Schedule 40 pipe has thinner walls, so it is best for applications involving relatively low water pressure. Schedule 80 pipe has thicker walls and is able to withstand higher PSI (pounds per square inch). This makes it ideal for industrial and chemical applications.

What Does Nominal Pipe Size Mean?

The nominal pipe size is a rough external pipe diameter measurement. It is not a precise measurement, but rather a reference number, to identify the actual measurements of a pipe’s outside diameter. For example, a nominal tube of 3 refers to a pipe having an actual outside diameter of 3,500 inches.

What is Pipe Schedule?

An inner diameter and wall thickness for nominal pipe sizes are indicated by a pipe schedule. A schedule number has little meaning without knowing the nominal pipe size, except that higher schedule numbers will have thicker pipe walls if the nominal pipe size is kept constant. However, the precise wall thickness, diameter inside, and dimension outside diameter of a pipe may be calculated if nominal pipe size and schedule number are known. A pipe scheduling chart for nominal tube size and schedule numbers can best be used to identify such dimensions.

Why is it called schedule 40 pipe?

The pipe numbers are non-dimensional. In other words, SCH 40 doesn’t mean the pipe is 40 millimeters or 40 inches in diameter.

The parameters for each schedule are determined by the ASME B36.10M, which is the standard governing seamless and welded steel pipe dimensions. ASME B36.10M determines the numbers that designate each size.

Grades of Schedule 40 Steel Pipe

schedule 40 threaded end galvanized steel pipe

Most schedule 40 steel pipe is made from mild steel. This means it has a carbon content of about 0.2% to 0.25%. That’s very, very low, making the alloy mostly ferrous in composition.

To improve SCH 40 steel pipe’s corrosion resistance, steel manufacturers usually galvanize the steel, which means to plate it with a layer of zinc. If this option is not appropriate, schedule 40 pipe does come in stainless steel.

A53 steel pipe is the grade most commonly associated with SCH 40 steel pipe, but you can also find this schedule in other grades.

Schedule 40 Steel Pipe Dimensions

Thicknesses are measured by both wall thickness and outside diameter. As an example, a 1/8th-inch nominal size schedule 40 pipe has an outside diameter of 0.405 and a wall thickness of 0.068. Its weight per foot stands at 0.245.

A more common pipe is the 4-inch schedule 40 steel pipe. This pipe’s outside diameter is 4.5 with a wall thickness of 0.237 and a weight per foot of 10.79.

What size is schedule 40 steel pipe?

This steel pipe product comes in a variety of dimensions. The size of the pipe, its nominal diameter, actual inside diameter, and actual outside diameter all fit within the right parameters.

For example, a schedule 40 pipe that’s 2.5 inches in diameter will be 2.469 in actual inside diameter and 2.875 in actual outside diameter.

At Kloeckner, we can supply or cut schedule 40 steel pipes in nearly any length you need.

The Weight of Schedule 40 Steel Pipe

As a general rule, the weight per foot stands around 1.68 lbs.

How much weight can schedule 40 steel pipe hold?
How much weight it can hold depends on a variety of factors. If you buy a standard pipe — A53-grade, black steel — it will demonstrate 30,000 psi yield strength.

Chemical Composition of Schedule 40 Steel Pipe

Schedule 40 pipe refers to the nominal wall thickness, not the grade. Therefore, the chemical composition of a pipe schedule is not necessarily uniform.

However, schedule 40 pipe is made from low-carbon steel, usually grade A53 steel pipe. Its chemical composition also varies across types and welds, but as a point of reference, type S seamless weld A53 steel looks something like this:

Carbon – 0.25% (max)
Manganese – 0.95% (max)
Phosphorous – 0.05% (max)
Sulfur – 0.045% (max)
Copper – 0.4% (max)
Nickel – 0.4% (max)
Chromium – 0.4% (max)
Molybdenum – 0.15% (max)
Vanadium – 0.08% (max)

Difference Between Schedule 40 and Schedule 80 Pipe

Schedule 40 and schedule 80 pipes are very similar. They are so much alike, in fact, that some people conflate the two.

In truth, however, schedule 40 pipe has thinner walls than schedule 80. Consequently, schedule 80 can handle higher pressures than schedule 40, so it’s generally used for commercial applications.

How to know if schedule 40 pipe can handle the pressure

A mathematical formula can help you determine if schedule 40 or schedule 80 is right for your project.

SCH = (1,000)*(P/S)

In this equation, P equals the pipe’s internal working pressure, and S stands for how much stress the material can endure.

As an example, if your pipe has an internal working pressure of 450 psi and an S value of 12,000, then your equation would look like this:

(1,000) *(450/12,000) = 37.5

37.5 is very close to SCH 40 so you should be safe choosing that schedule.

Industries That Use Sch 40 Steel Pipe

Many industries use SCH 40 steel pipe, especially industries that need to supply air, gas, and water at high temperatures. This schedule pipe also sees a lot of use in construction work where its diameter, strength, and reactivity make it a reliable choice.

Applications of Sch 40 Steel Pipe

Most hardware stores sell schedule 40 steel pipes. Many DIYers enjoy using this product in creative projects. Schedule 40 steel pipe makes sturdy and attractive curtain rods, shelves, coat hooks, floor lamps, and magazine racks.

Of course, schedule 40 pipe’s primary application is transporting high-temperature, high-pressure liquids for commercial and residential properties in the oil and gas industry.

Schedule 40 Steel Pipe Prices

Schedule 40 steel pipe prices vary tremendously and depend on factors such as length, grade, and volume at purchase. If you buy a high volume of pipe directly from a company that offers quality fabrication services, such as Kloeckner Metals, your costs will run much lower than if you went to Home Depot for the same product.

To learn more about other kinds of steel pipe, steel tube, and steel plate products, take a look through our library of articles or contact us directly.