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fluxing pipework and fittings prior to soldering

which fluxes are active . was told on original gas training at college not to use them on gas pipework but nearly all are active now but to what extent
 
See my post on 'neat soldering' on another thread.

Fluxes like laco are fine. Only flux pipe and twist, remove excess flux from external pipe and fitting with dry cloth. Then solder.

If the fitting is clean, then there is no need to apply flux to it. Excess flux on the inside, due to fluxing the fitting will lead to high ph levels in the system, unless thorough flushing is carried out. If flux is not flushed from the system, it increases the risk of electrolytic corrosion in heating systems, leading to higher levels of corrosion e.g. pin-holes in radiators. There is less of risk for cold and hot water systems, where the flux is flushed through the tap - however, a few years ago a whole building site was shut down because of green gunk in the bath cause by flux in the system. The house buyers had to be put-up in hotels until the site was cleared and water safe to use.

Hence, one could present reasons for fluxing the fitting, but I could give you more 'scientific' reasons for not fluxing the fitting.
 
I'm a pipe only bloke applied with the finger of course and a twist at the end 🙂 A guy I was watching a while back marks the 'full slip' point before inserting the pipe for the last time! A bit OTT I thought but each to their own 🙂
 
diamondgas said:
I'm a pipe only bloke applied with the finger of course and a twist at the end 🙂 A guy I was watching a while back marks the 'full slip' point before inserting the pipe for the last time! A bit OTT I thought but each to their own 🙂
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Not OTT in my opinion. I was reluctant to admit I mark the pipes. Let's you see the pipe is full in, as you would with push fit, but also means you will notice if the pipe starts to slip back out.
The flux can make the pipe easy to slip back & as you apply heat, also pipe can slip back sometimes. Pipe just needs to be under very slight strain & usually are.
I first flux pipe, then mark roughly past the full in point on the fluxed pipe & then push together. I was taught to always do this by a very professional plumber.
I don't want to nicely solder a fitting that the pipe is just inside it by a few millimetres!
 
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Best said:
Not OTT in my opinion. I was reluctant to admit I mark the pipes. Let's you see the pipe is full in, as you would with push fit, but also means you will notice if the pipe starts to slip back out.
The flux can make the pipe easy to slip back & as you apply heat, also pipe can slip back sometimes. Pipe just needs to be under very slight strain & usually are.
I first flux pipe, then mark roughly past the full in point on the fluxed pipe & then push together. I was taught to always do this by a very professional plumber.
I don't want to nicely solder a fitting that the pipe is just inside it by a few millimetres!
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The guys I was with were ex colleagues from BG now working, like myself, for themselves 🙂 As you say, very much the text book professionals when installing. I'd never learned the marking thing otherwise it would have been part of my repertoire most likely! I've actually employed them to put heating in my home because I knew they'd do a better job than me 🙂 I'm a repair engineer primarily and, although I have done and can install, I couldn't do as good a job as they .... There's honesty for you! 🙂 Thanks for the explanation as to the reason why you mark 🙂 I understood the reason but never gave it that much of a consideration considering I'd never used the technique in all the years I've installed 🙂
 
fitting for me, I know its technically wrong but I raise my middle finger to that. I use hardly any flux, and as tamz said it will run into the pipe whatever method you use.

Talking of marking pipes and fittings popping off reminded me of soldered cap ends popping off when being heated 😀 used to wind me up until I figured a tap with a hammer or squash with a pair of grips kept them on!
 
sambotc said:
fitting for me, I know its technically wrong but I raise my middle finger to that. I use hardly any flux, and as tamz said it will run into the pipe whatever method you use.

Talking of marking pipes and fittings popping off reminded me of soldered cap ends popping off when being heated 😀 used to wind me up until I figured a tap with a hammer or squash with a pair of grips kept them on!
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Agree!! I just use compression ones now. I can't bring myself to leave speedfit stop ends in as a permanent fixture. Just looks like an accident waiting to happen.
 
Marking the pipe has probably evolved from plastic. If you use plastic, then you mark the pipe. Doing it for copper is not needed, but if its done, it does no harm.

For fittings that slide off while soldering, this is down to soldering a closed system. As the heat in the pipe warms the air inside the pipe it expands, pushing the stop end off. Possible solution - open a tap on the system to prevent any build up of air pressure.
 
