in there and leaks ,,,but for the cost of the solvent i can buy a new tank