Boiler stay Material

On the 5" Loco boiler the drawing it states GM or Monel metal for the boiler stays threaded 4BA one set and 1/4" for other.

Is it OK to use monel rivets threaded on one end?

I would say yes, many boilers are constructed this way, and the rivets if not threaded, peened over prior to the silver soldering.

Good evening Bob,

What ever you do, do not use monel for stays; you didn't indicate which locomotive boiler you were involved in, but I'll take a guess it is one of the Martin Evans designs; he did on a number of designs specify monel for stays and from my experience of using monel as a stay material it can present considerable problems should you need to reheat the boiler, the monel has by then taken on an almost impenetrable black patina that is most difficult to remove. My choice of material would be to use copper rivets for the side stays with heads on the inside of the firebox and drawn phosphor bronze for all other stays, e.g. roof and longitudinal stays, all being silver brazed after fitting.

Regards,

Bob Youldon

Bob

5" Nigel Gresley 2-8-0 which is as you say is a Martin Evans design, problem is there is no mention of copper stays on the drawings. Do not have a problem using copper but as it was not specified hence the question.

The material cost to build the boiler is quite high and with all that copper I did not want any errors.

Bob

PS.

Anyone got a piece of 6" 10swg copper tube 27" long they want to sell?

hi bob,

bob youldon's advice is very sound. you cannot silver solder monel metal - there was a letter in ME from johnson matthey about this some years ago after Reeves had bought a load of it as people were asking for it as martin evans specified it.

i dont like martin evans' large stay pitch with large diameter stays, and i also think that gunmetal is totally unsuitable for boiler stays (even if you can get it these days in the right size). hard drawn phos bronze rod or copper rivets.

cheers,

julian

Julian,

Are you saying 1/8" stays are large? The firebox sides ( 8" x 6" ish) have 48 stays 4ba and 9 1/4" stays across the top.

hi bob...

i dont like the large diameter stays of the martin evans designs or their large pitch - 'pitch' meaning distance between the stays. there is nothing wrong with 1/8" dia stays on a 5"g loco but the pitch as used by don young ought to be adopted for same IMHO, and is incidentally what the professional boiler makers do as well.

cheers,

julian

So what is considered a reasonable pitch?