Our old mains water tap seized, so we had it replaced a couple of days ago. The original was brass, connected directly to the blue supply pipe, with a smaller outlet going to a pressure control valve with a pressure gauge. The replacement is as shown in the photo. About 40 minutes after it was fitted, the new copper pipe blew out of the pressure gauge at the joint ringed in red, luckily above the new tap. A call-out saw it replaced again, but the second plumber said the copper pipe doesn't go very far into the valve so the olive is only just held on the copper pipe. Should it have plastic pipe into the valve for better location, or is this OK? I'm paranoid that it's going to blow off again. We need the valve as years ago high pressure blew off an underfloor plastic joint and I really don't want to do that again. What's best? Thanks!