Welding Cast Iron?

[Alky]

I'm also working on building a bigger air compressor (about 25 cfm @ 90 psi) for low bucks: watching ebay and craigslist for compressor pumps and motors, and I'll use an old galvanized steel water pump tank for the air tank.
Those old-style water tanks are massively heavy ... definitely strong enough to handle 150 psi.

I built a compressor tank out of an old tank of unknown origin, it was a 600L tank, and it was quite massive. When filling it with air, one of the welds must have failed. A fraction of the tank remained in the garage, the rest made a hole in the wall and disappeard. I was standing almost right beside it when it blew. Can't remember a thing. The blast knocked me out.

Make sure you check that the tank is pressure rated, and DON'T EXCEED.

Hint: If the tank fails, go look for it in your neigbours backyard.

[Charlie C]

MontanaMan befor using the tank for air pressure hydrotest the tank to maybe 150 to 200% of what you will be using for working pressure. Using a water tank is real riskey business. You might not be as lucky as Alky. If I am telling you something that you already are aware of please excuse me.

Where I worked one time we had a pressure tank, that had an acid in it, rupture and killed four men.

[jfsmith]

I would just find a place that rebuilds commercial shop compressor and buy a tank, less hassle, because of liability issues they won't sell you a bad one.

Jerry

[MontanaMan]

Thanks for the input ... I think you guys are right about the water tanks. I've been doing more research, and there have been a lot of accidents with "unknown" tanks. First, I was thinking of using a Wel-Xtrol 60-gallon water tank, which is rated at 125 psi, then I thought an older, thicker galvanized tank would be better. But ... 125 psi is shaving it too close, and an old galvanized tank is too much of an unknown. It's probably safe, but why risk it? My daughter might be walking past this thing when she gets older.

A better option, I think, is to use empty Freon tanks. They are guaranteed to have no water in them, and they have only been used once. And best of all, they are certified rated at 250 psi -- the same as air compressor tanks. Only downside is that they are small ... I think the biggest one I can find locally is an industrial sized one which is about 25-30 gallons. You can usually get them free from HVAC service contractors.

Also ... a key component of tank safety is draining the tanks religiously. Even on my little nail-gun dual-tank compressor, I installed 2 ball valves to make it easy to drain the tanks, and I drained them after each use. It's suprising how much water comes out on a humid day.

[SkidSteerSteve]

tank drain

Here's a little trick I found to regular tank draining....

I don't know who decided that those little wing-nuttish looking drain valve are adaquate, but I shure don't like them. I remove them and replace them with a spring loaded drain valve designed for air brake storage tanks. Then you can leave the cord hanging to the side of the tank and just give it a yank as you pass by. After all, that's exactly what those little $5 parts are intended to be used for. I don't consider myself lazy, but any convienece I can work into my day, I'm all for it.

Also, I'll throw this out there and see what happens...I know a lot of people (maily small shops/hobby garages that plumb their air systems with PVC pipe....DON"T!!! while pvc has a pressure rating suitable for most air systems, they are designed for fluids, not gases. I know people that have gotten many year's service out of them, but I wouldn't risk it. If a plastic pipe ruptures, there will be hundreds of little pvc arrowheads flying about the shop. Not to mention the fact that they can get brittle in cold weather (oh and decompressing gas has a tendency to chill them down as well)


Just an FYI I thought should be out there.
-SSS

[aametalmaster]

Ring is in the mail.

MM your ring is in the mail. Glad to have helped...Bob

[MontanaMan]

Well ... that's the prettiest looking ring I've seen in a long time ... :-)

Thanks Bob, and let me know if there is ever anything I can do for you.

[weldingcowboy64]

Cast Iron.

The shape of the cast iron drill press part looks like it could be fabricated out of some pipe and other metal pretty easy or have a local machine shop make one. Or like some of the others have said, Hi nickle rod or wire and pre-heat and post heat , cool very slowly. Good luck

[Darmik]

Cast welding

You must pre heat the casting 350 to 500 deg F
with out delay the welding must take place very quickly after pre heat
You must also Lightly peen the weld after each bead and alternate the welding on both sides. you must grind out both sides making a 60 to 90 deg bevel
you can use 7018 because your break is not moer than 60% of the casting
Now here is the fun part what cast rod are you going to use?????
there is Aws category RCI , ECI , EST AND ENI cast rods
good luck

Darmik

[squig]

just my 2 cents

There is a lot of good quality cast rods on the market I would vee out one side and bolt it back up .Then i would postion tack on the press remove it to the bench weld it up ,all this time the peice is pre-heated to about 100 degees ,or as hot as comfortable to handle >check it a couple of times for fit up,Vee the other side and weld up The whole time gently peening let it cool slowly and youll be good to go till your new peice comes in!

[m.k.swelding]

cool slow

alwase preheat and let it cool slowle. keep the torch on it and let it cool slowle

[thunder71]

welding cast iron

it can be done & i do it all the time when i need to with good results...i take nickle base stainless steel stick rods,beat the flux off,sand it down good & clean...clean the cast iron up & V it out real good with a bevel...preheat with the oxy/ace torch & tig it back just like you would Stainless steel...it can be done

[kmomaha]

Montana Man;

It may be cast steel. Not a whole lot of stuff is made out of cast iron anymore. Cast steel will weld much bettter. If it's Chinese... who knows?

I take it you are from Montana or in Montana. I was born in Sidney, Mt.

Good luck. Sounds like you've got some guys to help out.

[FusionKing]

Montana Man;

It may be cast steel. Not a whole lot of stuff is made out of cast iron anymore. Cast steel will weld much bettter. If it's Chinese... who knows?

I take it you are from Montana or in Montana. I was born in Sidney, Mt.

Good luck. Sounds like you've got some guys to help out.

This is a 2 1/2 year old thread. Even tho much of the info is still relevant many of the people on it have not been back on here forever. They are not gonna answer you back.
MKSWelding has dug up about of a dozen or so of these now