The seamless pipe (SMLS full form) (https://www.eastern-steels.com/product/seamless-steel-pipe.html) can be classified according to various standards, each containing multiple types. They can be categorized by manufacturing method, cross-sectional shape, application, material, and precision. The following is a detailed summary of seamless pipe classifications.

Classification by Production Method
1. Hot-rolled Seamless Pipes (https://www.eastern-steels.com/newsdetail/hot-rolled-seamless-steel-tube.html)
Production Process: Manufactured through processes such as heating a round pipe billet, piercing, three-roll skew rolling or continuous rolling, pipe removal, sizing (or reduction), cooling, straightening, and hydrostatic testing (or flaw detection).
Features: High production efficiency, low cost, suitable for mass production.

2. Cold-rolled (Cold-drawn) Seamless Pipes (https://www.eastern-steels.com/newsdetail/cold-drawn-pipe-vs-cold-rolled-pipe.html)
Production Process: Manufactured from round pipe billets through processes such as heating, piercing, heading, annealing, pickling, oiling (copper plating), multi-pass cold drawing (cold rolling), billet pipe formation, heat treatment, straightening, and hydrostatic testing (flaw detection).
Features: High precision, good surface quality, but low production efficiency and higher cost.

3. Extruded Seamless Pipes
Production Process: Metal billets are extruded into seamless pipe shapes using an extrusion process.
Features: Suitable for manufacturing SMLS pipes of special shapes or materials.

4. Pipe Jacking
Production Process: A special method for producing seamless pipes, using a jacking process to push metal billets into SMLS pipes.
Features: Suitable for manufacturing long-distance, large-diameter seamless pipes.

Classification by Cross-sectional Shape
1. Circular Seamless Pipes
Features: The most common shape of seamless pipes, with a hollow cross-section and no seams around the perimeter.
Applications: Widely used in various fluid transportation and structural support applications.

2. Irregularly Shaped Seamless Pipes
Classification: Includes square, oval, triangular, hexagonal, seed-shaped, star-shaped, and finned pipes.
Features: Designed according to specific needs to meet the requirements of different applications.
Applications: Such as automotive drive shafts, oil drill pipes, and pipes for building structures.

Classification by Use
1. Structural Seamless Pipes
Applications: Used for general structures and mechanical structures, such as buildings, bridges, and machinery manufacturing.

2. Seamless Pipes for Fluid Transportation
Applications: Used for transporting fluids such as water, oil, and gas, such as pipeline systems in the petroleum, natural gas, and chemical industries.

3. Seamless Steel Pipes for Boilers
Classification: Includes seamless steel pipes for low and medium pressure boilers and seamless steel pipes for high pressure boilers.
Applications: Used in the manufacture of boiler heating surface pipes, superheated steam pipes, boiling water pipes, etc.

4. Seamless Steel Pipes for Geological Drilling
Applications: Used by geological departments for core drilling, such as in the exploration of oil, natural gas, and mineral resources.

5. Seamless Steel Pipes for Petroleum Cracking
Applications: Suitable for furnace pipes, heat exchangers, and pipelines in petroleum refineries, used in the petroleum cracking process.

6. High-Pressure Seamless Steel Pipes for Fertilizer Equipment
Applications: Used in the manufacture of fertilizer equipment and pipelines, capable of withstanding high pressure and corrosive media.

7. Seamless Steel Pipes for Marine Engineering
Applications: Used in the manufacture of pressure-resistant piping systems, boilers, and superheaters for ships, meeting the requirements for use in harsh environments.

8. Seamless Steel Pipes for Automobile Axle Sleeves
Applications: Used in the manufacture of automobile axle sleeves and drive axle housing pipes, capable of withstanding vibrations and impacts during vehicle operation.

9. Other Special-Purpose Seamless Pipes
Such as high-pressure OCTG pipes for diesel engines, precision inner diameter SMLS pipes for hydraulic and pneumatic cylinders, etc., each suitable for equipment and pipelines in specific fields.

Classification by Material
1. Carbon Steel Seamless Pipe (https://www.eastern-steels.com/products/carbon-steel-seamless-line-pipe.html)
Material: Made of ordinary carbon structural steel or high-quality carbon structural steel.
Application: Seamless pipes made of low-carbon steel such as 10#, 20#, and 45# are mainly used for fluid transportation pipelines.

2. Alloy Seamless Pipes
Material: Made of low-alloy steel or alloy steel.

Application: SMLS pipes made of low-alloy structural steel such as 16Mn and 5MnV, or alloy structural steel such as 40Cr, 30CrMnSi, 45Mn2, and 40MnB, are used to manufacture mechanical parts or pipelines that withstand high pressure.

3. Stainless Steel Seamless Pipes
Material: Made of stainless steel.
Application: Possessing corrosion resistance, widely used in corrosion-resistant pipelines, structural components, and parts in chemical, petroleum, light textile, medical, food, and machinery industries.

Classification by Precision
1. Ordinary Seamless Pipes
Characteristics: Relatively low precision, average surface quality.
Applications: Suitable for applications where high precision is not required.

2. Precision Seamless Pipes
Characteristics: High precision, good surface quality, and excellent inner and outer wall finish.
Applications: Such as precision inner diameter SMLS pipes for hydraulic and pneumatic cylinders, suitable for applications requiring high precision.

Summary
In conclusion, there are many types of seamless steel pipes, each with its own characteristics. When selecting seamless steel pipes, the appropriate type and material should be chosen based on actual needs and applications to ensure performance and service life.

Read more:
What are Seamless Pipes Made of: https://www.eastern-steels.com/newsdetail/what-are-seamless-pipes-made-of.html
or
Seamless Pipe vs. EFW Pipe: https://www.eastern-steels.com/newsdetail/seamless-pipe-vs-efw-pipe.html