The tensile strength, 40 kg pressure, is indicated by the sch40 in the 12 sch 40 pipe pipe. It is denoted by a 4.0mm standard thickness. Sch 40 and sch 80 pipe are built of the same material as sch 80 pipe. The thickness of the pipe wall determines the difference in structure; the higher the schedule, the thicker the pipe wall.
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