 FACT: Fireworks mortar tubes must be at least Schedule 40 ABS tube,  not the lightweight Schedule 80 PVC tube shown. The lifting charge  would immediately explode through such a thin tube.  Fireworks are never launched without maintaining a visual reference  to the mortar racks (which incidentally are banned by law to be  placed on rolling trailers), allowing the pyrotechnician to  immediately cease launching if there was any damage or instability  to those racks.