Stainless steel pipes are classified based on several factors, including their material grade, application, manufacturing process, and structural characteristics. Here are the main classifications:
1. Based on Material Grade
Stainless steel pipes are often classified by their specific alloy composition. Common grades include:
- Austenitic Stainless Steel: Contains high levels of chromium and nickel, making it highly resistant to corrosion and non-magnetic. Common grades are 304, 316, and 321, often used in applications requiring high corrosion resistance.
- Ferritic Stainless Steel: Contains higher chromium content but lower carbon, making it magnetic and less ductile. Common grades include 430 and 409, often used in automotive and industrial equipment.
- Martensitic Stainless Steel: Contains moderate to high levels of carbon, making it hard and strong but less resistant to corrosion. Common grades are 410 and 420, often used for applications requiring high strength and wear resistance.
- Duplex Stainless Steel: Combines both austenitic and ferritic structures, offering improved strength and corrosion resistance. Common grades are 2205 and 2507, used in chemical, oil, and gas industries.
- Precipitation-Hardening Stainless Steel: Contains elements like aluminum and copper, which can be heat-treated to enhance strength. Common grades include 17-4 PH and 15-5 PH, used in aerospace and high-stress applications.
2. Based on Manufacturing Process
- Seamless Pipes: Made by extrusion or piercing a solid billet, seamless pipes have no welded seam, which gives them greater strength and corrosion resistance. They are commonly used in high-pressure applications.
- Welded Pipes: Made by rolling and welding a steel sheet or strip, welded pipes are more economical than seamless pipes and are used for low- to moderate-pressure applications. They can further be divided into:
- ERW (Electric Resistance Welded): Used for oil and gas transportation, plumbing, and more.
- LSAW (Longitudinal Submerged Arc-Welded): Used for large-diameter pipes in oil and gas transmission.
- DSAW (Double Submerged Arc-Welded): Used for pipelines with larger diameters and thicker walls.
3. Based on Application
- Sanitary Pipes: Used in food, beverage, and pharmaceutical industries, these pipes have a high surface finish to prevent contamination and are easy to clean.
- Pressure Pipes: Designed to withstand high-pressure environments, they are used in applications like boilers and heat exchangers.
- Mechanical Tubing: Used for structural and mechanical purposes, these pipes are valued for their strength and formability.
- Ornamental Pipes: Used in decorative applications, these pipes have a polished finish and are used in railings, automotive trim, etc.
4. Based on Structural Characteristics
- Round Pipes: The most common type, used in many applications, including plumbing and construction.
- Square Pipes: Commonly used in structural and architectural applications.
- Rectangular Pipes: Used in construction and manufacturing for frames, supports, and other structural applications.
5. Based on Thickness and Schedule
Stainless steel pipes are also classified based on their wall thickness, often referred to as “schedule” (SCH). Examples include SCH 10, SCH 40, SCH 80, etc., with higher schedules indicating thicker walls suitable for higher-pressure applications.
Each classification suits different applications, so selecting the right type of stainless steel pipe depends on the specific requirements, including corrosion resistance, strength, and temperature tolerance.