Schedule 40 Carbon Steel Pipe: Thickness, Dimensions & Weight in mm

What is Schedule 40 Steel Pipe?

Schedule 40 (SCH 40) is the most commonly used standard wall thickness grade for carbon steel pipes, defined by ASME/ANSI B36.10. It offers a balanced combination of strength, weight, and cost-effectiveness, making it the default choice for a wide range of low to medium pressure applications. This guide provides complete dimensional data, weight calculations, and practical selection tips to help you specify SCH 40 pipes for your project.

SCH 40 covers almost all pipe sizes from NPS 1/8 to NPS 24. In common steel pipe wall thickness classes (such as Sch 5S, 10, 20, 40, 80, 160, XXS), the wall thickness increases with the Sch number. Sch 40 is thicker than Sch 10/20, with a higher pressure resistance; but thinner than Sch 80/160, with a lower pressure resistance. It strikes a good balance between mechanical strength, weight, and cost.

Size characteristics:

a. For all Sch 40 pipes, the outer diameter is fixed. For example, NPS 2 pipes, whether Sch 40 or Sch 80, have the same outer diameter of 60.3 mm (2.375 inches). This is specified by the standard.

b. Because the outer diameter is fixed, increasing the wall thickness will result in a smaller inner diameter. Therefore, the inner diameter of a Sch 40 pipe is smaller than that of a Sch 10 pipe, but larger than that of a Sch 80 pipe. The wall thickness of a Sch 80 pipe is always greater than that of a Sch 40 pipe of the same size.

Pipe Sch 40 Chart: Dimensions, Weight & Pipe Wall Thickness

The following is a reference table of nominal dimensions, outer diameter, wall thickness (mm), and weight data for SCH 40 carbon steel pipes, compiled according to ASME/ANSI B36.10 standard.

Nominal size [inches]	Outside diameter [inches]	Outside diameter [mm]	Wall thickness [inches]	Wall thickness [mm]	Weight [lb/ft]	Weight [kg/m]
1/8 DN6	0.405	10.3	0.068	1.73	0.24	0.37
1/4 DN8	0.540	13.7	0.088	2.24	0.42	0.84
1/2 DN10	0.840	21.3	0.109	2.77	0.85	1.27
3/4 DN20	1.050	26.7	0.113	2.87	1.13	1.69
1 DN25	1.315	33.4	0.133	3.38	1.68	2.50
1 1/4 DN32	1.660	42.2	0.140	3.56	2.27	3.39
1 1/2 DN40	1.900	48.3	0.145	3.68	2.72	4.05
2 DN50	2.375	60.3	0.154	3.91	3.65	5.44
2 1/2 DN65	2.875	73.0	0.203	5.16	5.79	8.63
3 DN80	3.500	88.9	0.216	5.49	7.58	11.29
3 1/2 DN90	4.000	101.6	0.226	5.74	9.11	13.57
4 DN100	4.500	114.3	0.237	6.02	10.79	16.07
5 DN125	5.563	141.3	0.258	6.55	14.62	21.77
6 DN150	6.625	168.3	0.280	7.11	18.97	28.26
8 DN200	8.625	219.1	0.322	8.18	28.55	42.55
10 DN250	10.750	273.0	0.365	9.27	40.48	60.31
12 DN300	12.750	323.8	0.406	10.31	53.52	79.73
14 DN350	14	355.6	0.375	11.13	54.57	94.55
16 DN400	16	406.4	0.500	12.70	82.77	123.30
18 DN450	18	457.2	0.562	14.27	104.67	155.80
20 DN500	20	508.0	0.594	15.09	123.11	183.42
24 DN600	24	610.0	0.688	17.48	171.29	255.41

Note: 

This dimensional table applies to both seamless and welded steel pipes (such as ASTM A53/A106).
The above data applies to carbon steel, alloy steel, and stainless steel pipes. The outer diameter (OD) is fixed; as the Schedule number (wall thickness series) increases, the wall thickness increases, and the inner diameter (ID) decreases accordingly.
Nominal vs. Actual: The outer diameter and wall thickness in the table are standard values. Actual manufactured pipes have permissible dimensional tolerances (e.g., wall thickness tolerance is approximately ±12.5%). For accurate strength calculations, the minimum measured wall thickness must be used.

Quick Reference for Common Sizes:

● 2 inch SCH 40 pipe thickness: 3.91 mm (OD: 60.3 mm)
● 4 inch SCH 40 pipe thickness: 6.02 mm (OD: 114.3 mm)
● 6 inch SCH 40 pipe thickness: 7.11 mm (OD: 168.3 mm)
● 8 inch SCH 40 pipe thickness: 8.18 mm (OD: 219.1 mm)
● 10 inch SCH 40 pipe thickness: 9.27 mm (OD: 273.0 mm)

For all other sizes, please refer to the complete chart above.

