Undoing and re-making soldered copper pipe...

[Mike Armstrong]

Hi all,

I'm fitting my new boiler this weekend.

In order for the gas supply pipework to be sufficiently sized I am replacing the final section of 15mm with 22mm.

The 22mm pipe runs under the concrete floor, through a swept bend vertically up the wall to about 500mm from the floor where it is reduced by a soldered 22-15 reducing connector to 15mm pipe. it continues from here to the boiler.

The original installer has hacked a channel in the plasterboard dry-lining and the pipe is set into this channel with a few mm clearance to the blockwork wall behind.

This is all going on behind by kitchen units and I have created an access hole to get at the joint.

I would normally cut the pipe and use a 22mm connector to extend the

22mm pipework, however access is extremely difficult. There is little or no flex in the pipe to use my pipe splitter and the fact that it is recessed behind the plasterboard makes using a hacksaw pretty impossible.

I am wondering whether it would be easier to apply heat to the reducing connector to 'un-make' the joint. The question is how hard is it to clean up the 'un-made' end in preparation for the new 22mm straight-through connector?

Once cleaned up would another soldered joint be necessary? Compression would be easier!

Cheers!

Mike

[BigWallop]

Gas pipework must be soldered, especially if fitted in an un-accessible position, Mike. Compression joints on permanent gas pipes are not the way to go unless you can get at them easily.

[Andrew Gabriel]

Redoing a joint like this which was done OK originally is not difficult. You don't have to clean the pipe end up, just make sure the pipe end is tinned all the way round (i.e. that it was a good joint originally). You might not be able to push the coupler over the solder. In this case, you will have to heat the pipe end in order to push the cleaned/fluxed coupler on, and then heat the joint as normal until solder flows and add a little more to make up for that lost in the reducer.

Redoing a joint when the original was not OK is harder, and would require the pipe end to be cleaned up (and a new fitting as it's generally not worth cleaning up an old one which failed to solder correctly in the first place).

Not allowed for gas in an inaccessible or confined space. Are you sure you are competent to do the gas side? Don't forget to do a soundness test before and after (so you know if you've introduced a leak, and/or if there was originally a leak which you need to go and find).

[Mike Armstrong]

The joint is OK. I did a pressure drop test when fitting our gas fire last week.

So the procedure would be :-

1. Heat existing reducer and remove (with tongs!)
2. Cleaing and flux the new 22m pipe end
3. Clean and flux _both_ ends of inside of new 22mm connector
4. Mate new pipe and new connector ready to heat.
5. Heat old pipe end to soften existing solder
6. While still hot, lower new assembly onto pipe and continue to heat until joint is made, adding extra solder if necessary.

Clearly, I will be carrying out another soundness test on completion.

[Cicero]

================ Does it matter if the solder types are different? On the rare occasions that I've had to do as the OP is doing I've always cleaned off the old solder completely to avoid any incompatability.

Cic.

[Andy Wade]

When you get the old joint apart, wipe the end of the pipe with a slightly damp cloth while the solder is still molten (use a swift motion, to avoid cooling things down). This will remove surplus solder and leave a nice clean tinned end for the new joint. It's similar to cleaning the tip of a soldering iron on a damp sponge.

[Mcluma]

Yes you can solder the old off, clean it up with sandpaper, and put th

new one back on - with solder, finish it off, and check with fair liquit for leages, or even with a lighter (yes i actually have see them doing that- though I wouldn't recommand it)

Well if you space it limited, it is also dificult to put a compressio on it, so that is then ruled out,

To cut the pipe there are these nice round 22mm cutter that only nee about a 1,5cm clearance arround the pipe

Succes

-- Mcluma

[StealthUK]

difficult.

originally).

cleaned/fluxed

Yep, the only thing that normally hinders a new coupler going on is a lip of solder at the end of the pipe. I also just heat the end of the pipe and wipe round with a cotton cloth, although not damp in my case.

[nthng2snet]

If the joint is in a tight place and or tight up against a wall then a heat resitant mat might help. It takes the concentration of fitting a joint like this way from the flames that are burning the wall.

[Tony]

read your boiler insructions

I cant think of any domestic boilers that require 22mm supply unless the pipework is a very long way from the meter and has lots o bends , you will need to get your work checked , please dont turn the gas bac on until a tightness test has been done

-- Tony

[Simon Stroud]

ISTR that the instrument of choice in the old BT or probably PO lead cable jointing days was a moleskin rather than a damp cloth!

Not sure if they keep those down at B&Q!

Good luck. Simon.

[Paul Barker]

Obviously you shouldn't be doing this at all, because if you wer qualified to you wouldn't be asking the question. Howver let me poin out a few obvious mistakes which would fail you on your pipewor practical during ACS assessment.

1/ Before we solder a gas pipe we cap off the meter (best not just t disk it, put a proper cap on it or remove it completely and turn i upside down or put something suitable over the two holes to prevent th gas escaping, without which there is a very real danger of explosion This explosion could easily cause a mortal injury and damage t property. 2/ Connect temporary earth bond upstream first then downstream an then break into the pipe.

A pre tinned pipe from an old joint is the very best basis of a ne joint.

Make sure you use correct solder.

Most boilers today require 22mm gas pipe.

Pipe sizing is another subject but certainly manufacturers specify 22m minimum, without which they likely won't honour a guarantee.

Like I say you shouldn't do the gas work, but if you are determined t you'd better learn a bit more about it or we'll be watching your hous on news at 10

-- Paul Barker

[Markus Splenius]

When I used to do electronics, we used to use desolder braid. Fine stranded wire that what "suck" up the solder. I don't know if it would work in a plumbing situation - you'd probably need a wide guage!

M.

[Capitol]

Do this joint first, soldering uphill is a recipe for problems.

Regards Capitol

[BigWallop]

A decent chamois leather is good. It's also good at doing smooth wiped joints on lead pipework as well, wet or dry.

[Andy Dingley]

Moleskins for soldering need to be made from good cotton moleskin and lubricated with tallow. Proper moleskin works a lot better than even denim or corduroy. I've been trying lots of different fabrics lately as lead-wiping moleskins, cotton, linen, wool, even Kevlar and asbestos. You can't beat the traditional stuff.

And yes, I have even tried using Mole. I really don't recommend that.

[John Rumm]

A good number do... anything over 30kW will need 22mm for a good proportion of the pipe run unless it is very close to the meter.

See here for information on pipe sizing:

[Mike Armstrong]

Thanks for all the replies to my question. Clearly re-soldering is the way to go.

For peace of mind can I state that:-

I have calculated the pipework sizing requirements (this is why the

15-22 change is needed)

I _will_ be disconnecting the gas pipework from the meter and clearing the gas from said pipework.

The pipework _will_ be earth bonded while the work takes place.

Once coplete the pipework will be tested for soundness using pressure drop test (at 20mb and also 5 and 10 looking for pressure rise to ensure that no gas is leaking past the shut-off lever)

The gas pipe will be be fully purged.

Thanks again for all your help.

Mike

[Paul Barker]

Good to hear, well done

-- Paul Barker

[Mark]

Ha Ha and in the real world. Contractors are replacing gas main and laying new plastic gas pipe inserts into houses in town. Technique: dig hole, wrap live gas pipe in denco, cut with hacksaw, HUGE smell of gas, knock blanking plug onto old fitting.