Silver Solderin

I need some help please, I am in the process of building a boiler for my Wilesco Traction engine rebuild and want to silver solder this together, the originals are all soft soldered but I am wary of this particularly when I start adding in various blanks for mounting parts that if the boiler is soft soldered then it may well fail on some of the joints.

I have soft soldered and whitemetal soldered for the last 35 years so not afraid to try something new, my question is what type of torch do i need and where can these be obtained from, what do most use for gas bottles ...

I have looked up a number of you tube tutorials and will pick up silver solder Easy Flo No2 and flux from EKP.

John,

you could do no worse than chat to the guys at Cupalloys....they really are the guys in the know....

personally I use a butane torch for small stuff, but then use a propane torch where more heat is required...on bigger stuff.

Hi John,

Topic has been covered in lots of threads. See here

**LINK**

Ignore first result as that is this thread.

Gary

Hi John

go to www.cupalloys.co.uk/best_practice/

Any further help? Call us or talk to us at Alexander Palace in January

Regards

Keith

Should have read no better.... I think..whatever.....I best stop digging....

...errm basically, they are the boys!!

Edited By John Rudd on 29/12/2013 17:16:36

Hello Mike

I live in South Devon in Paignton, anyone out there who can help?

John

Very helpfull tread will follow up the links and have bookmarked these to comeback to, once again thanks for the advice.

What percentage silver solder is required for model steam boilers and pipe work ? My local hardware store has a range of silver solders : 2%, 5% and 15%. Are these adequate ?

Brian the low % solders are typically used for refrigeration and air conditioning, they are a copper phosphorous alloy and not what you want for a boiler. You want a 55% designated ISO 17672 Ag 155. Not sure what makes are available in Australia but something like Harris Safty-silv55 would do.

HI Brian. As usual Jason gives very good advice. The range of alloys held by your hardware shop are the silver copper phosphorous alloys designed for the fluxless brazing of copper to copper in industries such as refrigeration or air conditioning. However, before you get excited by the fact that you are wanting to join copper to copper, these alloys suffer rapid corrosion in hot sulphur-containing atmospheres, eg a coal fired boiler! They should not be used by Model Engineers for their boilers.if coal fired. The Ag155 alloy with 55% silver (or as we call it 455) is the lowest melting point alloy commercially available in the EU. If you are in Australia you should still be able to buy the cadmium bearing alloys of which the 42% silver alloy has a slightly lower melting point still. As posted earlier on this thread, if you require any further advice or assistance please do not hesitate to contact us.

[email protected]

Edited By shaun meakin 1 on 08/05/2014 09:27:16

I live in Cairns, Australia. There is 45% silver solder available on ebay but it is expensive stuff ! I will look around for the cheapest supplier in either the UK or the US.

John, from the wording of your initial question etc. I take it that you are building a new boiler, and? making it from copper. Yes as Brian says It's expensive, but you don't need too much, and it's good to do the job correctly. Take note of the advise, if any metal to be silver soldered has tin lead solder on it DON"T, not at least until ALL the old solder is removed. Other wise you may as well use low temp solder, because the joint will be stronger than the contaminated one. Ian S C

John, many thanks for the info. In truth the same apples, as the silver copper phos range of alloys will also join brass but with flux. However, again the joint will suffer rapid corrosion in a hot sulphur atmosphere so they should not be used in a coal fired boiler.

Brian, you can get a 45% cadmium free alloy in the UK (our 445) but I don't think you will be able to source cadmium bearing alloys in the UK. This is because the demand now is so low (ie only to countries outside the EU) that it is not stocked, not to mention that the EU manufacturers cannot by law supply UK customers with these alloys, regardless of where they are ultimately sold on to.

Shaun.

I have bitten the bullet and spent money on a torch and silver solder from Cup Alloys (great firm only to ready to help) haven't got round to trying silver soldering yet but will make a couple of small parts that need silver soldering so will see how it goes.

Have now silver soldered my first couple of parts as a trial some spare copper plumbing parts, next question I have a 50g packet of Citric Acid Monohydrate powder, I need to make up a solution to pickle the parts soldered - how much do you mix up and what proportion.

I've often seen a few tablespoons i in a gallon recommended, which seems very weak to me, given how much is in the average kettle descaler packet, but apparently this works well and if you make it stronger it can go a bit funny..

Neil

Ok what is a few is that ?

John, stick about half your 50g packet in a plastic bucket. After you'v used it, you can store it, put it in bottles, it will last for ages, might get mouldy on top, just scrape it off, and as it evaporates, just add water. Ian S C

If the boiler is being re-built from one which has been soft soldered, you may have a serious problem. When heated above its (low) melting point the lead or tin (etc) from the slightest trace of soft solder left in place is liable to soak into the surrounding brass (or copper) giving a very odd alloy which will not take the hard solder.

Secondly, battery acid (dilute sulphuric) is perfectly good to remove hard-solder flux residues. Half an hour should be enough. Use the acid as it comes (new and not out of a battery) or let it down 50/50. And as it is dilute acid, do not panic about adding water to acid or vice versa. But do resist the temptation to plunge the still-hot job into the acid - the splashes will make holes in your jeans, your vest, and anything else around. Was away any splashes with a solution of washing soda (Sodium Carbonate) or baking soda (Sodium bicarbonate).

And do practice hard soldering first, on some off-cuts of the material you are using. Get both sides to the same 'just red in the dark' temperature, and remember that the solder will flow into the hottest part of the joint.

Hope this helps.

Cheers, Tim

John, we sell 100gr packets of cleaning salts which make approx 1 gallon. Therefore (with my shoes and socks off) I calculate 50gr to make up about 4 pints!!!

Also thanks for the kind words.

Shaun.