Steel Pipe Nominal Size, Scheduling and Differences, Part 2

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Steel Pipe Nominal Size, Scheduling and Differences, Part 2

steel pipe nominal size scheduling

In part one of this two-part blog series, we went over some of the important designations for steel and metal pipe. Nominal pipe size and pipe schedule are vital measurement factors for both steel and other metal pipe types, helping define several important characteristics that play a role in which pipe you’ll choose.

At Wasatch Steel, we’re happy to offer a huge range of steel pipe along with steel sheet, steel tubing and many others. To really understand how pipe schedule and nominal pipe size play a role in differing pipe qualities, we ended part one of our series by looking at the differences between Schedule 40 and Schedule 80 pipe – today’s part two will dig into these differences a bit more specifically so you can get an idea of this realm.


First and foremost, there’s one area that sees absolutely no change between Schedule 40 and Schedule 80 pipe: Outside diameter. These two schedules both use the same fittings and the same points of entry on the exterior, meaning they’re interchangeable in this area.

Now, interior diameter is a different story. Schedule 40 will have a larger inside diameter than Schedule 80 pipe, all of which will trace back to the nominal pipe size.


The differences in these two types begin to appear when you get into weight. Schedule 40 pipe, to be particular, weighs significantly less per foot than Schedule 80 pipe, as you might expect based on material differences. This means Schedule 40 pipe tends to be easier to install, especially in long runs.

Cost Factors

Cost is always an important factor when it comes to steel or metal materials, and the general rule is simple: The greater quantity of materials used, the higher the cost. And because Schedule 80 pipe requires more material, it will be the costlier choice. Schedule 40 is ideal for situations where strength isn’t so important, as it can be purchased for a more affordable number.

Common Uses

As we just noted, stronger needs when it comes to steel or metal pipe will be filled by Schedule 80 pipe – there are some situations where inspectors may even require Schedule 80 pipe due to strength needs. For lower-strength requirements, however, Schedule 40 pipe is often used.


In any cases where an inspector designates a higher-schedule pipe for a given use or construction format, contractors on the project must follow this designation. They should never substitute lower-schedule pipe for any reason, as this will not stand up to strength needs and could pose major safety risks moving forward.

For more on nominal pipe size and pipe schedule, or to learn about any of our steel products or steel services, speak to the staff at Wasatch Steel today.