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What Is Schedule 40 Pipe? Thickness, Dimensions, Standards and Uses
Schedule 40 Pipe, commonly abbreviated as SCH 40 pipe, is a pipe with a standardized wall thickness associated with a particular Nominal Pipe Size (NPS). The number “40” does not represent a fixed wall thickness in millimetres. Instead, the actual wall thickness varies according to the nominal pipe size and applicable dimensional standard.
Schedule 40 pipe is available in different materials, including carbon steel, stainless steel, alloy steel, galvanized steel and PVC. It is widely used because it provides a practical balance between strength, internal flow area, cost and availability.
For example, a 4-inch Schedule 40 steel pipe has an outside diameter of approximately 114.30 mm and a wall thickness of approximately 6.02 mm. Its approximate internal diameter is 102.26 mm. The actual dimensions should always be confirmed against the applicable pipe dimensional standard and purchase specification.
What Is Schedule 40 Pipe?
40 Schedule Pipe, commonly abbreviated as SCH 40 pipe, is a pipe with a standardized wall thickness associated with a particular Nominal Pipe Size (NPS). The number “40” does not represent a fixed wall thickness in millimetres. Instead, the actual wall thickness varies according to the nominal pipe size and applicable dimensional standard.
Pipe Schedule 40 is available in different materials, including carbon steel, stainless steel, alloy steel, galvanized steel and PVC. It is widely used because it provides a practical balance between strength, internal flow area, cost and availability.
For example, a 4-inch Schedule 40 steel pipe has an outside diameter of approximately 114.30 mm and a wall thickness of approximately 6.02 mm. Its approximate internal diameter is 102.26 mm.
The actual dimensions should always be confirmed against the applicable pipe dimensional standard and purchase specification.
What Does SCH 40 Mean?
SCH 40 is an abbreviation for Schedule 40.
In pipe terminology, a schedule identifies the standardized wall thickness associated with a particular nominal pipe size. Therefore, Schedule 40 is a dimensional designation, not a material grade.
For the same nominal pipe size:
- Schedule 40 has a standard wall thickness.
- Schedule 80 generally has a thicker wall.
- A thicker wall normally results in a smaller internal diameter.
- Pipe weight generally increases as wall thickness increases.
For example, an ASTM A53 Grade B Schedule 40 pipe and an ASTM A312 TP316 Schedule 40S pipe are different products because their material specifications are different, even though both use a schedule-based dimensional designation.
Therefore, when ordering pipe, the material specification and schedule should be specified separately.
Schedule 40 Pipe Size Chart
40 Schedule Pipe is one of the most commonly used pipe schedules for industrial, commercial, plumbing and process piping applications. The Schedule 40 pipe size chart provides the nominal pipe size, DN, outside diameter, wall thickness and inside diameter for different pipe sizes.
Schedule 40 does not indicate one fixed wall thickness. The actual wall thickness varies according to the nominal pipe size. Therefore, the dimensions of a 1-inch Schedule 40 pipe are different from those of a 6-inch Schedule 40 pipe.
