Schedule 40 Pipe Pressure Rating Chart and Guide

You may have heard of Schedule 40 pipe in your home improvement or engineering projects. It is actually one of the most common pipe specifications. To make your pipe system safe and efficient, it is important to know how much pressure it can withstand. This article will explain the pressure rating of Schedule 40 pipe in a simple and clear way, tell you how to determine the pressure strength, and provide detailed charts of various materials to help you easily choose the right pipe, whether you are an engineer, construction worker, or DIY enthusiast.

Schedule 40 pipes are widely used because they offer sufficient strength for many applications at a relatively affordable cost. They are manufactured in various materials, including carbon steel, stainless steel, PVC, and galvanized steel, each with distinct pressure handling capabilities.

Advanced Pressure Rating Calculations

Calculating pressure ratings requires the use of a modified Barlow formula that accounts for factors such as pipe wall thickness, outside diameter, allowable pressure, stresses, longitudinal joint quality, and wall thickness corrections. Calculating pressure ratings requires the use of a modified Barlow formula that accounts for factors such as pipe wall thickness, outside diameter, allowable pressure, stresses, longitudinal joint quality, and wall thickness corrections. Calculating pressure ratings requires the use of a modified Barlow formula that accounts for factors such as pipe wall thickness, outside diameter, allowable pressure, stresses, longitudinal joint quality, and wall thickness corrections. This advanced approach ensures a comprehensive understanding of the pressure capabilities of the pipeline.

Factors that affect pressure levels of Schedule 40 Pipe

The pressure rating of a pipe is the maximum internal pressure it can safely withstand at a given temperature without failure. Pressure ratings are influenced by:
Material Type: Different materials have different strength and temperature tolerances.
Wall Thickness: Thicker walls can handle higher pressure.
Pipe Diameter: Larger diameters usually reduce pressure capacity.
Operating Temperature: Higher temperatures generally decrease pressure ratings.
Manufacturing Standards: Compliance with API, ASTM, or ASME standards affects reliability.
Schedule 40 is a wall thickness designation, not a direct pressure rating. Therefore, pressure ratings for Schedule 40 pipes vary by material and size.

Schedule 40 Pipes Pressure Rating Chart

The following table presents the Maximum Allowable Pressure (also known as pressure rating) for Schedule 40 pipes across a range of nominal pipe sizes (NPS). The pressure values are shown in psi (pounds per square inch) and kPa (kilopascal), reflecting common units used globally.

Maximum Allowable Pressure (psi) (kPa)
NPS	Outside Diameter	Schedule
(inch)	(inch)	40
	(mm)
1/4 inch	0.54 inch	7985
	13.7 mm	55057
3/8 inch	0.675 inch	6606
	17.1 mm	45548
1/2 inch	0.84 inch	6358
	21.3 mm	43838
3/4 inch	1.05 inch	5273
	26.7 mm	36357
1 inch	1.315 inch	4956
	33.4 mm	34172
1 1/4 inch	1.66 inch	4133
	42.2 mm	28497
1 1/2 inch	1.9 inch	3739
	48.3 mm	25780
2 inch	2.375 inch	3177
	60.3 mm	21905
2 1/2 inch	2.875 inch	3460
	73 mm	23857
3 inch	3.5 inch	3024
	88.9 mm	20850
3 1/2 inch	4 inch	2769
	102 mm	19092
4 inch	4.5 inch	2581
	114 mm	17796
5 inch	5.563 inch	2273
	141 mm	15672
6 inch	6.625 inch	2071
	168 mm	14280
8 inch	8.625 inch	1829
	219 mm	12611
10 inch	10.75 inch	1664
	273 mm	11473
12 inch	12.75 inch	1560
	324 mm	10756
14 inch	14 inch	1533
	356 mm	10570
16 inch	16 inch	1531
	406 mm	10556
18 inch	18 inch	1530
	457 mm	10549
20 inch	20 inch	1455
	508 mm	10032
22 inch	22 inch
	559 mm
24 inch	24 inch	1405
	610 mm	9687
30 inch	30 inch
	762 mm
32 inch	32 inch	1054
	813 mm	7267
34 inch	34 inch	992
	864 mm	6840
36 inch	36 inch	1021
	914 mm	7040
42 inch	42 inch	875
	1067 mm	6033

1 in (inch) = 25.4 mm
1 psi (lb/in2) = 6,894.8 Pa (N/m2) = 6.895x10-2 bar

How to Calculate Pressure Rating for Schedule 40 Pipes?

The pressure rating can be estimated using the Barlow's formula:

Where:

• $P$ = Maximum allowable pressure (psi)

• S= Material allowable stress (psi)

• $t$ = Wall thickness (inch)

• $D$ = Outside diameter (inch)

This formula shows why thicker pipes and stronger materials have higher pressure ratings.

PVC Schedule 40 Pipes

PVC pipes are lightweight and resistant to corrosion, commonly used in residential and commercial plumbing. Pressure ratings at 73°F (23°C) are as follows:

Note: PVC pressure ratings decrease with increasing temperature. For instance, at 110°F (43°C), the pressure rating may reduce to approximately 51% of its value at 73°F (23°C).

Conclusion

Understanding the pressure ratings of Schedule 40 pipes across different materials is essential for selecting the appropriate piping for your application. Always consider factors such as operating temperature, material properties, and applicable standards. For high-pressure or high-temperature applications, materials like carbon steel or stainless steel may be more suitable, while PVC is ideal for lower-pressure, corrosion-resistant needs.