Using Blind Rivets on a copper boiler

[henry]

Hello,

I am building a 5" gauge copper boiler where the flanged joints are riveted together and made steam tight using silver solder. I had originally planned to use copper rivets and to use a dolly to form them. 

However, I was wondering if I could save myself a lot of time by instead using blind rivets? These would be installed using a hand riveting gun and copper body, bronze mandrel rivets. Is this safe to do? Will these rivets be as strong as traditional rivets?

Many thanks,

[uuu]

In modern boiler consruction, it's the solder joint that has all the strength. Rivets are just used to maintain alignment during soldering, and are not fully tightened, to leave a capillary gap. In days of yore, joints were riveted to provide the structural strength, and soft-solder caulked.

Blind rivets sound a bit weird in this context. Bronze and copper sound OK. This could either develop into a really interesting thread, or you're about to be cut to ribbons, by the experts (of which I'm not).

Wilf

[jackrae]

Are you building in accordance with the design drawings and the approval of your club's boiler inspector ?

[isc]

I'v never built a boiler, but I'v been led to believe that the rivets, or screws are only there to hold things in place until the silver soldering is done. If you use the Pop Rivets that you mentioned, it could be done, but you would not fully close them, so the tails would not break off.isc

[jma1009]

hi henry,
you should ideally use as few rivets as possibly in copper silver soldered boilers. i used just 4 or 6 in my last 5"g boiler. they are a pain as easily missed when silver soldering yet must also be silver soldered and not be closed up tight otherwise no penetration of silver solder round them. also difficult to get them to attract the heat unless left long but squashed down a bit. the more holes you have the more potential source of leakage.
if you close up the gap between the joints with a rivet then you are probably preventing the silver solder flowing through the joint (needs 2 to 4 thou max gap) plus probably also preventing the joint being properly cleaned and fluxed before silver soldering. there are ways round closing up the gap, but the other problems still remain.
cheers,
julian

[maninshed]

I'm building a small 7 1/4" gauge boiler, as quoted earlier I have used minimal rivets of 3/32 dia, just to hold things together. I think the rivet things together came from LBSC's days when they used different solder and paraffin lamps for heat.

Martyn.

[suctionhose]

Just completed a largish one. Weight 30kgs. Used silicon bronze screws from a boat building supplier.
The screws are 98% copper with 2% silicon. They ss well and have the benefit of being able to dismantle and assemble the boiler multiple times during construction.
Brass screws are unsuitable due to dezincification.
Ross

[davebreeze]

Feb 18, 2014 22:44:15 GMT suctionhose said:

Just completed a largish one. Weight 30kgs. Used silicon bronze screws from a boat building supplier.
The screws are 98% copper with 2% silicon. They ss well and have the benefit of being able to dismantle and assemble the boiler multiple times during construction.
Brass screws are unsuitable due to dezincification.
Ross

There was a good series a while ago in Model Engineer by Alan Crossfield where he built a boiler for a GWR loco. He used bronze screws to hold it together for soldering and to adjust the gaps.

[ejparrott]

That's my normal method.