| NPS | DN | Outside Diameter (OD) | Wall Thickness | Inside Diameter (ID) |
|---|---|---|---|---|
| 1/8" | DN 6 | 10.3 mm | 1.73 mm | 6.84 mm |
| 1/4" | DN 8 | 13.7 mm | 2.24 mm | 9.22 mm |
| 3/8" | DN 10 | 17.1 mm | 2.31 mm | 12.48 mm |
| 1/2" | DN 15 | 21.3 mm | 2.77 mm | 15.76 mm |
| 3/4" | DN 20 | 26.7 mm | 2.87 mm | 20.96 mm |
| 1" | DN 25 | 33.4 mm | 3.38 mm | 26.64 mm |
| 1 1/4" | DN 32 | 42.2 mm | 3.56 mm | 35.08 mm |
| 1 1/2" | DN 40 | 48.3 mm | 3.68 mm | 40.94 mm |
| 2" | DN 50 | 60.3 mm | 3.91 mm | 52.48 mm |
| 2 1/2" | DN 65 | 73.0 mm | 5.16 mm | 62.68 mm |
| 3" | DN 80 | 88.9 mm | 5.49 mm | 77.92 mm |
| 4" | DN 100 | 114.3 mm | 6.02 mm | 102.26 mm |
| 5" | DN 125 | 141.3 mm | 6.55 mm | 128.20 mm |
| 6" | DN 150 | 168.3 mm | 7.11 mm | 154.08 mm |
| 8" | DN 200 | 219.1 mm | 8.18 mm | 202.74 mm |
| 10" | DN 250 | 273.1 mm | 9.27 mm | 254.56 mm |
| 12" | DN 300 | 323.9 mm | 9.53 mm | 304.84 mm |
Note: The dimensions shown above are commonly referenced Schedule 40 dimensions. Always verify the applicable dimensional standard, material specification, pipe tolerance and project requirements before procurement or fabrication.
Schedule 40 Pipe Thickness in mm
thickness of schedule 40 pipe depends on the nominal pipe size and the applicable dimensional standard. The following common dimensions are generally associated with ASME B36.10M for carbon and alloy steel pipe.
| NPS | NB / DN | Outside Diameter (OD) | 40 Schedule Pipe Thickness | Approx. Inside Diameter (ID) |
|---|---|---|---|---|
| ½ inch | 15 NB / DN 15 | 21.34 mm | 2.77 mm | 15.80 mm |
| 1 inch | 25 NB / DN 25 | 33.40 mm | 3.38 mm | 26.64 mm |
| 1½ inches | 40 NB / DN 40 | 48.30 mm | 3.68 mm | 40.94 mm |
| 2 inches | 50 NB / DN 50 | 60.33 mm | 3.91 mm | 52.51 mm |
| 2½ inches | 65 NB / DN 65 | 73.03 mm | 5.16 mm | 62.71 mm |
| 3 inches | 80 NB / DN 80 | 88.90 mm | 5.49 mm | 77.92 mm |
| 4 inches | 100 NB / DN 100 | 114.30 mm | 6.02 mm | 102.26 mm |
| 6 inches | 150 NB / DN 150 | 168.28 mm | 7.11 mm | 154.06 mm |
| 8 inches | 200 NB / DN 200 | 219.08 mm | 8.18 mm | 202.72 mm |
| 12 inches | 300 NB / DN 300 | 323.85 mm | 9.53 mm | 304.79 mm |
These are typical reference dimensions. Final dimensions, tolerances and mass should be confirmed against the applicable standard and purchase specification.
Does Schedule 40 Have the Same Thickness for Every Pipe Size?
No. Schedule 40 does not represent one fixed wall thickness. The wall thickness changes according to the nominal pipe size.
For example:
- ½-inch Schedule 40 steel pipe: approximately 2.77 mm wall thickness
- 2-inch Schedule 40 steel pipe: approximately 3.91 mm wall thickness
- 4-inch Schedule 40 steel pipe: approximately 6.02 mm wall thickness
- 12-inch Schedule 40 steel pipe: approximately 9.53 mm wall thickness
Schedule 40 Pipe Dimensions Chart
Schedule 40 Pipe Dimensions can include the nominal pipe size, NB or DN designation, outside diameter, wall thickness, inside diameter, weight per metre, length and end preparation.
- Nominal Pipe Size (NPS)
- NB or DN designation
- Outside Diameter (OD)
- Wall Thickness
- Inside Diameter (ID)
- Weight per metre
- End preparation
- Length
- Dimensional tolerances
It is important to understand that the nominal pipe size is not necessarily the actual outside diameter.
For example, a 2-inch Schedule 40 steel pipe has an outside diameter of approximately 60.33 mm, rather than 50.8 mm.
This is why pipe OD and ID charts should be used when selecting fittings, flanges and other connections.
