Schedule 40 Pipe Pressure Rating Chart and Guide

Schedule 40 pipe is one of the most widely used pipe specifications in industries such as oil & gas, water treatment, chemical processing, construction, fire protection, and general engineering. Whether you are selecting a carbon steel, stainless steel, or PVC pipe, understanding its pressure rating is essential for ensuring system safety, code compliance, and long-term reliability.

Many people mistakenly believe that every Schedule 40 pipe has the same pressure rating. In reality, the maximum allowable pressure depends on several factors, including pipe size, wall thickness, material strength, operating temperature, and the applicable design standard.

What Is Schedule 40 Pipe?

Schedule 40 (SCH 40) is a standardized pipe wall thickness designation defined by ASME B36.10M for carbon steel pipes and ASME B36.19M for stainless steel pipes. The word "Schedule" refers to the wall thickness of the pipe rather than its pressure rating.A Schedule 40 pipe with the same nominal pipe size (NPS) always has the same wall thickness, regardless of the manufacturer. However, the pressure rating varies because different materials have different allowable stresses.
For example:

Pipe Material	Pressure Capability
Carbon Steel	High
Stainless Steel	High
PVC	Moderate
Galvanized Steel	Similar to Carbon Steel

Related Guide: Schedule 40 Pipe Meaning

What Is the Maximum Pressure Rating of Schedule 40 Pipe?

The maximum pressure rating of a Schedule 40 pipe depends on its material, nominal size (NPS), wall thickness, and operating temperature. Under normal ambient conditions, small-diameter carbon steel Schedule 40 pipes can withstand several thousand psi, while larger pipes have significantly lower pressure ratings. PVC Schedule 40 pipes generally operate at much lower pressures than steel pipes.

The following pressure rating chart provides typical maximum allowable pressures for Schedule 40 pipes and serves as a practical reference for engineers, contractors, and purchasing professionals.

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.

Schedule 40 Pipes Pressure Rating Chart

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).

Schedule 40 Pipe Dimensions and Wall Thickness

Although Schedule 40 refers to a standardized wall thickness, the actual thickness varies according to the nominal pipe size (NPS).

NPS	OD (in.)	Typical Wall Thickness
1/2"	0.84	0.109
1"	1.315	0.133
2"	2.375	0.154
4"	4.5	0.237

Larger pipes maintain the Schedule designation but have different wall thicknesses to meet design standards.
For the complete dimensions, outside diameter (OD), inside diameter (ID), and wall thickness table:
Read: Sch 40 Pipe Dimensions

Common Materials and Sch 40 Pressure Ratings:

Carbon Steel Pipes (ASTM A53/A106): Carbon steel Sch 40 can withstand relatively high pressures at room temperature. For example, DN50 (2-inch) steel pipes can meet the working pressure requirements of common water systems. Specific details should be found in ASME standards.
PVC Pipes: PVC Sch 40 has a lower pressure rating and is suitable for industrial water supply and drainage, but is generally not suitable for high-pressure steam systems.

Comparison: Sch 40 is typically lower than the pressure ratings of Sch 80 (high pressure) and Sch 160 (high-pressure environment).

Carbon Steel
Carbon steel Schedule 40 pipe offers excellent mechanical strength and is widely used in industrial piping systems. Related Guide:Schedule 40 Carbon Steel Pipe

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.

FAQ: Schedule 40 Pipe Pressure Rating

What is the maximum PSI for Schedule 40 pipe?

For carbon steel pipes, the maximum pressure typically ranges from 1,000 to 3,000 psi under standard conditions, depending on the pipe diameter.

What pressure can a Schedule 40 pipe handle?

The pressure rating of a Schedule 40 pipe depends on its size, material, and temperature. Smaller carbon steel pipes can handle up to around 2,000 psi, while larger diameters are rated for lower pressure.

Is Schedule 40 pipe suitable for gas lines?

Yes, Schedule 40 pipe is widely used for low to medium-pressure gas applications, provided it complies with local codes and safety standards.

Does pipe size affect pressure rating?

Yes. As the pipe diameter increases, the pressure rating decreases because larger pipes experience greater internal stress.

Which is stronger, Schedule 40 or Schedule 80?

Schedule 80 pipe is stronger and has a higher pressure rating due to its thicker wall compared to Schedule 40.

Related Schedule 40 Resources

Schedule 40 Pipe Meaning

Sch 40 Pipe Dimensions

SCH 40 vs SCH 80

SCH 40 vs SCH 40S

Schedule 40 Stainless Steel Pipe

How to Calculate Schedule 40 SMLS Pipe Pressure Rating ?