repairing a small boiler fracture

JasonRinaldi

I came across a small domestic steam system that has a small fracture below the water line near the wet return. Could this be repaired by welding? There are no other fractures on the boiler other than this one. It may have been caused by freezing when the boiler was inadequately winterized.

kcopp

You cant weld cast iron... braze maybe. However.... by doing so you take all responsibility/liability if there ever was a problem. So no you need to replace it.

MichaelK

You can weld cast iron, but you need cast iron rod for oxy welding or cast iron welding rod for a buzz box. Then there is the pre heat and post heat and hope it doesn't pop somewhere else.

Also, welding on a pressure vessel involves special stamps and you will own that baby as kcopp said.

Probably not the best route to take. Could cause issues down the road.

Can the section be replaced? Or is it pressed or all one unit?

Sailah

I've successfully welded cast iron a few times with TIG welding but honestly I'm going to call it more TIG brazing as I don't think the base metal actually melts but I could be wrong.

I preheated the part to about 500F, welding using AC and silicone bronze filler rod.

It was for a exhaust elbow on a friends marine diesel engine and worked great.

Not sure it's worth doing for something that might cause problems as it's prone to cracking if you don't preheat or cool slowly. I put mine back in the hot oven and slowly ramped the temp down over a few hours.