What is a Seamless Steel Tube?
Seamless steel tubes, also known as drawn steel tubes, have become increasingly popular in recent times. As the name suggests, they are produced without welding, using extrusion and special rolling (hot rolling and cold drawing) methods. The production of seamless steel tubes is quite complex and costly, but unlike welded steel tubes, they do not have an ITAB (heat-affected zone) at the weld, which gives them superior strength. Steel tubes are categorized into two types based on their manufacturing methods: welded steel tubes and seamless (drawn steel) tubes. Welded tubes are formed by bending a flat strip and then welding it together to create a tube. They are further divided into spiral-welded and longitudinal-welded tubes.
Seamless Drawn Steel Tubes
Seamless drawn steel tubes are produced by heating a billet until it becomes liquid, then pouring it into molds to form the desired tube shape. Since no welding is involved, seamless tubes exhibit better homogeneity and higher corrosion resistance. For this reason, they are preferred in applications requiring high strength and durability. There are two main methods used for manufacturing seamless drawn steel tubes:
1. Extrusion: This method is divided into two subgroups: direct extrusion and indirect extrusion. In direct extrusion, solid and hollow metal billets are used, while in indirect extrusion, only hollow billets are employed. The tube's cross-section is determined by the mandrel attached to the piston in the process.
2. Special Rolling: The key principle in special rolling is to perforate a metal block using hot processing. After perforation, the next step is determined by the required wall thickness and tube diameter. If a thicker wall is required, hot processing is used; for better mechanical properties, smoother surfaces, and precise dimensional tolerances, cold drawing is employed.
Types of Seamless Drawn Steel Tubes
Seamless drawn steel tubes are divided into two types based on their manufacturing method:
1. Hot Drawn Tubes: These are obtained by perforating metal blocks, which are then processed with hot methods to create cylindrical shapes. They are generally used for smaller diameter tubes but can be customized for diameter and wall thickness based on customer needs.
2. Cold Drawn Tubes: These tubes are precisely drawn, with a linearity of 0.5-1/1000 mm. Cold drawn tubes have better surface quality and more accurate dimensional tolerances than hot drawn tubes.
Applications of Seamless Drawn Steel Tubes
• Petroleum and Gas Subsea Tubes: These are used extensively in the energy sector, at fuel stations, oil refineries, gas pipelines inside buildings, natural gas power plants, and more. Typically, seamless steel pipe standards such as ASME, API, and ASTM, or API 5B standards (Grade A, Grade B), are used. These pipes are suitable for underground and above-ground installations and offer excellent long-term durability and reliability.
• Heat Exchanger Tubes: These are used to transfer heat between two different fluids without allowing them to mix. Hot drawn seamless tubes are commonly used in energy plants and petrochemical industries, with materials such as A210, A192, and A179 standards.
• Boiler Tubes: These tubes are used in biomass combustion systems, pressure vessels, and various types of cooking ovens. Thin wall thickness is preferred to enhance heat transfer. Reliability in boiler tubes is critical, so the selection of the material is very important. These tubes are typically made of alloyed or non-alloyed steel and are produced according to European standards such as EN10216-2.
• Casing Tubes: Used in drilling operations for extracting underground water, steam, hot water, natural gas, oil, and solids (such as salt). API standard steel materials are commonly used for casing tubes. The wall thickness, pipe diameter, steel material, and thread type vary based on casing configuration and well depth. Casing pipe diameters typically range from 4 ½” (114.3 mm) to 20” (508 mm), with three types of threads used: STC (Short Thread Casing), LTC (Long Thread Casing), and BTC (Buttress Thread Casing), according to API quality standards.
• Mechanical Tubes: These tubes are used in general machinery manufacturing, automotive industry, defense industry, hydraulic systems, wagon manufacturing, agricultural tools, and more. Quality standards such as St-52, DIN 1629, and special materials like 24Mn4 for specific applications are commonly used.
Seamless drawn steel tubes are crucial for applications that require high strength, precision, and durability, making them the preferred choice in various industries like energy, petrochemicals, and mechanical manufacturing.
In what grades are seamless steel pipes manufactured?
Seamless steel pipes are manufactured according to DIN 2448 measurement standards, using alloyed and low-carbon steels such as ASTM A106, ASTM A53, DIN 1629, DIN 17175, API 5B, API 5CT, API 5L, TSE 381, TSE 301, TSE 346, and others.
