TIG welding cast iron.....HELP!

[Mid Wales welder]

I've got this job at work now which is going to drive me crazy! It's a load of old cast iron guttering. Mainly cracked at the ends as you can see, 3mm thick. The down pipes are 5mm thick which I will have to replace the ends with mild steel tube. There is also a piece cracked in half.
Anyway, they have all been sandblasted, I've drilled a hole at the end of all the cracks to stop them getting worse & I've cleaned them all back to shiny metal. I have no idea how old they are, guessing over 100years. They are very britle!!
I was going to stick weld them with 2.5mm castoline rods, but they are quite old rods & they just seemed to bubble up. So I nocked all the flux off & cleaned with a grinder & decided to tig weld useing the cleaned rods as filler. I didn't pre heat as they are quite large peices so set about 45amps & just did a 10mm long weld, very little heat input to see what would happen & sure enough as soon as I stopped I could hear it poping & cracking.
I have no idea how to combat this as I tried it in a few places & the same thing kept happening!
Any advice people can give would be very much apriciated! Thanks in advance!

Dave

 

[Mid Wales welder]

This is the down pipe which needs a new tube on the end & there are 4 of them

 

[Mid Wales welder]

All these to do.....aaaarrrggghh!!

 

[Lawnmowerboy]

there will be tons of dirt coming out the crack when you arc up i would have thought. I would preheat to about 150 and drill the end of the crack to about 3mm and weld.

 

[Master-of-none]

Have you considered brazing? A quick google and This thread has a nice example.

 

[Mid Wales welder]

there will be tons of dirt coming out the crack when you arc up i would have thought. I would preheat to about 150 and drill the end of the crack to about 3mm and weld.

Yep, bubleing like hell! I put a 3.5mm hole at the end of all the cracks. Would just preheat around the crack? I thought the whole piece needed to be pre heated? Only got oxy propane & by the time I get from one end to the other the place I started would have cooled lol. We have a powder coating oven, do you think that would work?

 

[Mid Wales welder]

Have you considered brazing? A quick google and This thread has a nice example.

I've never done any brazing on big parts like this, I still have the problem of pre heating & we don't have a digital thermometer. Would brazing work on joining mild steel to cast iron?
I can see this job driving me crazy! Doesn't help that we are really busy & the boss wants it done quick as

 

[Shedendman]

Sorry,but i cant see why anyone would want to keep cast iron guttering etc,nevermind repair it,is it for a listed building?

 

[Mid Wales welder]

Sorry,but i cant see why anyone would want to keep cast iron guttering etc,nevermind repair it,is it for a listed building?

I know what u mean! Yes it's for a listed building, I think the guy has spent a lot of money on it, he had to get some matching stuff from eBay & he's spent over £2000 just getting it all painted! He's crazy if you ask me lol.
I'm sure we could make new stuff for less. It's powder coated white & it looks no different to UPC stuff when it's up there, but u know what they're like with listed buildings!

 

[Robotstar5]

Has he looked at Saint-Gobain for new stuff, they still make cast iron guttering etc.

 

[Shox Dr]

I think thoserods are far too heavy even using with tig. Ive been successful with 316 1.2mm.

Lots of little tacks. And slowly goes it. Just hop from one to the next it will soon be done

 

[Mid Wales welder]

Has he looked at Saint-Gobain for new stuff, they still make cast iron guttering etc.

Excellent, If it all goes wrong I'll let him know about that. I bet it's quite expensive, but then I don't think that will matter.
Thanks for that!!

 

[Mid Wales welder]

I think thoserods are far too heavy even using with tig. Ive been successful with 316 1.2mm.

Lots of little tacks. And slowly goes it. Just hop from one to the next it will soon be done

Yes think they are too thick, my thinking was as soon as I get a puddle, just put one dip of that rod & it would cool the puddle & then stop.
I did try some 1.6mm 316ss thinking as its crack resistant it might work, but it just cracked the cast next to the weld lol
I also tried some .8 mild steel mig wire spun in a drill to make it 1.6mm again thinking the extra silicon might clean the pool (worth a try lol) & it ran really nice but again just cracked straight away!
I'll just have to try a small spot tack in lots of places & as u say go it slow untill it's done.

 

[piman]

Hello M W W,

" Would brazing work on joining mild steel to cast iron? "

Yes it will, quite effectively.

Alec

 

[Mid Wales welder]

Hello M W W,

" Would brazing work on joining mild steel to cast iron? "

Yes it will, quite effectively.

Alec

That's good to know, many thanks!

 

[TechnicAl]

TIG is too hot

Stick is the best method providing you use the specialist rods

 

[brokenbiker]

either stick or brazing would be my choice. preferably brazing

 

[aametalmaster]

A mig welder loaded with cast iron wire and argon gas would make short work of those parts. But i don't think that the wire is in your part of the world. Bob

 

[Wendelspanswick]

I have repaired ornamental cast bits with normal mig, small weld, let it cool and then another small weld, the trick is not to involve too much heat as it will crack when it cools.

 

[Mid Wales welder]

TechnicAL: I used TIG over stick purely because our cast rods are quite old & they seemed to bubble quite a lot when I lit up. So I knocked the flux off the rods & used TIG. I would have thought the TIG would be cooler also as I was only running 40amps, or is this not the case?
aametalmaster: I didn't realise they did cast iron mig wire, I shall have a look thanks!

I will see if we can get some brazing stuff tomorrow, but as the boss needs this done fairly quickly it may be the case that I'll have to make do. I shall try all the methods suggested that I can tomorrow & post of my success or demise after lol
Many thanks for all the tips everyone, very much apriciated!!!