plumbingpushfit
There are many makes of pushfit pipe fittings that make it a lot easer to join pipes, incluing copper pipes, e,g:
(please expand the list if you know of any others)
How do I decide if I should use them rather than soldered copper fittings?
If I use to use a pushfit system, how do I choose the one to use?
In the UK, it's not legal (quite correctly, in my view) for householders to work on gas pipework or fittings at all.
If a buildings inspector or surveyor spots pushfit fittings on gas you can expect plenty of trouble down the line... to say nothing of the risk of a pinhole leak or if there's another fire nearby that melts the fitting.
While you might save a few pounds in the short term, do you want to risk your life and that of those around you? A leaky joint in a water pipe might wreck a ceiling or a floor, the same in a gas pipe might kill you.
Head here for details of the Gas Safety scheme which holds a register of tradespeople who can do the work for you.
Part of the confusion is 'compression' is sometimes applied to fitting types that are not truly compression type. The term should only be applied to fittings where the compressive force is is applied by screw threads via part of the fitting itself as opposed to compressive force being applied by external tools.
In this compression fitting, via the threads seen on the right of the left hand piece and inside the right hand piece, the tapered ring on the copper tube is compressed, squeezing the tube tightly such that leakage is not possible. Plastic tube variants have an additional insert piece that fits in the end of the tube so it does not collapse under the compressive force.
This is an example of a crimp fitting. The ring is slipped loosely over the tube before pushing the tube onto the barbed fitting.
An external tool is used to apply the compressive force to the crimp ring. The material properties of the crimp ring are plastic, so that when the tool is removed, the ring continues to apply significant compressive force on the tube. Note that this tool is carried in the field to facilitate on-site assembly of piping systems.
A swage fitting is yet another type. It is similar to a crimp fitting in that an external tool is used to apply pressure and a sleeve maintains the pressure after the tools is removed.
The major difference is the compressive tool applies much much more force to the sleeve than a crimp tool. A swage tool is typically not very portable and not used in the field. Rather, pipes are pre-fabricated in a shop with a heavy duty hydraulic machine. The types of fittings swaged to pipes typically allow field assembly using common mechanic's tools.
Best Answer
I've been a bit cynical of these but tried push-fit on my last project -- works a treat.
Pros: it's really really fast and easy, you're more likely to get it right first time, and you can use PEX tubing which is lovely and flexible, so brilliant for doing e.g. taps for a basin on a stud partition.
Cons: expensive. Much more expensive. And you'd not want to use them on exposed pipework.