Rothenberger Rolot brazing rods

I have been offered some Rothenberger Rolot S2 brazing rods but I am not sure of any application which may be relevant to me. The composition of the rods is Copper 93% Phosphorus 6% and 1% silver. In industrial use they are apparently used to braze copper plumbing tubing for gas, water etc. The stuff has a working temperature of 710 deg.C and a melting range of 650 - 810 deg.C. Does it have a use in model engineering?

Could it be used to braze boilers? I seem to remember reading somewhere that phosphorus bearing fillers are not suitable for use in coal fired boilers because of a reaction with sulphur which weakens joints. What about using it in gas /spirit fired boilers?

Mick

I also saw these rods in a well known DIY store and had the same thoughts. I have however just bought some old volumes of ME ,early 70's and there was a article about these in it. I have to date only scanned through the article but the jist appeared to be if it was a boiler that was regularly used there was a crystalline formation around the soldered joint which in turn weakened them.

May be worth having a look through the archive, I'll have another look and when I find it I'll let you now the issue No.

Bob

Two things on the Rothenberger site that would put me off using it for boiler work

Not to be used on materials containing sulphur so possible issues using coal

Heat resistant upto 200deg C so bit iffy in a firebox.

I am not great on the computer and whether it was me or my machine I don't know but when I Googled this stuff the Rothenberger site didn't come up !. Thanks anyway Jason. That figure of 200 deg C seems a bit strange given the MP of the stuff. Thanks for looking Bob.

Mick

I got the wrong year but the article is in Issue No 3626 ,Vol 146 1-14th February 1980

Thanks Bob....I might even have that volume and will check tomorrow.

Mick

i would endorse jason and bob's advice. under no circumstances must phosphorous containing (cheap) brazing rod be used on locomotive boilers. keith wilson got into a lot of trouble over using this cheap alternative on his locos plus suggesting the use of same. one ME contributor sent samples off to a laboratory and the results were pretty damning. buy the proper stuff from the ME suppliers such as Cupalloys and keep the receipts in case your boiler inspector wants to double check what you've used.

cheers,

julian

Under no circumstances should an alloy containing phosphorus eg Rolot S2, S5, Silbralloy, Silfos be used to braze copper that may come in contact with hot sulphur bearing atmospheres. The sulphur will go through the joint like a hot knife through butter!

Equally these alloys should not be used to braze copper to steel or any non-ferrous alloy containing nickel.

The phosphorus forms a very brittle intermetallic compound with iron and nickel. For more information on this point investigate the disaster associated with the submarine USS Thresher.

Keith

PS in gas fired boilers - no problem. All copper/copper joints in your central heating boiler are made with these alloys.

Edited By CuP Alloys 1 on 12/02/2014 23:59:23

There is no mention of phosphorous in the wiki entry for this boat

uss thresher

Were you there?

I speak from experience concerning the Derbyshire

I was on a sister ship, coming in behind them in the aftermath of the typhoon

Or are you a conspiracy dude...?

Edited By Ady1 on 13/02/2014 00:43:25

Ah Adi1, they must have known the specs on the brazing though, but I see they did not quote the grade in the Wiki report. Ian S C

Just noticed that Screwfix have a Rothenberger Soldering and Brazing kit with a Super Fire 2 torch on special offer at £99-99. If is worth buying?