I am stripping out the downstairs bog and there are plastic isolation valves on the hot and cold water to the hand basin. They have markings on which look like JS but the font is naff. They have long bodies and are marked 65 degrees c max. Where the pipe enters the valve end there is a moving collar, indeed the pipe can rotate within the valve without leaking. I will replace these during the re-furb but wondered whether it should be possible to remove the downstream pipe. I have tried pushing the collar towards the valve to release the pipe (as with hydraulic/air fittings) - the collar appears to move, but the pipe remains fixed. Anyone used these and know if they are demountable (they don't appear re-usable, not that I would anyway).