How pipes are classified?

Steel pipes are classified based on various factors, including material composition, manufacturing process, dimensions, and their intended application. Here’s an overview of the main ways steel pipes are classified.

1. By Manufacturing Process

Seamless Steel Pipes:
These pipes are made without a seam or welded joint. They are created by extruding solid steel billets or by piercing a steel billet to form a hollow tube. Seamless pipes are known for their strength and reliability, making them suitable for high-pressure applications.

Welded Steel Pipes:
Welded pipes are formed by rolling steel plates or strips and welding the edges together. This process can include various types of welding methods, such as Electric Resistance Welding (ERW), Submerged Arc Welding (SAW), and others. Welded pipes are generally less expensive than seamless pipes and are used in many low to medium-pressure applications.

2. By Material

Steel pipes can be made from different types of steel depending on the alloy composition and properties required for specific applications:

Carbon Steel Pipes:
These are made from a mixture of iron and carbon. Carbon steel pipes are widely used for general purposes in construction, plumbing, and industrial applications.

Alloy Steel Pipes:
Made from a mixture of carbon and alloying elements such as chromium, molybdenum, and vanadium, alloy steel pipes are designed for high-strength, high-temperature, and high-pressure environments.

Stainless Steel Pipes:
Stainless steel pipes contain chromium and are highly resistant to corrosion. These are used in industries that require cleanliness and resistance to harsh chemicals or extreme temperatures, such as food processing, pharmaceuticals, and marine applications.

Galvanized Steel Pipes:
These pipes are coated with a layer of zinc to prevent corrosion. They are commonly used in plumbing and outdoor applications where protection from rust is necessary.

3. By Shape

Round Steel Pipes:
These are the most common type and are used in a variety of applications, including fluid transportation, structural work, and as supports in various industries.

Square and Rectangular Steel Pipes:
Used primarily for structural and construction purposes, square and rectangular pipes offer more stability and strength compared to round pipes.

Special Shape Pipes:
Custom-shaped pipes, like oval, triangular, or other geometries, are used in specific applications, often in decorative or unique structural designs.

4. By Dimensions

Outer Diameter (OD):
Steel pipes are classified based on their external diameter, which can vary widely. Standard pipe sizes range from small diameters of 1/8 inch to very large diameters of several feet.

Wall Thickness (Schedule):
The thickness of the pipe wall is crucial for determining the strength and pressure rating. Common classifications include Schedule 10, Schedule 40, Schedule 80, and Schedule 160, where a higher schedule number indicates a thicker wall and higher pressure resistance.

Pipe Length:
Steel pipes are typically available in standard lengths, but they can also be custom cut to required lengths depending on the project.

5. By Application

Steel pipes are often categorized by their intended use:

Oil and Gas Pipes (Casing, Line Pipes, Tubing):
Used in drilling, transportation, and extraction of oil and gas, these pipes must meet stringent strength and pressure requirements.

Water and Sewage Pipes:
Pipes designed for water supply, drainage, and sewage systems must be resistant to corrosion and withstand internal pressures.

Structural Steel Pipes:
These pipes are used for structural applications, such as scaffolding, construction, and in building frames.

Boiler Tubes:
These are used in power plants and other high-temperature applications. Boiler tubes need to withstand high pressure and heat.

Heat Exchanger Tubes:
Steel pipes used in heat exchangers need to have high thermal conductivity and resistance to high temperatures and corrosive fluids.

6. By Steel Grade

Steel pipes are often classified according to the specific grade of steel used to manufacture them. The grade refers to the quality and mechanical properties of the steel, such as yield strength, tensile strength, and hardness. Some commonly used steel grades for pipes include:

A106 (Gr. B): Standard grade for carbon steel pipes used in high-temperature services.

API 5L: Used for the oil and gas industry, specifically for line pipes.

A53: A general-purpose carbon steel pipe for low-pressure applications.

P5, P9, P22, etc.: Alloy steel grades used for high-temperature service in industries like power generation.

7. By Coating

Bare Steel Pipes:
These pipes are uncoated and are often used for applications where corrosion protection is not necessary.

Coated Steel Pipes:
These pipes are coated with various materials such as paint, epoxy, or powder coatings to improve corrosion resistance. Galvanized pipes are a common example.