Schedule 40 Seamless Pipe Dimensions, Wall Thickness and Pressure Rating

Schedule 40 seamless pipe is one of the most widely used seamless steel pipe specifications in industrial piping systems.

This page includes SCH 40 pipe dimensions, wall thickness data, pressure ratings, and common material grades used in carbon steel seamless pipe applications.

1. What Is Schedule 40 Seamless Pipe

Schedule 40 seamless pipe is a seamless steel pipe manufactured with a wall thickness designated as SCH 40 under ASME B36.10M.

"Seamless" refers to pipe produced without a longitudinal weld seam. "Schedule" indicates the pipe wall thickness series, while "SCH 40" represents one of the most commonly used standard wall thickness classifications.

SCH 40 is commonly used for water transmission, oil and gas pipelines, process piping, fire protection systems, and general industrial service.

2. Schedule 40 Pipe Dimensions Chart

The following SCH 40 pipe dimensions chart shows outside diameter (OD), wall thickness (WT), inside diameter (ID), and weight according to ASME B36.10M.

SCH 40 Pipe Dimensions Chart

Note: For Schedule 40 pipe, the outside diameter is fixed for each NPS size. Changes in wall thickness directly affect the inside diameter, weight, and pressure capacity of the pipe.

3. Schedule 40 Pipe Wall Thickness

SCH 40 is a wall thickness series, and the actual thickness varies according to the nominal pipe size (NPS).

Common SCH 40 Pipe Wall Thickness

For the full SCH 40 wall thickness chart, refer to the dimensions table above.

4. Schedule 40 Pipe Sizes

Schedule 40 pipe is available in a wide range of nominal pipe sizes (NPS), from small-diameter instrumentation piping to large industrial transmission systems.

Common SCH 40 Pipe Sizes

For seamless steel pipe, NPS 2", 4", 6", and 8" are among the most widely used Schedule 40 sizes for industrial piping, water transmission, oil and gas systems, and structural applications.

Larger sizes such as NPS 14" to 32" are also available for pipeline and infrastructure projects.

5. Schedule 40 Pipe Pressure Rating

The pressure capacity of SCH 40 pipe depends on pipe size, material grade, operating temperature, and design code requirements.

Under identical conditions, smaller pipe sizes generally provide higher pressure ratings than larger sizes.

For detailed pressure calculations, material properties, and carbon steel grade data, see SCH 40 Carbon Steel Pipe page.

6. Common Materials for SCH 40 Seamless Pipe

The most commonly specified grades for SCH 40 seamless pipe are ASTM A106 Gr.B, ASTM A53 Gr.B, and API 5L Gr.B. API 5L Gr.B is primarily used in oil and gas transmission projects.

7. Applications of Schedule 40 Seamless Pipe

SCH 40 seamless pipe is commonly used in applications requiring moderate pressure capacity and reliable mechanical performance.

Typical applications include:

1) Water transmission systems

2) Oil and gas pipelines

3) Steam and process piping

4) Fire protection systems

5) Compressed air systems

6) Structural applications

7) Chemical and petrochemical facilities

8) Power generation plants

8. Schedule 40 vs Schedule 80

Schedule 40 and Schedule 80 pipes have the same outside diameter for a given NPS size. The primary difference is wall thickness.

SCH 40 is typically selected for general industrial service, while SCH 80 is used where higher pressure resistance is required. For a detailed comparison, see SCH 40 vs SCH 80 Pipe.

9. FAQs

Q1. What is SCH 40 pipe?

SCH 40 (Schedule 40) is a pipe wall thickness designation defined by ASME B36.10M. The actual wall thickness varies by nominal pipe size (NPS).

Q2. How thick is Schedule 40 pipe?

Schedule 40 pipe does not have a fixed thickness. For example, 1" SCH 40 pipe has a wall thickness of 3.38 mm, while 6" SCH 40 pipe has a wall thickness of 7.11 mm.

Q3. What is the wall thickness of Schedule 40 pipe?

The wall thickness depends on pipe size. A 2" SCH 40 pipe has a wall thickness of 3.91 mm, while a 12" SCH 40 pipe has a wall thickness of 10.31 mm.

Q4. Is Schedule 40 pipe the same as STD pipe?

For NPS 1/8" to 10", Schedule 40 is generally equivalent to STD (Standard Weight) pipe. For larger sizes, differences may exist.

Q5.What sizes are available in Schedule 40 pipe?

Schedule 40 pipe is commonly available from NPS 1/8" to NPS 36", including popular sizes such as 1", 2", 4", 6", 8", 10", and 12".

Q6.What is the pressure rating of Schedule 40 pipe?

The pressure rating depends on pipe size, material grade, and operating temperature. Under the same conditions, smaller SCH 40 pipes generally have higher pressure ratings than larger sizes.

Read more: Schedule 80 seamless steel pipe 
Seamless Steel Pipe Size Chart – OD, Wall Thickness

DIN EN 10220 – Steel Pipe Dimensions