How do you solder brass cones/nipples onto copper pipe

Hi All

iv been trying to silver solder cones onto a 5/32" copper pipe with zero success, i need to attach cones ect onto injector pipes, and boiler clacks ,all im doing at present is melting the brass cone, and softening copper pipe,everything getting far to hot, soft soldering an option? Ie comsol?

Would appreciate help on this

cheers

Mark

I am no expert on these things but I am currently doing the plumbing on the loco and tender that I am building. In "hot" areas in the vicinity of the boiler and smokebox I prefer to silver solder the joint although I am pretty sure that HMP soft solder eg Comsol would do the job most of the time. When silver soldering this type of joint I have also melted the brass nipple due to careless overheating. The way to avoid this is to heat the copper pipe only and let the heat travel down to the joint to melt the flux and then a dab of fine wire silver solder should do the trick. At the last ME exhibition I went to I was overcome with profligacy and lashed out about fifteen quid on a small syringe of silver solder paste. It brought me out in a cold sweat and a touch of the shakes at the time of purchase but it must rank as one of my best buys of all time. Only a tiny amount is needed to make the sort of joint we are talking about and it is an absolute doddle to use. In "cold" areas such as the tender water connections then ordinary soft solder I find to be quite adequate.

A word of warning about silver solder paste.....there are some offered for sale on the net that only contain a very small proportion of silver and really fall into the HMP solder category. I bought mine from CuP Alloys.

Mick

Cleanliness is an essential factor for success. As is a good fit: not tight, but just a suspicion of looseness - but not a rattling fit either. There should be just enough clearance to allow the solder to be drawn into the job by capillary action, but no more.

Flux the joint well, then (as mick H suggests) avoid heating the nipple directly. As you have discovered, the danger with direct heat is that the nipple melts. Apply enough heat to bring the job to temperature quickly.

I agree that solder paste is a good idea. A ring of fine silver solder wire around the top of the joint is a good idea instead. As noted, quality of solder is important.

Hello Mark,

I would never recommend the use of soft or Comsol type solders for this application. Silver brazing of a cone onto the end of a small diameter copper tube is a reasonably simple exercise given a bit of practice; what you need is to arm yourself with a length of 1/32" diameter Easyflo 2 or the equivalent as the filler wire, next a fairly small propane burner is required, a couple of heat resistant bricks including a few odd broken pieces as props to hold the job in position and to reflect the heat onto the job; now the trick is to gather up a few odd ends of the copper tube and try warming them up to a dull red, you'll get to know how much heat to apply, how close to hold the lamp etc, in other words have a bit of practice before diving in and doing the actual job. To make applying the silver solder wire easier get yourself about a 4" length of fairly small diameter brass tube and push the wire down the tube leaving about 1/2" protruding, its gives you great control when you are about apply the solder to the job. When you are reasonably confident of soldering the nipple onto the tube, clean everything well, flux up the job and make a start warming the area very carefully until the flux has melted and can be seen as a clear molten fluid, now is the time to just touch the appropriate area of the job with the solder wire, no more than 1/4" of wire will be required for a sound job; let the job cool to black and pop it into a pot of clean water leave it for a while to soften the flux residue, following that you can generally just wipe the job and it'll clean off any remaining flux easily. Have a couple of practice goes, sadly it's only practice. Best of luck.

Regards,

Bob Youldon

Hi All

Many thanks guys for all your advice, i shall be taking it all on board.

Just a couple more questions! You mention using asmall burner to apply heat, iv only got one of those handheld plumbers propane blowtorches, from bnq! Im guessing thats to big even for this job, would one of those jewellery blowtorches be any good? Or can you recommend a type and brand

Mick, this silver solder paste, would it be 455 by CuP alloys?

Again thanks guys for your expert advice

Mark

Yes, the stuff I am using is 455 paste in a 10gram syringe. (I have ordered by post from CuP and I believe that their prices include postage).

