Seamless steel pipe schedule 40

SCH 40 (Schedule 40) is a steel pipe wall thickness grade defined according to ASME B36.10M standard, belonging to the standard wall thickness (STD). It does not represent a specific number of millimeters; the actual wall thickness will vary with the nominal pipe diameter (NPS). SCH 40 seamless steel pipes are widely used in industrial piping systems due to their good balance between strength, pressure resistance, and cost.

What is a seamless steel pipe?

A seamless steel pipe is a type of steel pipe manufactured through processes such as heating, piercing, rolling, and cooling of a billet. Compared to welded steel pipes, seamless steel pipes have significant advantages in appearance and performance.

Firstly, its surface is smooth, without weld joints, resulting in better aesthetics. Secondly, seamless steel pipes exhibit superior strength and pressure resistance, capable of withstanding higher pressures and temperatures. This makes them widely used in specialized industries such as petroleum, chemical, and natural gas.

What is Schedule 40?

SCH40 refers to a specification designation for seamless steel pipes, representing the wall thickness. Specifically, Sch40 indicates a seamless steel pipe with a wall thickness of 40S, where "S" represents the standard wall thickness series.

Standards for Schedule 40 steel pipe:

ASME B36.10M: Seamless and welded steel pipes of carbon and alloy steel

ASME B36.19M: Stainless steel pipes (corresponding to 40S)

Schedule 40 pipes have relatively thick walls and are typically used in applications requiring high pressure and temperature. This specification of seamless steel pipe is widely used in the petroleum, chemical, shipbuilding, and heating industries.

Features of SCH40 seamless steel pipe

1. High strength

Schedule 40 steel pipes have relatively thick walls, enabling them to withstand high pressure and mechanical loads.

2. Strong corrosion resistance

Seamless steel pipes are typically made of high-quality steel and can operate stably for extended periods in harsh environments.

3. High dimensional accuracy

The manufacturing process of SCH40 seamless steel pipes is highly precise, resulting in high dimensional accuracy, making them suitable for applications with strict dimensional requirements.

4. Wide applications

SCH40 seamless steel pipes are widely used in the petroleum, chemical, heating, and shipbuilding industries for transporting various media, including liquids, gases, and solids. Common materials include: ASTM A106 Gr.B, ASTM A53 Gr.B, API 5L Gr.B / X42 / X52, ASTM A333 Gr.6 (low temperature).

SCH40 pipe dimensions

SCH40 pipe chart gives dimensions of steel pipes schedule 40. The chart includes sizes in inches and in millimeters.

Chemical composition of SCH 40 seamless steel pipe

The chemical composition of SCH 40 seamless steel pipe is specified in various standards and specifications. Depending on the regulations of the manufacturing unit and the country/region, the chemical composition of SCH 40 seamless steel pipe typically includes the following main components:

1. Carbon (C)

Approximately 0.3% to 0.5% of the seamless steel pipe's weight.

2. Manganese (Mn)

This component helps improve the toughness and hardness of the steel pipe, with a content typically between 0.6% and 1.65%.

3. Silicon (Si)

This component helps improve the corrosion resistance of the steel pipe, with a content typically between 0.25% and 0.6%.

4. Phosphorus (P) and Sulfur (S)

These components contribute to the formation of the steel pipe's crystal structure, and their content is typically low, approximately 0.05% for each.

5. Iron (Fe)

The main component of seamless steel pipe, with a content of 98.5% to 99.2%.

Mechanical properties of SCH40 seamless steel pipe

1. Tensile strength

The tensile strength of SCH40 seamless steel pipe is approximately 414 MPa.

This is the indicator used to evaluate the tensile strength of SCH40 seamless steel pipe.

2. Elongation

The elongation of SCH40 seamless steel pipe is approximately 25%.

This indicator is used to evaluate the ability of SCH40 seamless steel pipe to withstand tensile deformation.