Common NB to Inch Conversions
| NB / DN | Nominal Pipe Size |
|---|---|
| 15 NB / DN 15 | ½ inch |
| 25 NB / DN 25 | 1 inch |
| 40 NB / DN 40 | 1½ inches |
| 50 NB / DN 50 | 2 inches |
| 65 NB / DN 65 | 2½ inches |
| 80 NB / DN 80 | 3 inches |
| 125 NB / DN 125 | 5 inches |
| 150 NB / DN 150 | 6 inches |
| 200 NB / DN 200 | 8 inches |
NB, DN and NPS are nominal designations. They should not be confused with the actual pipe outside diameter.
Schedule 40 Pipe Standards
Seamless Schedule 40 Pipe is a dimensional designation, so the applicable standard depends on the pipe material and service.
ASME B36.10M
ASME B36.10M covers the dimensions and nominal weights of welded and seamless wrought steel pipes. It is commonly used for carbon steel and alloy steel pipe dimensions.
ASME B36.19M
ASME B36.19M covers dimensions for welded and seamless wrought stainless steel pipe. Stainless steel pipes are commonly identified using Schedule 40S and other stainless steel schedule designations.
Stainless steel pipe dimensions should therefore be checked against ASME B36.19M, because stainless steel pipe dimensions can differ from carbon steel dimensions for certain sizes.
Common ASTM Specifications
Schedule 40 pipes may be manufactured according to different ASTM specifications depending on material and application.
| ASTM Specification | Typical Application |
|---|---|
| ASTM A53 | Carbon steel pipe |
| ASTM A106 | Seamless carbon steel pipe for elevated-temperature service |
| ASTM A312 | Austenitic stainless steel pipe |
| ASTM A790 | Duplex stainless steel pipe |
| ASTM D1785 | PVC Schedule 40 pipe |
The important distinction is that Schedule 40 identifies the dimensional designation, while the ASTM specification establishes requirements related to the material, manufacturing, testing and performance of the pipe.
Schedule 40 Carbon Steel, Stainless Steel and PVC Pipe
Schedule 40 is used with different pipe materials. However, the applicable dimensions, pressure performance and temperature limits can differ between materials.
Schedule 40 Carbon Steel Pipe
Schedule 40 carbon steel pipe is commonly used for:
- Water systems
- Mechanical piping
- Compressed-air lines
- Structural applications
- General industrial piping
Common specifications include ASTM A53 and ASTM A106, depending on the required service conditions.
Schedule 40 Stainless Steel Pipe
Schedule 40 stainless steel pipe, commonly designated as Schedule 40S, provides corrosion resistance and is available in grades such as 304 and 316.
Common stainless steel grades include:
Stainless steel Schedule 40S dimensions should be checked against ASME B36.19M.
Schedule 40 PVC Pipe
Schedule 40 PVC pipe is commonly used for:
- Water distribution
- Irrigation
- Drainage
- Selected pressure applications
PVC Schedule 40 pipe has different dimensional, pressure and temperature characteristics from steel Schedule 40 pipe.
Schedule 40 Pipe Applications
Schedule 40 pipe is used across a wide range of residential, commercial and industrial applications.
Common applications include:
- Water supply and distribution
- Plumbing systems
- HVAC piping
- Fire protection systems
- Irrigation systems
- Compressed-air lines
- Drainage and utility systems
- Chemical and petrochemical plants
- Oil and gas facilities
- Power plant auxiliary piping
- Structural and fabrication projects
The correct pipe material and specification should be selected based on factors such as corrosion resistance, operating temperature, design pressure, fluid properties, welding requirements and applicable codes.
Schedule 40 Pipe Pressure Rating
There is no single pressure rating applicable to every Schedule 40 pipe.
The allowable pressure depends on several factors, including:
- Pipe material and grade
- Nominal pipe size
- Wall thickness
- Operating temperature
- Corrosion allowance
- Seamless or welded construction
- Joint efficiency
- Connection method
- Applicable piping code
Therefore, a Schedule 40 pipe pressure chart should be treated as a preliminary reference only. Final pressure suitability should be established through the applicable engineering calculations and design code.
