Welding crack in cast iron central heating boiler

If it is a small crack, how about trying it with Holt's RadWeld?

Nick

Gosh, I remember that stuff. Had a car in the 70s which used that nearly as fast as petrol. Might work for a temporary repair though.

David

David Littlewood responded to

Yes, I think the plot used to be an initial tin of RadWeld, followed by one tin of RadFlush. This was followed by two tins of RadWeld, and two tins of RadFlush. Ad infinitum.

Seriously though Dave, I hope you get your crack sorted out OK..

A cheaper solution would be noodle's water.

Nick

Got any oxygen at hand? I could have a go at silver soldering (or even soft soldering), and I pass by Stroud on the M4 from time to time. Thing is, I use an oxygen generator at home, which is plumbed-in and isn't exactly portable.

'Nother question, mostly for you - I have heard that drag racers use Inconel outlet valves in their engines, and that the top drag people only use them once or twice before replacing them. Some of the used valves are reconditioned and sold, some are sold as-is, and I guess if eg one of a set has broke the rest are junked.

Anyway, my question is, do you know of a cheapish source of such used valves? Will not have to be used in engines, and do not have to be in sets, so unless they are bent or otherwise sort-of-destroyed anything that survived would be of use.

(I want to use them to make turbine wheels with integral shafts for rocket engines - the valve diameter doesn't matter, as the common sizes are all too big anyway, and neither does the shaft diameter or length, again they are more than big enough anyway)

Hmmm, that's a thought. Not sure what it would do to the pump and valves in the system though. I'm also not keen on the idea of me trying to bleed radiators and Radweld trying to seal the opening at the same time.

-- Dave Baker Puma Race Engines

Ummm, so do I if I'm a very long way from home :)

Thing is, I

Where abouts is home?

I don't personally know anyone who uses inconel valves in anything. Drag racing at that level is a bit outside my line of country. Nimonic is used in a few standard truck diesel engines though. Would 21/4N austenitic steel exhaust valve material not cope with the temperatures you encounter?

-- Dave Baker Puma Race Engines

What boiler is it? I had a Baxi cast iron boiler that was leaking and when I pulled it out it was in two halves bolted together with a gasket in between. I put some silicon sealer on it and bolted it back together as a temporary repair while I got the new gasket and it lasted ten years before I had to remove it again and fit the gasket.

I would try it with all the radiators disconnected. Me to wouldn't like radweld in the valves.

Decades ago, I also had a crack in the boiler and intended to weld it (with nickel). But I was told that it won't work. You only will get a new crack, except you heat up the boiler (oh, that's what he was made for) quite (say

Nick

I've had good results welding cast with what I believe are called "weldall" stick welding rods. Try asking at your local welding supply outlet. They used to be about £1 each 15 years back :) I understand they contain a large amount of stainless steel? Just grind a nice V in the crack and weld away.

Good luck, Pete.