Losing the plot regarding sizing.

[Bogart]

All was going well with installation of sink and washing machine until I came to connect the waist from the sink to the existing pipework. Have a couple of push in fittings marked 38mm which I thought would be the ones. They do fit the pipework exiting the house. Problem is the piece of pipe which I thought was the same size is very loose in a push fitting. so am short of a bit of pipe from the waste fitting to connect to existing pipework. Is okay in compression one.
Have some 40mm solvent weld pipe for on outside job that fits buggar all except solvent weld fittings.
So I have a push fitting marked 38mm do I buy a length of pipe listed as 40mm but not a solvent weld one?
Going outside for a beer.

 

[Aquarius]

Probably easier to renew the lot in push fit (41mm) or solvent weld (43mm). Not heard if 38mm in the uk, even with basin fittings (34mm push fit and 36mm solvent weld)

 

[Chuck]

Solvent weld 40mm system is larger than 'normal' by a couple of mm to prevent people mistaking the types.

40mm is the nominal od of the normal pipe, it's typically more like 41mm in practice. 38mm is the internal diameter of the 40mm pipe and is how fittings are identitfied. (Used to be 1-1/2" ID)

The push fitting should feel a bit loose (i.e. not tight) to allow for some 'play'.

If you want to the nicest results, buy pipe and fittings from the same (reputable) manufacturer. I like Marley but FloPlast or Polypipe also have their fans and may be easier to get hold of.

 

[Bogart]

The 38mm fittings are from Toolstation so am assuming if I buy a length of non solvent weld pipe all should be okay.
Still leaves me unsure as to the size that is a loose fit in the 38mm push fit but fits okay in a40mm compession fitting.
[automerge]1597003536[/automerge]

 

[Aquarius]

Just been on Toolstation website, can’t find them. Even typed in 38mm which returned 5 results. I think @Chuck has given a better description than I could, unsure myself why it would be loose in pushfit, but ok in a compression fitting. If you have all push fit go with that, or swap for solvent weld

 

[Bogart]

i have to go with what currently exists as is hidden behind un its and cannot really start changing all that. Here is the 90 deg fitting I got

Push Fit Bend

www.toolstation.com

States 40mm but fitting marked 38mm, but it fits the current pipework fine. Am not sure thewn what size the pipework I was going to utilise is. The above fitting just falls off it the pipe is turned upside down, and it is definitely not 32mm pipe. I will just get a new lengthe of'40mm'pipe.

 

[Ben-gee]

Cut out what you need to to make your alterations then use a McAlpine multifit 1 1/2” compression fitting on the old pipe. (straight or 90 degree, as required).

Then go from that point in new fittings/pipe of your choice (we would all use solvent weld).

 

[Bogart]

Funnily enough just bought the exact fitting you mention. Great minds and all that
[automerge]1597077789[/automerge]
Just fitted all sorted. Thanks guys.