A pipe's tensile strength refers to its ability to resist the effects of water hammer and internal hydrostatic pressure. Ductile iron pipe offers a 60,000 psi (pound per square inch) minimal tensile strength and PVC pipe offers 7,000 psi minimal tensile strength.
Burst pressure measures a pipe's resistance level to hydrostatic water pressure. The minimal burst pressure rating for ductile iron piping that is 6 inches in diameter is 350 psi and 200 psi for 24-inch ductile iron piping. Minimal burst pressure for 6-inch PVC pipe is 150 psi and 165 psi for 24-inch PVC pipe.
Crushing load refers to a pipe's ability to withstand loads that are applied externally. The Ductile Iron Pipe Research Institute tests and measures pipe-crushing loads. Six-inch ductile iron pipe offers 4,843 psi crushing-load resistance, while 6-inch PVC pipe offers 361 psi crushing-load resistance.