Soldered caps pop off due to a build up in pressure when heating them. Solder them first with an open end and they stay put.

I agree, no way would I rely on a pushfit overnight. I go to extremes and even use a screw on brass cap on isos. Prevents a flood if kiddies tamper with them! Helps keep the dirt out too.
 
sambotc said:
Talking of marking pipes and fittings popping off reminded me of soldered cap ends popping off when being heated 😀 used to wind me up until I figured a tap with a hammer or squash with a pair of grips kept them on!
Click to expand...
Just be careful when you are soldering any fittings on short runs to make sure there is an open end on the pipework somewhere, especially if it is a tiny piece of pipework, as the air inside will expand & blow out the solder - or the soldered end caps off!
 
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system3 said:
Soldered caps pop off due to a build up in pressure when heating them. Solder them first with an open end and they stay put.

I agree, no way would I rely on a pushfit overnight. I go to extremes and even use a screw on brass cap on isos. Prevents a flood if kiddies tamper with them! Helps keep the dirt out too.
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Just beat me to it! :smile:
Good point about those push fit caps, I would rather waste an olive for a temporary cap, than risk those push fit. The Speedfit caps, handy that they are, can very easily be accidentally pulled off.
Iso valves, rad valves, gate valves, I would plug off for safety also. If they pass a bit, or a vandal or kid tampers with them, plumber gets the blame.
 
i carry a few doc's with nuts/olives on which i use to cap off rad valves or compression fittings. I find this is best as i often in the past wished id left a drain point.
 
Clanger said:
Marking the pipe has probably evolved from plastic. If you use plastic, then you mark the pipe. Doing it for copper is not needed, but if its done, it does no harm.

For fittings that slide off while soldering, this is down to soldering a closed system. As the heat in the pipe warms the air inside the pipe it expands, pushing the stop end off. Possible solution - open a tap on the system to prevent any build up of air pressure.
Click to expand...

Fittings can slide off a bit when soldering on open pipes also. This is caused when a pipe that has any tension on it, is held by the flux in the fitting, but when heat applied melts the flux, the pipe can release, - if a pencil mark is on the pipe it is very obvious. I see this often.
If you push pipes into a soldered fitting & then move the pipes exactly straight, level, whatever, the pipes often move out a bit, so how can you tell if pipes are full in if no pencil marks?
 
If you get stuck for a screw on cap, put a 5 pence piece inside a brass nut with a fibre washer.
 
I had 1 blow off on a revamp,it was ok for an hour or so then came off ,when i checked the fitting i found it had a hairline split in it,the manufacturers got an ear bashing and i got freebies
 
I must be the only one who can't get those bloody speed fit cap ends off even when I'm trying hard to then. In fact speed fit stop ends are the only push fit fitting I use! Only for temporary capping though.I've used hep before in lofts were the last company I worked for had a no hot works in loft policy. Never as far as I know had a problem with it, never penciled a mark on that pipe either!
 
Use some silicone grease on the Speedfit caps to help get them on & off.
Try turning them while you hold the collar in & are trying to pull them off.
Or, if all else fails, do as I do & tighten a large adjustable on the pipe & batter the collar end till the cap comes off! :smile:

Just realised this thread about fluxing has drifted to push fit! Lol!
 
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system3 said:
Soldered caps pop off due to a build up in pressure when heating them. Solder them first with an open end and they stay put.

I agree, no way would I rely on a pushfit overnight. I go to extremes and even use a screw on brass cap on isos. Prevents a flood if kiddies tamper with them! Helps keep the dirt out too.
Click to expand...

Only cos you're too tight to use the 5p trick 🙂

**Edit**
Oops - just saw your follow up post....
 
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I always end up having issues trying to get the speed fit caps off. I shall start using the silicone grease method from now on.

Discovered the spanner trick after struggling for around 5 minutes to get one off.
 
I'd worry that greasing a pipe that you want a push fit fitting to stay on is counterproductive. Friction keeps it on, grease reduces friction. But I'm no expert. Fear will keep me safe from flooding a house though!
 
I do not use use push fit, except where existing work is plastic & needs repair, or plugging heating expansion pipes etc. A lot of push fit fittings are slightly greased when they are new. The gripper should still grip the pipe hard. I noticed that a new Tectite connector I was looking at, had a large lump of silicone grease stuck inside it, to one side. Bit too much frankly. Only needs a slight dampness on the O ring.
 

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