Can I weld Malleable Iron Fittings to Mild Steel Plate

[awemawson]

As per the title, can I weld malleable iron pipe fittings to mild steel plate? (I want to form a flange on an exhaust system that is made from 2 1/2" BSP pipe and fittings)

 

[Brad93]

Yeah

 

[WorkshopChris]

I have seen a few cracks over the years, so I presume the fittings may well vary considerably between manufacturers.

 

[awemawson]

Extensive Googling tells me that malleable fittings are made by heat treating ordinary cast iron (which I sort of knew) but welding heat then cooling can undo this heat treatment leaving you with ordinary cast iron, with it's potential brittle welds.

I think I've pretty well decided to bore and thread the mild steel flanges on the lathe, then bronze weld / braze them as well but would welcome comments.

 

[frank horton]

then what are weldable fittings made from....
honestly didn't know about the above, treated c/iron.......
must have welded hundreds over the years....

 

[Turbo]

It can be hit & miss welding iron fittings, some weld nicely, some are just horrible, probably depends on quality. Either way your best method would be stick or tig using a dissimilar metals filler rod.

 

[Bill Edwards]

I only tried it once, it was cheaper than a weld on fitting and I figured it would be fine...

After much struggling it ended up with braze being run round it to fill in all the porosity, nasty stuff it was and never again would I choose to weld it.

 

[8ob]

Why bother welding malleable when you can use steel? Can you not weld a steel socket or nipple to the plate and then screw whatever malleable fittings you have to that?

Bob

 

[awemawson]

As it happens Bob I've just ordered up a 'barrel nipple', and 'short socket' in 2 1/2" BSP so that I can screw and weld the barrel nipple into the the mild steel plate and work onward threaded from the socket !

Great minds etc !