Difference Between Schedule 40 and Schedule 80 Pipe

Attributes such as outside diameter, wall thickness, and inside diameter must be understood when working with metal pipes. However, many times pipe is not designated directly by those dimensions. Instead, a pipe is often referred to by its nominal pipe size and schedule number. Since references to pipe schedules are common in the industry, it is vital to understand how the pipe scheduling system works and the differences between Schedule 40 and Schedule 80, two of the most common types of pipe schedules.

What Does Nominal Pipe Size Mean?

Nominal pipe size (NPS) is an approximate measurement of the inside diameter of a pipe and acts as an identifier for different kinds of pipes. It is not an exact measurement but a reference number that can be used to determine the exact dimensions of the inner diameter of a pipe. However, this only applies to pipes 12” and under, for 14” and greater it is the outside diameter.

In the context of Schedule 40 pipes, NPS becomes especially relevant as it is commonly used to categorize and differentiate these pipes based on their nominal sizes. The designation “Schedule 40” refers to the pipe’s wall thickness and has a specific range of NPS values. For instance, Schedule 40 pipe dimensions encompass NPS values from 1/8 inch up to 36 inches. Despite the variation in wall thickness, the nominal pipe size remains consistent for Schedule 80 pipes, covering the same range of NPS values from 1/8 inch up to 36 inches.

What is a Pipe Schedule?

A pipe schedule (SCH) is not an actual measurement – it is a number based on a wall thickness formula. You can have several pipes with the same outside diameter, but with different schedule numbers – meaning that each schedule represents a different wall thickness. The best way to find these dimensions is to use a Pipe Schedule Chart for nominal pipe size and schedule number.

Combining the pipe schedule and nominal pipe size allows for easy identification and selection of pipes suitable for specific applications, considering factors like pressure requirements, flow rates, and structural integrity.

What is the Difference Between Schedule 40 vs. Schedule 80 Pipes?

The most significant difference between schedule 40 and schedule 80 pipe is the wall thickness, inside diameter, and weight. Of course, all these numbers will vary based on the nominal pipe size. There are also many other pipe schedule numbers as well. For these reasons, it is important to reference a pipe schedule table to ensure that the proper pipe size is selected.

Wall Thickness – Schedule 80 pipes have a thicker wall than Schedule 40 pipes for the same NPS. The increased wall thickness makes Schedule 80 pipes more robust and able to handle higher pressure and heavier loads.

Weight – Schedule 40 pipe weight depends on its length and material composition but is less than Schedule 80 pipe weight due to the thinner wall.

Pressure Rating – Due to its comparatively thinner wall, Schedule 40 pipe has a lower pressure rating than Schedule 80 pipe. Schedule 80 pipes can withstand higher pressure and are commonly used in heavy-duty applications.

Strength and Durability – While suitable for many general-purpose applications, Schedule 40 pipes may not handle extreme pressure or stress as effectively as Schedule 80 pipes. The increased wall thickness of Schedule 80 pipes provides greater strength and durability.

Both Schedule 40 and Schedule 80 pipes have their unique applications and strengths, and understanding their dimensions and weight enables professionals to select the right pipe for their specific needs. Visit Metal Supermarkets online or contact your closest metal supply store today and explore their diverse selection of Schedule 40 and Schedule 80 pipes cut to your exact specifications.