The classification of seamless stainless steel tubes is as follows:
I. Classification according to manufacturing process
Stainless steel seamless pipes can be classified into hot rolled tubes, cold rolled tubes, cold drawn tubes and extruded tubes according to the manufacturing process. These processes have their own characteristics and are suitable for different application scenarios and precision requirements.
II. Classification according to cross-section shape
Stainless steel seamless pipes can be divided into round tubes and profiled tubes according to their cross-sectional shape. Among them, round pipe is the most widely used type due to its versatility and wide range of application.
Production and manufacturing methods:
There are various production methods for stainless steel seamless pipes, mainly including hot rolling, cold rolling, cold drawing and extrusion processes.
Stainless steel seamless steel pipe hot rolling production technology
I. Prepare raw materials
High-quality stainless steel tube billets are selected to remove surface defects and cut to the required length in preparation for subsequent processing.
II. Heating and perforating
After the tube blank is heated to high temperature, a hollow tube is formed on the perforator.
III. Rolling and sizing
The hollow pipe is rolled on the automatic pipe rolling machine, the wall thickness is adjusted by the diameter equalizing machine, and finally the diameter is determined on the sizing machine to ensure that the stainless steel pipe and other products for construction meet the specifications.
IV. Cool and straighten
The steel pipe is straightened after cooling with water spray to ensure straightness.
V. Quality inspection and storage
After passing the hydraulic test or flaw detection, mark and store in the warehouse.
Stainless steel seamless pipe cold rolling cold drawing process
I. Material pretreatment
(1) Blank preparation: Select SUS304/316L stainless steel seamless tube blank, perforated by medium frequency induction heating (temperature 1150-1200℃)
(2) Heat treatment process:
▶︎ gradient temperature control: 850-950℃ stage slow cooling, eliminate thermal stress
▶︎ vacuum annealing: hydrogen protection annealing at 600℃ for 2h, reducing hardness to HB≤150
▶︎ pickling passivation: electrolytic polishing + nitric acid passivation, surface roughness Ra≤0.4μm
II. Cold processing molding
(1) Equipment selection:
▶︎ Multi-station cold drawing machine (Φ15-89mm)
▶︎ Double roll continuous cold rolling mill (special for thin-wall pipe)
(2) Process control:
▶︎ 16-22 pass reduction, single pass reduction ≤3%
▶︎ wall thickness tolerance: ±0.08mm (ultra-thin tube) to ±0.15mm (thick wall tube)
▶︎ The finished product conforms to the size requirements of “Stainless Steel Pipe for Construction and Decoration” (GB/T 14308)
III. Mechanical property recovery
(1) Heat treatment specification:
▶︎ Solution treatment: 950-1050℃ water quenching (cooling medium pH 6.5-7.5)
▶︎ Low temperature aging: 450-500℃ air cooling, tensile strength ≥205MPa
(2) Straightening process:
▶︎ roller flattening machine (roller diameter Φ200-400mm)
▶︎ flatness ≤1.2mm/m (according to GB/T 2183 standard)
IV. Quality assurance system
(1) Online detection:
▶︎ Automatic flaw detector (sensitivity block CS-1-5, defect detection rate ≥98%)
▶︎ Laser caliper (accuracy ±0.02mm, sampling frequency 100Hz)
(2) Final inspection items:
▶︎ Dimensional tolerance: according to GB/T 14308 Table 3
▶︎ Surface condition: no scratches/indentations (according to EN 10277-5)
▶︎ Chemical composition: C≤0.08%, Cr≥18%, Ni≥9% (spectral analysis)
(3) Identity Management:
▶︎ laser inkjet code (production date/batch number/material)
▶︎ Quality Certificate (including third-party testing institution seal)
Stainless steel seamless pipe specification table:
| Product Name | Specification (Outer Diameter × Wall Thickness mm) | Length (m) | Outer Diameter Tolerance (mm) | Wall Thickness Tolerance (mm) |
|---|---|---|---|---|
| Stainless Steel Seamless Tube | 6×0.5 - 6×1.0 | 6 or 12 | ±0.10 | ±0.10 |
| Stainless Steel Seamless Tube | 8×0.8 - 8×1.2 | 6 or 12 | ±0.10 | ±0.10 |
