How do you solder brass cones/nipples onto copper pipe

Hmm... and now, in a third attempt maybe you or somebody else can please explain what the strange sentence above really means???

Regards, Frank

i do not approve of soft soldered or loctite joints on steam pipes.

a tip that may be worthwhile is to make up a male adaptor, and add a spare union nut over the cone/nipple to act as a heat sink to avoid localised over heating of the brass cone/nipple. for the other end of the pipe the actual union to be used on the pipe must be used for this.

cheers,

julian

Just returning to the heating issue for a moment:

there's a balance to be struck here, I think. My experience has been that small torches (e.g. the Proxxon small 'cook-sized' torch) are very handy for tiny jobs, but will not do for larger jobs or for jobs where more heat is required such as copper pipe. I have a larger propane torch (Sievert, I think; but very old) which has a fine jet or a broad jet. That's a better bet, and can also be used along with the Proxxon. Of course then you need 3 hands... I use that combination for hardening and tempering small jobs.

Then there's the oxy-acetylene... which inevitably just melts small jobs. Wonderful tool, but not for nipples.

I thin it best to have adequate heat, and some in hand, because one factor is the ability to bring the work to temperature quickly. If it takes too long the flux will boil off. Once the flux has gone there's little chance of actually achieving a decent job.

Loctite is wonderful stuff and I use it often, but have not used the high temperature stuff.

Grade 4090 says it is ok to 150 degrees C, but I have not used that product. Others are ok to 100 deg C.

Marcus

That's a good idea, Julian. The bits that are most prone to overheating seem to be the sharp ridges or the corners, and the very fine end where the tapering cone meets the pipe, so the mating adaptor would cover those. I can also recommend putting the assembly inside a larger steel tube and heating that, so the pipe and nipple receive only indirect heat.

Marcus

On larger sizes of pipe, the Sievert Cyclone Burners work very well

... although seeing the current price was a shock.

Does anyone know of a "micro" size burner with a similar wrap-round flame?

MichaelG.

Too late to edit previous post ...

Here is the smaller of the two Sievert Cyclone Burners [19mm dia.] ... This one is ideal for domestic plumbing; but something half that diameter, or a little less, would be nice for small work.

MichaelG.

They do make a 14mm cyclone but I think it fits a different torch body

Silver soldering is not a black art as people imagine, here is my fool proof method.

1. Apply flux paste to pipe,

2, Insert pipe into nipple.

3. Heat pipe just above nipple,use slightly carburising flame(soft).

4. Apply solder to job, don't melt solder with flame let the temperature of the job melt it. Use just enough to do the job,(remember silver solder is expensive) I would recommend using the smallest rod you can I find 455 at .7mm ideal for nipples.

5. When solder has solidified dunk in DILUTE sulphuric acid to remove flux, wash in water.

Hope this is of use to you. Mark P.

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Jason

Thanks, but that's still rather big compared to what I had in mind.

For small work; I am intrigued by the possibilites of Resistance Brazing ... I have a suitable Transformer, so making some handpieces is definitely on the ToDo list.

MichaelG.

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Edit: Just found this old but useful info. from Johnson Matthey

Edited By Michael Gilligan on 11/07/2014 15:18:40

Edited By Michael Gilligan on 11/07/2014 15:34:34

Just a thought. Many years ago I tried to solder gunmetal oil banjos onto copper tube using some scrounged high temperature solder. The oil banjos kept melting as soon as I applied solder. Oh the joys of metallurgy - eutectics and all that. As soon as I tried ordinary "easyflo" solder I had no problems.

JA

I also use one of the cook's blowtorches to light the propane torch. I found I kept blowing out matches and tea lights even with the gas turned down. With one of these little blowtorches you can turn it on, ignite the flame and turn it off again with one hand. Also handy if you fancy a Creme Brulee in the workshop

Gary

marcus bowman and mark p. have provided excellent advice. i've silver soldered hundreds of cones/nipples to small copper tube in the last 31 years and never had a problem.

you need to know what the flux looks like when the job is up to temperature! a diffused light helps gauge the temperature of the parts being heated, but not so dark that you cant see the changes in the flux. ive a full set of sievert burners on my propane, and for small jobs avoid the very small burners with a very concentrated flame. i go up a few sizes to a medium sized burner for a soft gentle overall flame.

when the flux changes to the correct state you have only a few seconds with small bits such as this to apply the silver solder! 'flash' and done!

cheers,

julian

Edited By julian atkins on 11/07/2014 23:48:33

Edited By julian atkins on 11/07/2014 23:48:48

Mark,
I think you need to find someone that lives close enough to you to give you a demonstration of how things look when silver soldering. (Estimating temperature, flux flow and silver solder flow.) I think silver soldering is just like learning to ride a bike. Once you can do it it seems so simple. If you are not prepared to give an idea of your location so someone can offer to show you the technique then go to one of the shows where cupalloys have a stand. They may be doing a demonstration.

Les.

Mark,

You will certainly find CuP Alloys at Bristol, Midlands, Ally Pally, Harrogate, Bakewell, Spalding.

Keith

Keith (CuP Alloys) ....when are you at Spalding?

Mick

One tip, if you are melting things, if silver soldering outside, always do it in good shade.

Neil

Hi all, Marcus I contacted one of Loctites technical gurus last week and explained that i was experimenting with loctite 603 ,using it to retain the usually silver soldered nipple (sleeve)on to the end of a pipe..I gave the dimensions of pipe ,steam pressure and he worked out that it was feasible ...603 held to 150*c but as he could not give the temp at the actual nipple , he would much prefer to use 648 loctite as it goes up to 175* c...so i said i would try that and let him know the results properly prepared it should be a good job...

The whole idea behind this experiment is not that i am not able to silver solder a nipple on to a pipe...I most certainly can and make a good job of it ...BUT...when my hands are tremoring with the effects of Parkinsons ...Forget it....If i can verify the idea does work safely i will use it.

All the best for now.

John.

Yes; Loctite technical staff are very helpful. I do know that Loctite works best when the parts are pushed together under a light interference fit, so it may be possible to machine the nipples for that condition to apply. The idea is to exclude air, and it seems this works best when the film of adhesive is sheared as the parts go together, leaving the bond to be made by very thin layers of adhesive which are left in the microscopic interstitial spaces between the components. I always thought I should leave a little clearance for the adhesive, but, having taken advice about replacing a press fit between two components by using Loctite, the advice I as given was t go for a light press assembly, having first coated the mating surfaces with Loctite. Worked extremely well, and the components are still together, despite heavy loading of the joint.

In the case of a nipple, I would guess that a light finger-push fit is what would be required.

It might also be a good idea (and a slight complication) to ensure the tube was round and of the correct diameter, perhaps by inserting a rod, and squeezing the outside of the tube very lightly between two halves of a hole. Clamping two rectangular blocks together, and drilling a hole down through the joint would give an accurate former.

I think all of this is, as you say, a very interesting experiment. It also highlights how developments in adhesives challenge our preconceptions.

Marcus