Pipe Schedules: What Do They Mean?

If you've ever shopped for PVC pipe or fittings, you've probably come across either Schedule 40 or Schedule 80 pipe and wondered what the difference was. Looking at the pipe, you'll likely notice that they're about the same size and differ in color; you may come to the conclusion that the pipe schedule is related to the color or some other chemical property of the pipe, but you're still unsure. Today we're going to clear up some common misconceptions about pipe schedules and how they impact a project you may be working on.

How pipe is measured

Before we can get into the differences between different schedules of pipe, we first have to understand how the pipe is sized and learn the jargon of the industry. In the plumbing industry, pipes of a certain size are referred to by their NPS, or nominal pipe size. The outside diameter for all pipes of the same NPS is the same, despite what their schedule may be. The inner diameter of a pipe will change across different schedules for the same NPS; the schedules are a measure of the pipe thickness. Using both the NPS and the schedule, we can fully designate what type of pipe we have. As an example, 2" Schedule 40 PVC pipe has an NPS of 2" and a schedule of 40.

Pipe Schedules: Explained

Now that we've explained what NPS and OD are, we can review what pipe schedules are and how they relate to your jobs. As we mentioned in passing in the last section, a pipe's schedule is a measure of the thickness of its walls. While the schedule does tell you about the thickness of the pipe, it is not uniform across pipe sizes; smaller diameter pipes and fittings will have a thinner wall than larger diameter pipes and fittings of the same schedule. Despite the varying thickness of different nominal pipe sizes across the same schedule, fittings and pipes do not have the same pressure rating, even within the same schedule. You can view the charts below to see the OD, NPS, wall thickness, and pressure rating for the Schedule 40 and Schedule 80 PVC carried by Drainage Connect

If you've got any questions about what do pipe schedules mean, leave them below. If you liked this article, please check out more of our content, including these great related blog posts below. As always, be sure to like and subscribe to us on Facebook, Instagram, Pinterest, or Twitter to keep apprised of the latest and greatest in drainage technology as well as get the latest exclusive deals! If you're making your first purchase, sign up for the newsletter to get a 1-time-use 5% off coupon!