Replacing a section of pipe

[Dendyver]

Whilst leveraging a shrub from near the property, too much pressure was put against an almost horizontal 40mm gauge circular plastic pipe attached to the property wall, which carries waste fluid from the washing machine.

As a result of this wild gardening, a section of the pipe is now cracked and I need to cut out about 60cm, replace it with new piping, and fix it in 2 places to the existing pipe run.

So, I have new piping, and 2 sleeves to cover the joins.

Before I start, can someone recommend, how I would seal the new joins?

Thanks

[Itsallaguess]

So, I have new piping, and 2 sleeves to cover the joins.

Before I start, can someone recommend, how I would seal the new joins?

What type of sleeves are they, or are they just basically 'slightly bigger pipes' that will slide over the waste pipe itself?

Do they not have any sealing properties as part of the sleeve design?

Are you able to provide a link to a photo of the sleeves so we can get a better idea of how they'll work?

With the above said, remember that there's going to be almost no actual 'pressure' on this waste-water drain, so if the sleeves themselves don't provide any mechanical seal, then perhaps a clear external silicone might be useful for the best finish?

https://www.wilko.com/en-uk/wilko-white-frame-silicone-sealant-300ml/p/0288856

Whatever you do, you'll probably want to provide as smooth an internal-transition between the pipe-joints as possible, with any potential sealant well away from the actual pipe-end joins to try to avoid internal 'lumps' of anything resisting the flow of the waste water.

Cheers,

Itsallaguess

[Dendyver]

Hello

I bought from Screwfix FloPlast Pushfit pipe (53679) and 2 sleeves (60105)

The 8cm long sleeves are a snug fit and in the middle inside there is a ridge which 2 machine cut pipes can but up against and in that situation the manufacturer says a solvent welding is not required.

That is all very well however I am cutting a pipe in 2 places fixed to a wall so my cutting is unlikely to be straight (90 degree angle etc)

Thanks

[bionichamster]

I'm sure you can buy sleeves with rubber seals for this sort of thing. Although if the pipe can be solvent welded that might be preferable.

BH

[jfgw]

First, make sure the straight couplings ("sleeves") fit your old pipe. Waste pipe comes in two types: push-fit and solvent-weld. They are a slightly different size and are not compatible with each other, although you can go from one to the other with big, ugly compression joints. You can usually tell what sort you have by looking at the existing joints. (Compare them with ones on Screwfix if you are not sure.)

If your new fittings fit the old pipe, and if the old pipe is in sufficiently good condition, just cut as straight as you can, clean off any burrs, and push the fittings on. The rubber seals are sufficient without any additional sealant. I would normally apply a little silicone grease but this is a lubricant rather than a sealant. The types of plastic used for push-fit pipe and fittings cannot be solvent-welded.

Push-fit pipe is not as UV-resistant as solvent-weld and it can get very weak and brittle in the sun. Neither sort of pipe normally breaks if it has not deteriorated (try breaking a piece of your new pipe!) so it might be time to replace the whole lot.

If your old pipe is slightly too big for your new fittings, it is solvent-weld (unless it is very old) and you need to get solvent-weld pipe and fittings. These have to be glued together with a solvent adhesive such as this, https://www.screwfix.com/p/floplast-sc2 ... 50ml/14295 .

Julian F. G. W.

[Dendyver]

Hello

The sleeves (straight couplings) will fit over the existing piping.

They have an internal rubber seal at each end, and on the exterior surface at each end there is a plastic ring which one can turn but it does not seem to be on a thread - so it just swivels.

The problem I have just realised is one of the two straight couplings will need to be without an internal butting ridge - otherwise my replacement pipe and couplings is 4cm too long to fit into the gap when I cut a section out of the existing piping.

In that situation, assuming such a coupling exists, I will need to water-proof the join somehow.

Thanks

[Itsallaguess]

Hello

The problem I have just realised is one of the two straight couplings will need to be without an internal butting ridge - otherwise my replacement pipe and couplings is 4cm too long to fit into the gap when I cut a section out of the existing piping.

In that situation, assuming such a coupling exists, I will need to water-proof the join somehow.

Will the existing pipe, at either one or both cut sections, not lift off the wall enough to gain this distance?

I'm not sure why you think you're going to have to 'water-proof the join', as the rubber gaskets on both ends of each coupling is where your seal is being made, and so long as you maintain those rubber seals on a section of each pipe, I think you'll be fine - the internal sides of the gaskets will in effect become part of the inside of the pipe, and will hold the low pressure waste without any issues, and what should be a slight drop in the line of the overall pipe will carry the waste-water away.

Don't forget that this is all push-fit - it's designed exactly for these types of low-pressure-waste installations, so should work out the box so long as you're able to position the couplings central to the join, and maintain a rubber gasket seal on each pipe-end...

Cheers,

Itsallaguess

[jfgw]

If the pipe is push-fit, you may be able to disconnect it somewhere such as at an elbow to allow you to insert the new section. Just pull it apart. I suggest replacing the fitting if you do this. Alternatively, you could use one of these for one of the couplings, https://www.wolseley.co.uk/product/mcal ... nector-15/ . Unfortunately, these seem to be available only in white.

Push-fit is exactly that - you push it together. You do not need additional sealant. If the old pipe is deteriorated to the extent that you do not get a seal, you should replace the whole lot. The fact that it has broken suggests that it may need replacing anyway.

The part of the coupling that you can turn is a plastic collar that is clipped on at the factory to hold the rubber seal in place. You do not have to concern yourself with it.

Julian F. G. W.

[Dendyver]

Thanks for your help.

All is fixed and tested.

I couldn't find a coupling without the central internal ridge, so to overcome the hard to describe problem when marrying up the replacement pipe plus couplings to the gap, I shortened the replacement pipe, so it does not butt up to the internal coupling ridges.

dd