I was doing some maintenance of my irrigation system, replacing sections of pvc schedule 40 and 80, 1/2" and 3/4". A stock of material I've had sitting around for at least 8 years seems very brittle, cracking under the pressure of my ratching cutter. Normally my cutter cleanly slices through. Does this stuff age to a point where you shouldn't use it? Should I throw it away and buy new material?