Connecting 1 1/2" waste to 40mm waste

[Deleted member 137318]

Hi, I'm sure this question has been asked/answered somewhere but I can't seem to find much.

I have a shower tray to fit which has one of those flexiwaste devices attached to the trap - see here: http://www.toolstation.com/shop/Plu...+12+Uni+Outlet+Plain+Spigot/d20/sd2907/p75951. My problem is that I need to connect the spigot to a 40mm waste pipe. I can't find anything on Screwfix or Toolstation that will do the job, apart from maybe a 40mm Compression Straight Coupling. Would the 40mm compression tighten enough to seal around what is effectively a 38mm (1 1/2") spigot? Are there any other ways. Utopia for me would be a 1mm thick sleeve that allowed a solvent weld to take place.

Last question, why can't I just buy a 40mm flexipipe? and why are we still selling imperial fittings - OK that's 2 questions

 

[summertheplumber]

a mechanical connector will seal down to that size, nip it with grips n if it doest spin in joint uve got a fair gud chance of seal, if not its amazing what a ptfe tape washer can seal

 

[tamz]

They are not selling imperial fittings. 1 1/2" and 40mm are the same thing just different speak.
Take the spigot (plain) end and see if it fits the compression end. Surprised?
Buy a 40mm (1 1/2") multifit union or bend if needed but the purpose of these fittings are to connect the flexi spigot to the trap leaving a compression outlet.
You should have bought a flexcon 4 if it was for pipe to pipe.

 

[Deleted member 137318]

Thanks for your advice - appreciated! I feel a PTFE lash up coming on

Still don't see why they sell them as 1 1/2" - they clearly aren't 40mm. After all all, if Sainsburys sold a lb of apples they's be fined. We've had metric for nearly 40 years now, thought we have it sorted by now (rant over )

 

[TicklyT]

They sell them as 1 1/2" because that's the nominal size of the threads on the threaded components.

Many (most?) metric standard threaded plumbing components produced here and elsewhere in the EU use Imperial BSP (British Standard Pipe) threads. 15mm fittings usually use 1/2" BSP, 22mm uses 3/4" BSP etc. etc.

Perversely, before metrication, many brass components produced in the UK used BSB (British Standard Brass) threads, which almost matched the metric extra fine range of threads.