What is schedule 40?

In simple terms, it fixes the wall size of a pipe. The nominal diameters of schedule 40 and schedule 80 pipe are the same and the fittings are the same. Schedule 80 is stronger than schedule 40.

Mechanical properties are material dependent. PVC, Stainless, Iron etc.

Here is a table for schedule 40 and 80 PVC. Harvel PVC Pipe Schedule 40 & 80 Dimensions—Harvel Plastics, Inc.

Schedule 40 is a rating that is used when referencing the thickness or wall of the PVC pipe Schedule 80 and Schedule 40 are the two most common, however there is also Schedule 120. As the Schedule increases, the pipe wall thickness increases. This adds additional strength to the PVC pipe, and it can take a lot more pressure.

Here is a chart that shows the differences in thickness of Schedule 40 Wall and Schedule 80 Wall:

https://formufit.com/pages/pvc-pipe-...mensions-chart

Please look at the posting dates before responding to a thread. This question was asked in Oct 2008, over eight years ago...

Although an old post, would like to add, as mentioned, the outer diameter is the same. Schedule 80 being Thicker, the inside diameter is Smaller. May need to increase size of conduit? It will change Wire fill.