3. Stiffness

The hardness of SCH40 seamless steel pipe is measured by Brinell hardness (HB) or Rockwell hardness (HR).

The hardness of SCH40 seamless steel pipe is typically in the range of 80–90 HB or 70–80 HR.

4. Impact resistance

The impact resistance of SCH40 seamless steel pipe depends on several factors, including wall thickness, impact velocity, and impact direction.

The impact resistance of SCH40 seamless steel pipe is typically in the range of 50–60 Joules.

Applications of SCH 40 seamless steel pipes

1. Building construction

SCH 40 seamless steel pipes are used in the construction of bridges, roads, factories, warehouses, buildings, etc.

2. Water and gas pipeline installation

SCH 40 seamless steel pipes are used in the installation of water, gas, and drainage systems in building engineering.

3. Equipment and machinery manufacturing

SCH 40 seamless steel pipes are also used in the manufacturing of equipment and machinery in many industries, including automobile manufacturing, industrial machinery, and agricultural machinery.

4. Oil and gas pipeline production

SCH 40 seamless steel pipes are also used in the production of oil and gas pipelines, ensuring the safety and stability of oil and gas transportation and storage.

5. Refrigeration system equipment manufacturing

SCH 40 seamless steel pipes are also used in the production of refrigeration system equipment in building engineering.

How to identify Schedule 40 steel pipes

1. Check pipe markings

Genuine products will be marked "SCH40," and the pipe body is usually printed with: ASTM A106 Gr.B / SCH 40 / NPS 4 / Heat No.

2. Measure wall thickness

Refer to the nominal diameter to wall thickness correspondence table. The outer diameter is fixed; compare the wall thickness with ASME B36.10M.

3. Observe the application scenario

Medium-pressure systems are more likely to use Schedule 40 steel pipes.

4. Consult the seamless pipe supplier

Obtain accurate technical parameters; the SCH grade will be clearly indicated in the Mill Test Certificate.

What are the differences between Schedule 40 and Schedule 80 steel pipes?

Schedule 40 steel pipes have a standard wall thickness (STD), meaning they have a thinner actual wall thickness, moderate pressure resistance, are lighter, and have a lower cost. They are commonly used in industrial piping, fire protection, and HVAC systems.

Schedule 80 steel pipes are thicker, with an even thicker actual wall thickness, higher pressure resistance, greater weight, and higher cost. They are commonly used in high-pressure, chemical, and steam systems.

FAQ

1. Is Schedule 40 steel pipe equivalent to STD pipe?

Within the NPS 1/8"–10" range, SCH 40 ≈ STD (Standard Weight), with the wall thickness being the same or very close.

However, for larger diameters (e.g., 12" and above), SCH 40 and STD may differ; the Schedule specification should be followed during project selection.

2. What is the difference between SCH 40 and SCH 40S?

SCH 40: Applicable to carbon steel and alloy steel pipes (ASME B36.10M)

SCH 40S: Applicable to stainless steel pipes (ASME B36.19M)

3. Does SCH 40 seamless steel pipe require third-party inspection?

For export projects, petrochemical projects, or government projects, third-party inspection (such as SGS, BV, TÜV) is generally recommended to ensure that dimensions, chemical composition, and mechanical properties meet standards.

4. Can SCH 40 seamless steel pipe be cut to length?

Yes. SCH 40 Seamless steel pipes typically support: random lengths (5.8–6.1 m / 11–12 m); fixed-length cutting; beveling, chamfering, painting, and anti-corrosion treatment.

Summary

In summary, SCH40 seamless steel pipe is a specification of seamless steel pipe with high strength, strong corrosion resistance, and high dimensional accuracy. It plays an important role in industries such as petroleum, chemical, shipbuilding, and heating. The use of SCH40 seamless steel pipe ensures stable pipeline operation while meeting the requirements of various media transportation.

Read more: Schedule 80 seamless steel pipe