I measured the flares and established they would fit inside 50mm waste tubes. I could not buy 50mm tube at B&Q, so I had to order all the fittings online. 3m of tubing, and four screw ends duly arrived (they didn’t have blank ends, so each end would have a screw cap).
Got everything together and realised there was no way to join the screw ends to the tubes. Back online and order four couplings, plus a hefty standard delivery charge. I even remembered the solvent cement.
The flares fit inside the 50mm tubes. But the internal diameter of the screw ends, while listed as 50mm, is not 50mm. It’s a couple of millimeters less. As you can see from the photo, it makes all the difference. The flare won't side through.
Anyone doing any plumbing? I have some waste tube you can use.