I'm looking to insulate some 3" CPVC Sched 80 pipe and 90 degree elbows. I know the O.D. of 3" copper is not the same as the plastic and not sure if is the same as black pipe. Therefore, without the knowledge of the various O.D.'s of the different materials, I was hoping to purchase the 1/2" thick fiberglass sheets of insulation instead of the pre-formed/pre-slit sticks. Does anyone know where I can find such material or advise on the O.D. of CPVC versus Black pipe?