Maximum pressure of waste pipe (2023 Update)

[timegoesby]

Does anyone know the maximum pressure 42mm or 50mm plastic waste pipe can hold when jointed by solvent weld glue? I can't see anything on the web sites.

TIA

[Grunff]

If you're asking about rated max pressure, then there isn't one - they aren't designed for pressure operation, and should only be used in open systems.

If you're asking how much pressure can they really take, then I've used

42mm pipe as a reservoir at 5 bar without any problems. That was for air.

[nightjar]

You won't, as they are only designed for use at atmospheric pressure. Anything higher is entirely at your own risk.

Colin Bignell

[Doctor Drivel]

"nightjar .uk.com>"

They are designed to take a maximum pressure as drain pipes under heavy use in a building with 3 or 4 floors can have a quite a bit of pressure on them. A building that is 50 foot high with block drain all up the stack has quite a pressure at the bottom of the stack.

There are solvent weld plastic pipes on surface water systems, usually on farms and in industry. I don't know much about this stuff so can't help. I recall reading that solvent weld can take 1 to 2 bar, but the makers are the people to contact, as there is about three types of PVC pipe. I am surprised this info is not on their sites.

[nightjar]

You shouldn't be using 42mm or 50mm pipe to drain a 4 storey block of flats. They should be feeding into a vented stack of at least 100mm diameter and a blockage at the foot will only have the back pressure generated by the height necessary to overflow the lowest outlet on the ground floor.

Colin Bignell

[Doctor Drivel]

"nightjar .uk.com>"

Not if the toilet is way high and the only one. It could be a loft extension and an en-suite. I was on about the solvent weld, not particularly the pipe size. The pipe itself will take quite a pressure before it pops. 5 bar was given here, and no problems in weld and pipe.

[nightjar]

The pipe size is relevant, as different British and International Standards apply to different sizes, materials and applications of waste pipes. My initial comments applied only to small bore pipe as usually sold for use as waste pipes.

That is fairly meaningless unless we know the pipe size, material, grade and application and whether those are in any way related to the pipe being used by the OP. That pressure is, for example, more than ten times what should be applied to 100mm - 400mm underground pipelines during a water test.

Colin Bignell

[Doctor Drivel]

"nightjar .uk.com>"

~30 foot is 1 bar. 1 bar is well ....1 bar, irrespective of pipe size.

[nightjar]

As I said, that is fairly meaningless information without knowing the pipe size, material, grade and application. Some pipes are designed to accept that sort of pressure, while others will be overstressed by it.

Colin Bignell

[Pieter]

I have 160mm soil pipe and I'm looking to use them for my micro hydro turbine with a 20m head. Any thoughts?

[Colin Bignell]

Soil pipes are vented to atmosphere, so do not have a pressure rating.

[The Natural Philosopher]

True, but that doesn't mean they can't take any pressure. If solvent welded they can certainly handle the sort of 28psi that the base of te pipe will be subject to. If in any doubt get a section and fill it with water, seal it and presurise it to that level - you can hire pressure gauges and pumps, and using water is safe if it splits

[Colin Bignell]

Obviously, they need to be strong enough to resist the weight of soil. It is just that nobody publishes pressure ratings for them.

I would add at least 50% safety margin myself.

- you can hire pressure gauges and pumps, and

Even safer if you do it under water, as with the Comet cabin testing