I presume that your blowlamp has got quite a big flame area but it is OK to use provided you turn it down a bit and you are careful where you direct the flame. My "plumbing" is usually on 3/32" and 1/8" copper pipe so I find a smaller blowtorch adequate and I also make use of kiln bricks to set the work up on and reflect heat.

Mick

Just remember to put the nuts on before soldering the last nipple !

I've got a cook's blowtorch that cost about £8 in Aldis. Ideal for this sort of task. Also very handy for lighting larger torches as it has a piezo igniter built in.

Neil

Hi Mark. As usual sound advice here. For info if you find your blowtorch too big we have just launched the new Hanydyjet torch which is the 'baby' of our torch kits. **LINK**Sorry Neil but i don't think the cook's torch will generate enough heat here for silver solder. Always try to heat the larger component first, letting the smaller piece get it's heat from the larger, playing the flame around so as to bring the whole piece up to temperature at the same time. As stated, ensure you are using the correct silver solder. For small pieces such as this use the lowest melting alloy containing 55% silver (our 455) unless of course you still have some of the cadmium bearing alloy left. As well as the paste mentioned by Mick 455 is available in fine wire 0.5mm dia which again will help you here. I hope that helps Mark.
Shaun.

you require a good blowtorch,a well known brand ,ie primus sievert, I bought a similar outfit made by Calor and that has lasted fifty years. and well worth the price .Though when I started work all we had was a plumbers paraffin blowlamp for silver soldering. this week I have been experimenting with the hot tube ignition of a Gardner gas engine trying to improve the burner which heats the hot stainless tube,the problem is a gas engine was not meant to run on a windy steam rally field ,I am currently using a small sievert burner but wanted something a bit larger and was bit reluctant to buy another quality burner which may not work ,a friend offered me a couple of new burners from a cheap source and to be frank they were rubbish, one burnt with a yellow flame ,lack of air,and the other produced a fluffy blue flame which kept going out. I have set up on an engine which works and was trying to set up a second engine but the sievert burner and more important the jet is obsolete ,and a similar new sievert I bought was not hot enough,the jet had a different number. So dont go buying cheap blowtorches,my friend now uses the biggest burner for lighting his workshop stove thats all its good for.

> Sorry Neil but i don't think the cook's torch will generate enough heat here for silver solder.

Might not there Shaun, but it does here

I've just used it to tin the end of a coil of 3/156" cunifer pipe with silverflow, it's at the limit for it, but it gets it red hot surprisingly quickly.

For really small things I have a turboflame lighter.

Neil

Fair play Neil, however Mark's, cones are a bit bigger. I perhaps should have made that clearer. As I'm sure you know most flames are roughly at the same temperature it's the amount of gas burnt that gives the heat. For anyone interested Keith is writing a series of articles starting in the August edition of Engineering in Miniature on 'Heating for the Model Engineer'. (Can I mention that on here???)

Hi Shaun,

You've got your metric head on If I had typed it properly 3/16" (not 3/156" pipe is bigger than 5/32"! The cone itself will barely matter as it's the amount of heat running away down the pipe that has to balance with the heat input.

I've seen my torch for sale at £38 as a 'small brazing torch' - but there are obviously various versions of a cook's torch and some will be bigger than others.

Neil

Hi all, sort of thinking outside the box idea I am experimenting with ...Loctite 603 high strength fixative...it appears to work and no leaks under steam pressure...be sure and wear safety glasses if trying this for your selves.

All the best for now,

John.

What pressure steam? as too high and the temp will be over the working range of 603

I do not think Loctite in this situation even the high temperature retainers is suitable.

Hi All,

Plenty of information on this subject! Most grateful for the input,its an intreasting subject and i shall be looking out for Keith's article next month!

Shaun, i just checked out the new handyjet torch, looks perfect for those little jobs, think i shall invest in one

Cheers one n all

Mark

opps! should have read "I do not think Loctite in this situation even the high temperature retainers are Unsuitable".