Schedule 40 vs Schedule 80 Pipe
Schedule 40 vs Schedule 80 Pipe different wall-thickness designations for pipe of the same nominal size.
| Feature | Schedule 40 Pipe | Schedule 80 Pipe |
|---|---|---|
| Wall Thickness | Standard wall | Thicker wall |
| Internal Diameter | Usually larger | Usually smaller |
| Weight | Lower | Higher |
| Material Usage | Lower | Higher |
| Cost | Generally lower | Generally higher |
| Pressure Suitability | Suitable for many general services | Often selected for more demanding services |
| Handling | Easier to handle | Heavier to install |
Schedule 80 is not automatically suitable for every high-pressure application. Material, temperature, pressure, corrosion allowance, joining method and applicable design code must still be considered.
Frequently Asked Questions About Schedule 40 Pipe
Schedule 40 pipe is a pipe with a standardized wall thickness designation associated with a particular Nominal Pipe Size (NPS). The actual wall thickness varies according to the pipe size and applicable dimensional standard.
SCH 40 is an abbreviation for Schedule 40. It identifies a standardized pipe wall thickness designation for a given nominal pipe size. Schedule 40 is a dimensional designation and is not a material grade.
Schedule 40 pipe thickness depends on the nominal pipe size. For example, a 2-inch Schedule 40 steel pipe has an approximate wall thickness of 3.91 mm, while a 4-inch Schedule 40 pipe has an approximate wall thickness of 6.02 mm.
A standard 2-inch Schedule 40 steel pipe has an approximate wall thickness of 3.91 mm. Its outside diameter is approximately 60.33 mm.
The outside diameter of a standard 2-inch Schedule 40 steel pipe is approximately 60.33 mm (2.375 inches). The actual inside diameter depends on the wall thickness.
The inside diameter of Schedule 40 pipe depends on the outside diameter and wall thickness. It can be calculated using ID = OD − (2 × Wall Thickness). For example, a 2-inch Schedule 40 steel pipe has an approximate ID of 52.51 mm.
No. Schedule 40 does not represent one fixed wall thickness. The wall thickness changes according to the nominal pipe size. For example, ½-inch Schedule 40 pipe is approximately 2.77 mm thick, while 12-inch Schedule 40 pipe is approximately 9.53 mm thick.
ASME B36.10M is commonly used for the dimensions of carbon and alloy steel pipe. For stainless steel pipe, the applicable dimensional standard is generally ASME B36.19M.
Schedule 40 stainless steel pipe is corrosion-resistant pipe manufactured in stainless steel grades such as 304 and 316. Stainless steel pipe dimensions are generally covered by ASME B36.19M and may use the Schedule 40S designation.
Schedule 80 pipe generally has a thicker wall than Schedule 40 pipe of the same nominal size. As a result, Schedule 80 pipe generally has a smaller internal diameter and higher weight. The appropriate schedule depends on the required design conditions.
Schedule 40 pipe is commonly used for water supply, plumbing, HVAC, fire protection, compressed-air systems, industrial piping, structural applications and general utility services. The suitable material and specification depend on the application.
No. Schedule 40 is a dimensional designation, not a material specification. Schedule 40 pipe can be manufactured from carbon steel, stainless steel, alloy steel, PVC and other materials, depending on the applicable standard.
Conclusion
Schedule 40 pipe is a standardized dimensional designation associated with pipe wall thickness and nominal pipe size. The actual wall thickness, outside diameter, inside diameter and weight vary according to the selected pipe size, material and applicable dimensional standard.
When purchasing Schedule 40 pipe, specify the nominal size, material grade, manufacturing method, dimensional standard, length, end finish, testing requirements and applicable ASTM or ASME specification.
Kamal Steels supplies steel and stainless steel pipes in various sizes, grades and specifications for industrial and export requirements.