Common Uses & Selection Tips for Schedule 40 Pipe:

Understanding the common applications and key selection factors for SCH 40 pipe helps ensure you choose the right material and specifications for your project.

Common applications of Schedule 40 steel pipes:

1. Low-pressure fluid transportation
● Tap water, gas (ASTM A53 Sch 40 galvanized pipe).
● Chemical media (such as ASTM A106 Sch 40 seamless pipe).

2. Buildings and structures
● Scaffolding (but must comply with structural standards, such as EN 39).
● Air conditioning and ventilation ducts (thin-wall Sch 5/10 is more commonly used).

3. Machinery and equipment
● Low-pressure pipelines in hydraulic systems (high pressure requires Sch 80 or above).

● Food industry (stainless steel 304 Sch 40).

Key selection notes:

1. Pressure matching
Calculate the design pressure to ensure that the pressure bearing capacity of Sch 40 is sufficient (safety factor needs to be considered).

2. Material selection
Corrosive environment → Select stainless steel Sch 40 (ASTM A312) [View Stainless Steel SCH 40S Pipe Dimension Chart] or galvanized carbon steel (ASTM A53).
High temperature environment → Select ASTM A106 Sch 40 (temperature resistance ≤350℃).

3. Economic efficiency

Sch 40 is the most cost-effective general choice, but Sch 80/160 is required for ultra-high pressure scenarios.

Frequently Asked Questions (FAQ):

Q1. What is the thickness of Schedule 40 pipe?
The thickness of Schedule 40 pipe depends on its nominal size (NPS). Below are the wall thicknesses for the most commonly requested sizes:

● 2 inch SCH 40 pipe: 3.91 mm
● 4 inch SCH 40 pipe: 6.02 mm
● 6 inch SCH 40 pipe: 7.11 mm
● 8 inch SCH 40 pipe: 8.18 mm
● 10 inch SCH 40 pipe: 9.27 mm

For the complete list, please refer to the dimension chart above. Remember, for the same NPS, the outside diameter (OD) remains constant; only the wall thickness and inner diameter (ID) change.

Q2. How much does Schedule 40 pipe weigh?
The weight depends on the pipe's size, material, and length. You can calculate it using the formula:

Weight per meter (kg/m) = [OD (mm) - Wall Thickness (mm)] × Wall Thickness (mm) × 0.02466

For example, a 2" SCH 40 carbon steel pipe (OD: 60.3mm, wall: 3.91mm) weighs approximately:
(60.3 - 3.91) × 3.91 × 0.02466 ≈ 5.44 kg/m

Use the table above to find the weight for other sizes. For an exact quote, please provide your required size, material, and length.

Q3. What is the pressure rating of Schedule 40 pipe?
The pressure rating of Schedule 40 pipe varies, depending on size, material, and temperature. At room temperature, the pressure rating of carbon steel Schedule 40 pipe ranges from approximately 700 psi to 2,200 psi (4.8 to 15.2 MPa), with smaller diameter pipes offering higher pressure ratings. ▶ [Click here to learn more about the Pressure Rating Chart for Schedule 40 Steel Pipe].

Q4. Is Sch 40 a seamless pipe or a welded pipe?
Both!
● Seamless pipe: ASTM A106 Sch 40
● Welded pipe: ASTM A53 Sch 40

Q5. Can Schedule 40 pipe be threaded?
Yes, threading is completely possible on Schedule 40 pipe, and it's a very common and standard operation. Its moderate wall thickness provides the necessary material thickness for threading while ensuring strength after connection. However, for very large pipe sizes (e.g., 8 inches and above), butt welds or flange connections are generally recommended as threading can significantly weaken the pipe.

Q6. Where is Schedule 40 pipe used?
Due to its economical and versatile nature, Schedule 40 pipe is widely used in:

● Building water supply and drainage systems
● Low-pressure fluid transport (water, air, oil)
● Heating, ventilation, and air conditioning (HVAC) systems
● Structural support and scaffolding

Q7. SCH 40 vs. SCH 80: What are the differences?
The key difference is wall thickness. SCH 80 is typically 30% to 100% thicker than SCH 40 for the same pipe size, making it significantly stronger, heavier, and able to withstand higher pressures. For a full comparison table covering all sizes, weight, cost, and application guidelines, please see our dedicated guide:▶ [Schedule 40 vs. Schedule 80: A Selection Guide].

Need SCH 40 Carbon Steel Pipe for Your Project?

Hunan Standard Steel Co., Ltd (HSCO) is a trusted direct manufacturer, offering high-quality Sch 40 carbon steel pipe in sizes up to 24" with wall thicknesses up to 17.48mm. 

Get a Quick Quote or Technical Support:
△ Email us: sales@hu-steel.com (Please include your required size, grade, and quantity for priority handling)

Our experienced team will respond within 24 hours with detailed specifications and competitive pricing.

Read more: Schedule 80 Carbon Steel Pipe Thickness