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0102030405
China Suppliers Factory for JIS G3444 Carbon Steel Pipes for General Structural Applications
Ordering Information
When ordering, the following must be specified:
- Standard number (JIS G 3444)
- Steel grade (e.g., STK290, STK400)
- Dimensions (outer diameter, wall thickness, length)
- Type of tube (plain end, threaded, etc.)
- Quantity
Main Steel Grades & Mechanical Properties
| Steel Grade | Tensile Strength (MPa) Min | Yield Strength (MPa) Min | Elongation (%) Min |
|---|---|---|---|
| STK290 | 290 | – | 30 |
| STK400 | 400 | 235 | 25 |
| STK490 | 490 | 325 | 20 |
| STK500 | 500 | 355 | 18 |
Manufacturing Process
⚙️ Tubes are manufactured by welding (electric resistance welding, arc welding, etc.) or seamless processes.
Chemical Composition (Typical, % Max)
- Carbon (C): Varies by grade (e.g., ≤0.30% for STK290)
- Phosphorus (P): ≤0.040%
- Sulfur (S): ≤0.040%
Inspection Requirements
- Tensile test (for mechanical properties)
- Bend test or flattening test (for ductility)
- Hydrostatic test or non-destructive testing (NDT) (for weld integrity)
- Visual inspection (surface defects, dimensions)
Surface Condition & Defects
- Tubes must be free from harmful defects.
- Light surface imperfections may be permitted if within tolerance.
Marking
Each tube must be marked with:
- Manufacturer's name or trademark
- Steel grade (e.g., STK400)
- Size (outer diameter × wall thickness)
- Standard number (JIS G 3444)
🔄 Latest Revision (2025 Updates)
- Enhanced NDT requirements for welded joints.
- Revised chemical composition limits for improved weldability.
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❓ Frequently Asked Questions
What is JIS G 3444 and what is it used for?
JIS G 3444 is a Japanese Industrial Standard that specifies carbon steel tubes used for general structural purposes, such as building construction, bridges, and civil engineering applications. It covers both welded and seamless tube types.
What steel grades are available under JIS G 3444?
JIS G 3444 includes four main steel grades: STK290, STK400, STK490, and STK500. Each grade differs in tensile strength, yield strength, and elongation properties to suit various structural requirements.
What information is required when placing an order for JIS G 3444 tubes?
When ordering, you must specify the standard number (JIS G 3444), steel grade, outer diameter, wall thickness, length, type of tube end (plain end or threaded), and the required quantity.
What types of inspections are required for JIS G 3444 tubes?
Required inspections include tensile testing for mechanical properties, bend or flattening tests for ductility, hydrostatic or non-destructive testing (NDT) for weld integrity, and visual inspection for surface defects and dimensional accuracy.
How are JIS G 3444 steel tubes manufactured?
JIS G 3444 tubes are produced through welding methods such as electric resistance welding (ERW) and arc welding, as well as seamless manufacturing processes, depending on the application and grade requirements.
What are the 2025 updates to the JIS G 3444 standard?
The latest 2025 revision includes enhanced non-destructive testing (NDT) requirements for welded joints to improve quality assurance, as well as revised chemical composition limits designed to enhance weldability and overall structural performance.