| Stainless Steel Seamless Tube | 10×1.0 - 10×1.5 | 6 or 12 | ±0.10 | ±0.10 |
| Stainless Steel Seamless Tube | 12×1.0 - 12×2.0 | 6 or 12 | ±0.10 | ±0.10 |
| Stainless Steel Seamless Tube | 14×1.2 - 14×2.5 | 6 or 12 | ±0.10 | ±0.10 |
| Stainless Steel Seamless Tube | 16×1.5 - 16×3.0 | 6 or 12 | ±0.10 | ±0.10 |
| Stainless Steel Seamless Tube | 18×1.5 - 18×3.5 | 6 or 12 | ±0.10 | ±0.10 |
| Stainless Steel Seamless Tube | 20×1.5 - 20×4.0 | 6 or 12 | ±0.10 | ±0.10 |
| Stainless Steel Seamless Tube | 25×2.0 - 25×5.0 | 6 or 12 | ±0.15 | ±0.15 |
| Stainless Steel Seamless Tube | 32×2.5 - 32×6.0 | 6 or 12 | ±0.15 | ±0.15 |
| Stainless Steel Seamless Tube | 38×3.0 - 38×7.0 | 6 or 12 | ±0.15 | ±0.15 |
| Stainless Steel Seamless Tube | 45×3.5 - 45×8.0 | 6 or 12 | ±0.20 | ±0.20 |
| Stainless Steel Seamless Tube | 50×4.0 - 50×10.0 | 6 or 12 | ±0.20 | ±0.20 |
| Stainless Steel Seamless Tube | 60×4.5 - 60×12.0 | 6 or 12 | ±0.20 | ±0.20 |
| Stainless Steel Seamless Tube | 76×5.0 - 76×14.0 | 6 or 12 | ±0.25 | ±0.25 |
| Stainless Steel Seamless Tube | 89×6.0 - 89×16.0 | 6 or 12 | ±0.25 | ±0.25 |
| Stainless Steel Seamless Tube | 108×7.0 - 108×20.0 | 6 or 12 | ±0.30 | ±0.30 |
| Stainless Steel Seamless Tube | 133×8.0 - 133×25.0 | 6 or 12 | ±0.30 | ±0.30 |
| Stainless Steel Seamless Tube | 159×9.0 - 159×30.0 | 6 or 12 | ±0.30 | ±0.30 |
| Stainless Steel Seamless Tube | 219×10.0 - 219×40.0 | 6 or 12 | ±0.35 | ±0.35 |
| Stainless Steel Seamless Tube | 273×12.0 - 273×50.0 | 6 or 12 | ±0.40 | ±0.40 |
| Stainless Steel Seamless Tube | 325×14.0 - 325×60.0 | 6 or 12 | ±0.45 | ±0.45 |
| Stainless Steel Seamless Tube | 377×16.0 - 377×70.0 | 6 or 12 | ±0.50 | ±0.50 |
| Stainless Steel Seamless Tube | 426×18.0 - 426×80.0 | 6 or 12 | ±0.50 | ±0.50 |
escription:
1、Specifications：Outside diameter x wall thickness, unit is millimetre (mm).
2、Length：Standard length is 6 metres or 12 metres, also can be customised according to customers’ requirements.
3、Tolerance range：Outside diameter and wall thickness tolerance in accordance with international standards (such as ASTM, JIS) requirements.
4、Applicable standards: Export products usually need to comply with international standards such as ASTM, JIS or ISO.
| Country/Region | Standard Number | Standard Name | Scope of Application |
|---|---|---|---|
| China | GB/T 14975-2012 | Structural Stainless Steel Seamless Tubes | Used in building structures, mechanical manufacturing, and similar fields. |
| China | GB/T 14976-2012 | Stainless Steel Seamless Tubes for Fluid Conveyance | Used in chemical processing, food processing, and other fluid conveyance applications. |
| China | GB 13296-2023 | Stainless Steel Seamless Tubes for Boilers and Heat Exchangers | Used in boilers and heat exchangers. |
| China | GB/T 3090-2020 | Small-Diameter Stainless Steel Seamless Tubes | Used in aerospace, medical devices, and other applications requiring small-diameter tubes. |
| China | GB 5310-2017 | Seamless Tubes for High-Pressure Boilers | Used in high-pressure boilers. |
| China | GB 9948-2013 | Seamless Tubes for Petroleum Cracking | Used in petroleum cracking processes. |
| USA | ASTM A213 | Ferritic and Austenitic Alloy Steel Seamless Tubes for Boilers and Heat Exchangers | Used in boilers and heat exchangers. |
| USA | ASTM A269 | Austenitic Stainless Steel Seamless and Welded Tubes for General Purposes | Used in general industrial applications. |
| USA | ASTM A312 | Austenitic Stainless Steel Seamless and Welded Tubes | Used in chemical processing, food processing, and similar applications. |
| Japan | JIS G3448 | Stainless Steel Tubes for General Piping | Used in general piping systems. |
| Japan | JIS G3463 | Stainless Steel Tubes for Boilers and Heat Exchangers | Used in boilers and heat exchangers. |
| International | ISO 1127 | Stainless Steel Seamless Tubes | Used in international applications for stainless steel tubes. |
| EU | EN 10312 | Stainless Steel Tubes for Fluid Conveyance | Used in fluid conveyance applications. |
| EU | EN 10216-7 | Stainless Steel Seamless Tubes | Used in corrosion-resistant steel seamless tubes. |
Description:
The above tables cover Chinese, US, Japanese, EU and international standards.
