Maximum pressure

[Dave Plowman (News)]

Does anyone have figures for the maximum pressure a normal domestic soldered copper pipe system (15mm) would be expected to stand?

And a sort of safe working pressure.

[Richard]

[The Natural Philosopher]

Pretty massive. I'd expect 10 bar to be the area where problems might start to happen.

I pressurised my UFH (plastic pipe, O ring seals) to 8 bar without issues.

Of course there are generally pressure relief valves in place somewhere.

1-2 bar typically.

[Tim Watts]

At least 10 bar at a minimum - this is a figure that is often found as the max working pressure for boilers (on the potable side) and other devices (noting that certain devices may be limited to 6 bar, eg instantaneous water heaters).

[Nightjar]

It is American, so in fps units, but the Copper Tube Handbook contains all the data you are likely to need for various types of tube and joints:

Pressure ratings are pages 25-28.

[Tim Watts]

WoT?

My mains pressure is 7.5 bar.

[The Natural Philosopher]

My bad, I was thinking of normal primary circuit pressures in heating..usually a couple of bar. Of course mains pressure is much higher...

I should also add that what tends to fail, is not copper or solder butu screwfit and worst of all those pissy isolation valves which always seem to crap out and leak...

[The Medway Handyman]

I don't, but I once sold a pressure washer to a garage who decided to plumb it into a ring main like they used for compressed air. They did it in 15mm copper with soldered joints.

The pressure washer was 150 bar!

Needless to say the joints exploded.

[Dave Plowman (News)]

Interesting - garage air systems I've seen have used iron barrel. Of course that is physically stronger in terms of physical damage.

Right. ;-)

[Dave Plowman (News)]

Thanks for that, Tim. 50 psi would be the absolute max in the app I'm thinking of.

[Nightjar]

You can also get push-fit aluminium or rigid nylon tube for air systems.

Steel pipe is cheaper, but more labour intensive to install and you need to plan the system carefully. It is all right-hand thread, so, if you want to add something, you need to dismantle from one end back to where you want to add the extra connection.

[The Medway Handyman]

The airline was iron barrel. For some reason they assumed copper would do for the water.

[Capitol]

Couplers are your friend.

[Nightjar]

I wouldn't particularly want to cut 2" steel pipe in situ.

[Dave Plowman (News)]

Don't think you'd use 2" steel pipe for the average garage air system..

[Nick]

Are you sure of that? 100+ psi. I've never checked mine but your figure seems very high.

[Nightjar]

It is what I used for my factory air systems, but even cutting 3/4"steel pipe would present problems.

[Tim Watts]

Yes I'm sure. Had a gauge on it.

It is high by mains standards, but we have a lot of hills around here. As I said earlier, most fittings tend to be rated at 10 bar (with odd exceptions) so you could potentially go higher.

Even JG speedfit plastic pipe can do over 10 bar cold and more than 6 bar at ot water temperatures (probably way more - I merely checked that it would work for me, I drop my pressure to 3-5 bar through a PRV before it hits the distribution pipes).

[Dave Plowman (News)]

Used to do a fair bit of conduit work in the day. It was certainly hard work. Chop saws weren't common then.

[The Medway Handyman]

Angle Grinder!