Yes they can. Since PVC conduit products have very long useful lives, not much pipe is currently available for recycling as it is still in use. While current standards do not generally allow for the practice of recycling used pipes into new certified pipes. PVC conduit producers can recycle nearly all production scrap in-house. Since PVC is a thermoplastic PVC conduit can simply be reground, pulverized and returned to the extrusion process to make new conduit.
PVC conduit, while combustible, does not continue to burn once a flame source is removed. A main cause of fire fatalities is exposure to carbon monoxide, which is produced from common materials and products like wood, furniture, carpet and fabrics. It is estimated that plastic conduit systems represent less than 1% of the mass of all combustible products in a building.
If the joint is over assembled, in other words, the spigot is jammed into the neck of the bell, the flexibility of the joint is lost. Uneven settlement in the trench may cause an over assembled joint to leak – do not assemble beyond the reference mark. Proper assembly calls for insertion of the spigot end into the bell so that it is in contact with the gasket. Keep the pipe lengths in proper alignment. Brace the bell while the spigot end is pushed under the gasket, so that previously completed joints will not be further inserted. Push the spigot into the bell until the assembly mark on the pipe barrel is flush with the end of the bell. Stabbing is not recommended and should be avoided.