They are suitable for different application scenarios, including building structures, fluid transmission, boilers, heat exchangers, chemicals, food processing, aerospace and medical devices.
These standards ensure that the quality and performance of seamless stainless steel tubes meet international requirements.
Seamless Stainless Steel Tubes Common Materials：
Stainless steel seamless pipe can be divided into several series and grades according to the chemical composition and performance characteristics. The following is a detailed introduction of common materials:
1. 200 series
(1) 201 (1Cr17Mn6Ni5N)
A: Chemical composition: C ≤ 0.15, Si ≤ 1.00, Mn 5.5-7.5, P ≤ 0.060, S ≤ 0.030, Ni 3.5-5.5, Cr 16.0-18.0, N ≤ 0.25.
B: Performance characteristics: 201 stainless steel is a low-nickel austenitic stainless steel with a certain degree of acid and alkali resistance, high density, no bubbles or pinholes after polishing. Due to its low cost, it is widely used in decorative tubes, industrial tubes and shallow drawn products.
C: Application areas: commonly used in the production of watch cases, watch bands, kitchen utensils, sinks, etc..
(2) 202 (1Cr18Mn8Ni5N)
A: Chemical composition: similar to 201, but with higher manganese content, usually around 8%.
B: Performance characteristics: compared with 201, 202 has better strength and toughness, but corrosion resistance is slightly inferior to 300 series.
C: Application areas: mainly used in building decoration, furniture and other fields.
2. 300 series
(1) 301 (1Cr17Ni7)
A: Chemical composition: C≤0.15, Si≤1.00, Mn≤2.00, P≤0.045, S≤0.030, Ni 6.5-8.0, Cr 16.0-18.0.
B: Performance characteristics: 301 stainless steel has good corrosion resistance and formability, but higher strength, suitable for deep-drawn processing.
C: Application areas: commonly used in the manufacture of tableware, kitchen equipment, automotive parts and so on.
(2) 302 (1Cr18Ni)
A: Chemical composition: similar to 301, but with higher chromium content.
B: Performance characteristics: corrosion resistance is better than 301, suitable for use in harsher environments.
C: Application areas: used in the manufacture of tableware, chemical equipment, etc..
(3) 304 (0Cr18Ni9)
A: Chemical composition: C ≤ 0.08, Si ≤ 1.00, Mn ≤ 2.00, P ≤ 0.045, S ≤ 0.030, Ni 8.0-10.5, Cr 18.0-20.0.
B: Performance characteristics: 304 is the most widely used stainless steel material, with good corrosion resistance, heat resistance and low temperature performance.
C: Application areas: widely used in food processing equipment, chemical equipment, medical equipment and so on.
(4) 304L (00Cr19Ni10)
A: Chemical composition: ultra-low carbon version of 304, C ≤ 0.03.
B: Performance characteristics: intergranular corrosion resistance is better than 304, suitable for welding applications.
C: Application areas: commonly used in chemical vessels, pipelines, etc..
(5) 321 (1Cr18Ni9Ti)
A: Chemical composition: similar to 304, but with the addition of titanium.
B: Performance characteristics: excellent intergranular corrosion resistance, high temperature strength.
C: Application areas: used in aviation, chemical, automotive and other fields.
(6) 316 (0Cr17Ni12Mo2)
A: Chemical composition: C ≤ 0.08, Si ≤ 1.00, Mn ≤ 2.00, P ≤ 0.045, S ≤ 0.030, Ni 10.0-14.0, Cr 16.0-18.0, Mo 2.0-3.0.
B: Performance characteristics: corrosion resistance is better than 304, especially for chlorine ion corrosion resistance is stronger.
C: Application areas: widely used in marine equipment, chemical equipment, medical equipment, etc..
(7) 316L (0Cr17Ni14Mo2)
A: Chemical composition: ultra-low carbon version of 316, C ≤ 0.03.
B: Performance characteristics: excellent intergranular corrosion resistance, suitable for welding.
C: Application: Used in chemical pipelines, marine engineering, etc.
(8) 310S (0Cr25Ni20)
A: Chemical composition: C ≤ 0.08, Si ≤ 1.50, Mn ≤ 2.00, P ≤ 0.045, S ≤ 0.030, Ni 19.0-22.0, Cr 24.0-26.0.
B: Performance characteristics: excellent high temperature resistance, suitable for use in high temperature environment.
C：Applications：Used in boilers, heat exchangers and so on.