Quote:
Originally Posted by CalcTeacher
where did the phrase "Schedule 40" come from?
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Whenever anything was designed (I'm talking in the old days, like early 20th century), the draftsman (draftsMAN, because women didn't do work like that,
) would draw the diagram of how the object would look, and then would provide a "schedule" or a list of specifications...the schedule could include size, tolerances, type of material, color, whatever else was called for by the engineer. In the case of pipe, there isn't much to specify...just diameter and thickness. So, "schedule" in pipe just means thickness