Imperial pipe size mentions in the wiki

[Windmill]

There don't seem to be any.

I vaguely remember that someone once posted an article about compatibility of metric adapters etc. with old imperial pipe sizes, but it would be nice to see some mention of it in diyfaq.org.uk

Especially as I just discovered that you can't make a decent solder joint from copper pipe diameter somewhere about 20mm (so presumably

3/4" nominal) to a temporary 22mm stop end.

But with a good deal of tightening force, a 22mm compression stop end managed to withstand mains water pressure.

I had what I thought I needed in the way of solder ring and end feed couplings, adaptors, etc. but panic set in when I realised I couldn't get a proper seal to them.

I don't often thank God for B&Q but I did yesterday.

[fred]

In article , Windmill writes

That comes as a surprise, the 3/4" pipe I have in the bin here is 21.5mm external and the small extra clearance is easily accommodated in soldering. (3/4" or 19mm nominal bore plus 0.8mm wall).

Do you know about imperial conversion olives? These are internally sized to suit the o/d of the imperial pipe and work really well with 22mm fittings.

Was the solder stop end a particularly sloppy fit? Perhaps you had a weird in-between pipe size.

Do you normally find soldered pipe joints easy? Nice and clean (wire wooled) plus plenty of flux? End feed or solder ring? Any extra solder added?

[Roger Mills]

As you say, you can get special olives to use with 3/4" pipe in 22mm fittings, and they work really well.

In my view, it's dodgy trying to use a 22mm solder fitting on 3/4" pipe. You can get special couplers with 22mm one end and 3/4" the other. They wouldn't exist if it were easy to do without.

The difference in diameter between 15mm and 1/2" pipe is much smaller - and you can often get away with regarding those as interchangeable.

[Andrew Mawson]

As a temporary work around I used to expand 3/4" pipe with a suitable Rawlbolt after annealing. It needs placing twice so that the three limbs of the Rawlbolt give six outwards expansions and then the pipe solders satisfactorily into a 22mm fitting.

Andrew

[Roger Mills]

Novel! Sounds a bit hit and miss, though! I suppose you get to know how much torque to apply the rawlbolt.

You used to be able to get (probably still can) a tool for expanding the end of a pipe to enable another pipe of the same size to fit inside - as a means of joining two pipes together without any fittings. I suppose that expanding a 3/4" pipe to 22mm sounds mild by comparison.

[Andrew Mawson]

About the same time I made one of those tools - simple turning job. Made one for 1/2" 3/4 & 1" pipe - still got them somewhere. Needs well annealing and it's easy to end up with a socket that's not quite co-axial with the pipe. Incidentally the Rawlplug trick wasn't really hit and miss when you'd done it once or twice - only a little expansion needed - hardest bit was getting a clean end on the pipe - if you used a normal pipe cutter the burr gets in the way.

Andrew

[John Rumm]

An article on coping with non metric and or non standard pipe sizes might be nice.

I have found you can get a decent compression seal on 3/4" pipe using a normal 22mm fitting and olive in many cases - you just need to do it up "more" than you would normally since the olive needs far more compression to fit the pipe.

I also once did a hack with a 22mm end feed fitting - running the pipe cutter round it so as to place a couple of annular dents into the fitting and thus reducing the internal diameter a bit. I could then solder up a sound joint between 22 and 3/4" pipe.

[Nightjar]

and, perhaps on the difference between pipe and tube :-)

[Johny B Good]

Or, even the difference between 'pipe' and 'washers' :-)

[The Other Mike]

Only ever used the 15mm one and they are a bastard to use in situ

[Windmill]

I'll try to remember that. Though I normally use a non-adjustable cutter, which wouldn't fit.