Whether you're new to the tube or alloy pipe industry or have been in the business for years, the term "Schedule 40" is not new to you. It's not just a simple term, it's a key metric, so let's dig a little deeper and find out why Schedule 40 is so popular!
What is Schedule 40
A Schedule 40 pipe is a pipe with a specific wall thickness. The specific wall thickness will vary depending on the outer diameter of the pipe. This is because the number after Schedule does not directly refer to a specific wall thickness, but rather is a categorization.
The formula for calculating the Schedule number is a simplified way to estimate the relationship between the wall thickness of a pipe and the pressure it is subjected to.
The formula is as follows:
Schedule Number = 1000 (P/S)
P represents the design working pressure of the pipe, usually in psi (pounds per square inch)
S represents the minimum allowable stress of the pipe material at operating temperature, also in psi (pounds per square inch).
This formula provides a theoretical framework for understanding the relationship between the thickness of pipes with different Schedule values and the maximum pressure they can safely withstand. In practice, the Schedule value of a pipe is predefined in the standard.
Schedule 40:Customary Units
| NPS | Outside Diameter (in) | inside diameter (in) | Wall Thickness (in) | Plain End Weight (lb/ft) | Identification |
| 1/8 | 0.405" | 0.269" | 0.068" | 0.24" | STD |
| 1/4 | 0.540" | 0.364" | 0.088" | 0.43" | STD |
| 3/8 | 0.675" | 0.493" | 0.091" | 0.57" | STD |
| 1/2 | 0.840" | 0.622" | 0.109" | 0.85 | STD |
| 3/4 | 1.050" | 0.824" | 0.113" | 1.13" | STD |
| 1 | 1.315" | 1.049" | 0.133 | 1.68" | STD |
| 1 1/4 | 1.660" | 1.380" | 0.140" | 2.27" | STD |
| 1 1/2 | 1.900" | 1.610" | 0.145" | 2.72" | STD |
| 2 | 2.375" | 2.067" | 0.154" | 3.66" | STD |
| 2 1/2 | 2.875" | 2.469" | 0.203" | 5.8 | STD |
| 3 | 3.500" | 3.068" | 0.216" | 7.58 | STD |
| 3 1/2 | 4.000" | 3.548" | 0.226" | 9.12" | STD |
| 4 | 4.500" | 4.026" | 0.237" | 10.8 | STD |
| 5 | 5.563" | 5.047" | 0.258" | 14.63 | STD |
| 6 | 6.625" | 6.065" | 0.280" | 18.99 | STD |
| 8 | 8.625" | 7.981" | 0.322" | 28.58 | STD |
| 10 | 10.750" | 10.020" | 0.365" | 40.52" | STD |
| 12 | 12.750" | 11.938" | 0.406" | 53.57" | —— |
| 14 | 14.000" | 13.124" | 0.438" | 63.50" | —— |
| 16 | 16.000" | 15.000" | 0.500" | 82.85" | XS |
| 18 | 18.000" | 16.876" | 0.562" | 104.76" | —— |
| 20 | 20.000" | 18.812" | 0.594" | 123.23" | —— |
| 24 | 24.000" | 22.624" | 0.688" | 171.45" | —— |
| 32 | 32.000" | 30.624" | 0.688" | 230.29" | —— |
| 34 | 34.000" | 32.624" | 0.688" | 245.00" | —— |
| 36 | 36.000" | 34.500" | 0.750" | 282.62" | —— |
Schedule 40:SI Units
| NPS | DN | Outside Diameter （mm） |
inside diameter (mm) |
Wall Thickness （mm） |
Plain End Mass (kg/m) |
Identification |
| 1/8 | 6 (3) | 10.3 | 6.84 | 1.73 | 0.37 | STD |
| 1/4 | 8(3) | 13.7 | 9.22 | 2.24 | 0.63 | STD |
| 3/8 | 10 | 17.1 | 12.48 | 2.31 | 0.84 | STD |
| 1/2 | 15 | 21.3 | 15.76 | 2.77 | 1.27 | STD |
| 3/4 | 20 | 26.7 | 20.96 | 2.87 | 1.69 | STD |
| 1 | 25 | 33.4 | 26.64 | 3.38 | 2.50 | STD |
| 1 1/4 | 32 | 42.2 | 35.08 | 3.56 | 3.39 | STD |
| 1 1/2 | 40 | 48.3 | 40.94 | 3.68 | 4.05 | STD |
| 2 | 50 | 60.3 | 52.48 | 3.91 | 5.44 | STD |
| 2 1/2 | 65 | 73.0 | 62.68 | 5.16 | 8.63 | STD |
| 3 | 80 | 88.9 | 77.92 | 5.49 | 11.29 | STD |
| 3 1/2 | 90 | 101.6 | 90.12 | 5.74 | 13.57 | STD |
| 4 | 100 | 114.3 | 102.26 | 6.02 | 16.08 | STD |
| 5 | 125 | 141.3 | 128.2 | 6.55 | 21.77 | STD |
| 6 | 150 | 168.3 | 154.08 | 7.11 | 28.26 | STD |
| 8 | 200 | 219.1 | 202.74 | 8.18 | 42.55 | STD |
| 10 | 250 | 273.0 | 254.46 | 9.27 | 60.29 | STD |
| 12 | 300 | 323.8 | 303.18 | 10.31 | 79.71 | —— |
| 14 | 350 | 355.6 | 333.34 | 11.13 | 94.55 | —— |
| 16 | 400 | 406.4 | 381 | 12.70 | 123.31 | XS |