Seamless steel pipes are produced in grades compliant with European standards. The quality of seamless steel pipes is determined based on their application area.
Precision seamless pipes and cold-drawn pipes are manufactured according to the EN 10305-1 quality standard, using steels such as E235, E355, E275, E410, 26Mo2, C35E, C45E, 42CrMo4, 25CrMo4. Steel E355+C is manufactured according to the EN 10305-1 standard.
• Outer Diameter: 4 mm – 245 mm
• Wall Thickness: 0.5 mm – 25 mm
Seamless steel pipes manufactured with steels that have high toughness at low temperatures are produced according to the DIN 17173 standard, using St 35N steel.
Heat-resistant seamless pipes are manufactured according to the EN 10216-2 (DIN 17175) standard, typically using St35.8 and St45.8 steels.
• Outer Diameter: 17.2 mm - 660 mm
• Wall Thickness: 2 mm – 75 mm
Seamless steel pipes for boilers and heaters (BS 3059) are manufactured according to EN 10216-1 and EN 10216-2 standards.
• Outer Diameter: 17.2 mm - 660 mm
• Wall Thickness: 2 mm – 75 mm
The P235 GH material, according to EN 10216 and EN 10028, is a weldable carbon steel suitable for high-temperature boiler pipes. P235GH-TC1 seamless pipes are manufactured according to EN 10216-2 and EN 10217-2 standards for high-temperature and high-pressure applications.
Boiler tube dimensions:
• Length: 5.00 m - 18.30 m
• Wall Thickness: 2.0 mm - 12.7 mm
• Outer Diameter: 21.3 mm - 339.7 mm
The prices of boiler pipes vary according to the material quality, dimensions, diameter, and wall thickness.
Seamless steel pipe grades:
Grade Group Product Standard
Heat-treated steels 42CrMo4
Case-hardening steels 16MnCr5
Carbon steels S235JR, P235GH, S275JR, S355JR
Hot-rolled seamless pipes EN 10210-1, EN 10297
Pressure and high-temperature resistant pipes EN 10216-2
Cold-drawn seamless pipes EN 10305-1
Oil pipes API 5L PSL2
Drilling and protection pipes API 5CT, API 5D
High-temperature seamless pipes ASTM A106
Technical tables for pipes:
• Pipe weight calculation
• Pressure calculation
Seamless Stainless Steel Pipe Sections: Seamless stainless steel pipe sections consist of the outer diameter and wall thickness. Outer diameters range from 21 mm to 1000 mm, and wall thicknesses range from 2 mm to 150 mm.
Seamless Pipe Manufacturing
Seamless pipes can be manufactured through two methods:
a. Extrusion Method
b. Special Rolling Methods
These pipes are typically produced through hot processes, although cold processes can be used for very soft metallic materials.
a) Extrusion Method for Pipe Manufacturing
In pipe extrusion, cylindrical metal blocks (solid or hollow blocks) are used. Pipes are manufactured using direct extrusion of solid and hollow blocks, or indirect extrusion with hollow blocks. A punch is used to obtain the pipe section during this process.
b) Seamless Pipe Manufacturing by Special Rolling Methods
This process involves perforating a cylindrical metal block through hot treatment. The subsequent manufacturing steps depend on the pipe diameter and wall thickness. In the Mannesmann pipe production process, a hot cylindrical block is perforated using a press, with rollers that rotate at slightly inclined angles, followed by a perforation process to obtain thick-walled pipes.
Seamless Steel Pipe Prices
The price of steel pipes used in the industry varies depending on the diameter, shape, wall thickness, and pipe standard. Prices are determined according to the diameter, wall thickness, and quality standard of the pipe. Hasçelik.com provides services throughout Turkey, with a wide network of warehouses and efficient logistics in cities like Istanbul, Ankara, Adana, Izmir, and Diyarbakir. Visit hascelik.com for more information about our range of products, including iron pipes, steel pipes, and their characteristics and sizes.
Types of Seamless Steel Pipes:
• Boiler Pipes
• Industrial Pipes
• Steel Pipes / Cold-drawn Steel Pipes
• Drilling Pipes 1000
• Automotive Pipes
• Energy Line Pipes (API and others)
• Construction Pipes
• Hydraulic Cylinder Pipes
