HDPE vs. PVC Why does it have to be HDPE
Under NO circumstances should the thought of using PVC as mortar tubes even cross your mind. One of the most dangerous misconceptions when it comes to consumer fireworks is that you can use PVC to launch mortar shells. A lot of people will compare the cost of HDPE to PVC and say "Well I can just use PVC". The differences between HDPE and PVC is that the inside diameter of HDPE is 1.91". This is the necessary diameter to get the aerial shells to their proper height. The inside diameter of PVC is exactly 2". Even though the difference is only .18" the gases that escape through will not give as much lift. This causes the shell to break lower to the ground compared to a shell launched out of the correct sized mortar tube.
Another difference between HDPE and PVC is what would happen if for some reason a mortar shell "flower potted" or did not leave the mortar and explodes inside the mortar. Inside PVC the mortar shell would shatter the pipe into tiny pieces of shrapnel. Have you ever seen what happens when you drop a light bulb? You will get the same effect multiplied by 1000. Remember with the light bulb it just shatters on the floor...there was no inner force. With a shell inside a PVC mortar tube the shattering force comes from within, sending the shrapnel flying out all over. A lot of firework dealers sell extra pipes and racks. Even though these mortars and mortar racks will cost a little more than it costs to buy a 8ft. length of PVC, is the cost savings really worth the risk of pulling PVC shrapnel out of your face or your eyes? Ther is also the risk of injuring those around you. Please stay away from using PVC for launching mortars and stick to what the professionals use Cardboard, HDPE, Fiberglass, or Steel.