I'm not one of those, but I checked google.
It seems there are an awful lot of different PVC types, with different
characteristics. there might be PVC's designed to take pressure
(and pressure fluctuations). but do not expect your drainpipe to have those
the link below explains the behaviour of (some type of) PVC with
temperature, which is probably what we want to know.
NOT GOOD for the application of propel, although the problem is apparently
not in letting the tank stew under the sun, but rather the low temperatures when filling..
hope that helps.