| 18 | 450 | 457 | 428.46 | 14.27 | 155.81 | —— |
| 20 | 500 | 508 | 477.82 | 15.09 | 183.43 | —— |
| 24 | 600 | 610 | 575.04 | 17.48 | 255.43 | —— |
| 32 | 800 | 813 | 778.04 | 17.48 | 342.94 | —— |
| 34 | 850 | 864 | 829.04 | 17.48 | 364.92 | —— |
| 36 | 900 | 914 | 875.9 | 19.05 | 420.45 | —— |
Implementing Standards for Schedule 40
ASME B36.10M
Provides a detailed specification for Schedule 40 carbon steel pipe covering the dimensions, wall thicknesses, and weights of seamless and welded carbon and alloy steel pipe.
ASME B36.19M
Standard specifically for the dimensions, wall thicknesses, and weights of stainless steel seamless and welded steel pipe and tubes.
ASTM D1785
Schedule 40 PVC pipe typically follows this standard.
ASTM D3035 and ASTM F714
Specify size, wall thickness, and performance requirements for high-density polyethylene (HDPE) pipe.
API 5L
For line pipes for the transportation of natural gas, water, and oil, this standard establishes requirements and specifications for the manufacture of steel pipes.
AWWA C900
Standard for polyvinyl chloride (PVC) pressure pipe and fittings for water supply.
schedule 40 material types
Schedule 40 pipe can be manufactured from a variety of materials, including but not limited to:
Carbon Steel
Primarily used for the transportation of water and gas streams at low to moderate pressures. Examples include natural gas and oil transportation and water supply systems.
Stainless steel
Suitable for the handling and transportation of corrosive materials, hot water systems, and certain industrial processes that require high temperatures.
PVC (Polyvinyl Chloride)
Commonly used in cold water supply and drainage systems in residential and commercial buildings.
HDPE (High-Density Polyethylene)
Mainly for municipal water supply and sewage treatment and drainage systems.
Why Schedule 40 is widely used
Medium Wall Thickness
Schedule 40 pipes offer a medium wall thickness, which makes them strong enough to handle most low to medium-pressure applications while avoiding the unnecessary costs associated with thick walls.
Lower Price
Compared to thicker-walled pipes such as Schedule 80, Schedule 40 pipes offer lower material costs in many applications while still meeting strength and durability requirements.
Wide Range of Applications
Schedule 40 piping is suitable for use in a variety of fluid transfer systems, including water supply, drainage, heating, ventilation and air conditioning (HVAC), natural gas transmission, and more, making it a popular choice for residential, commercial, and industrial projects.
Easy to Work With and Install
Medium wall thicknesses make Schedule 40 pipe relatively easy to handle during cutting, welding, and installation, facilitating construction.
Durability
Schedule 40 piping offers excellent mechanical protection and corrosion resistance due to its moderate wall thickness, enabling long-term operation in a variety of environments.
Compliance with Standards
Schedule 40 piping follows internationally recognized standards such as the American Society for Testing and Materials (ASTM) and the American Society of Mechanical Engineers (ASME) to ensure its quality and performance.
Ease of Procurement
Due to its widespread use, Schedule 40 piping is highly available in the market and is easily purchased in a variety of sizes and materials.
An in-depth analysis of Schedule 40 pipes shows that they offer an ideal balance in terms of cost, strength, durability, and application flexibility. This not only makes it an indispensable part of a wide range of projects. As technology advances and standards are constantly updated, Schedule 40 pipes will undoubtedly continue to be widely used around the world to support more infrastructure construction and industrial development.
Post time: Feb-29-2024