JIS G3101 SS400 is a very common and widely used material grade for manufacturing Longitudinal Submerged Arc Welded (LSAW) pipes [citation:1, citation:2, citation:3, citation:5]. This combination is a standard product offered by numerous global manufacturers for a wide range of structural and engineering applications [citation:1, citation:2, citation:5].
It is important to understand that "JIS G3101 SS400" refers to the material grade of the steel plate used as the raw material. The finished LSAW pipe product is manufactured to meet the specifications of this grade and is available from suppliers who list JIS G3101 grades in their production range [citation:1, citation:2, citation:5].
Here is the detailed specification for a JIS G3101 SS400 LSAW pipe:
Key Specifications
| Attribute | Description |
|---|---|
| Material Standard | JIS G3101: Japanese Industrial Standard for "Rolled Steels for General Structure" [citation:2, citation:6]. |
| Steel Grade | SS400: The most common grade. "SS" stands for "Structural Steel," and "400" indicates the minimum tensile strength of 400 MPa [citation:2, citation:6]. |
| Process | LSAW (Longitudinal Submerged Arc Welding) : Pipes are manufactured by forming steel plates into a cylinder (using JCOE, UOE, or similar forming processes) and welding the longitudinal seam both internally and externally using a submerged arc process. This process is well-suited for producing large-diameter pipes with thick walls [citation:1, citation:2, citation:4]. |
| Chemical Composition (max %) [citation:1, citation:3, citation:6] | |
| Carbon (C): Not specified (typically ≤0.16% based on supplier data) | |
| Phosphorus (P): ≤ 0.050 | |
| Sulfur (S): ≤ 0.050 | |
| Mechanical Properties [citation:1, citation:3, citation:6] | |
| Yield Strength: ≥ 245 MPa (for thickness ≤16mm) [citation:1, citation:3, citation:6] | |
| Yield Strength: ≥ 235 MPa (for 16mm < t ≤ 40mm) [citation:1, citation:3, citation:6] | |
| Yield Strength: ≥ 215 MPa (for t ≥ 100mm) [citation:1, citation:3, citation:6] | |
| Tensile Strength: 400-510 MPa [citation:1, citation:3, citation:6] | |
| Typical Size Range [citation:1, citation:4] | |
| Outside Diameter: 219 mm to 1625 mm (approx. 8" to 64") [citation:1, citation:4] | |
| Wall Thickness: 6.35 mm to 60 mm [citation:1, citation:4] | |
| Length: 2 m to 18 m (customizable, up to 32 m available for piling) [citation:1, citation:4] | |
| Manufacturing Steps [citation:2, citation:5] | 1. Steel plate selection and edge milling. 2. Edge crimping and forming using JCOE or UOE processes. 3. Internal and external submerged arc welding. 4. Mechanical expanding (for UOE/JCOE). 5. Non-destructive testing (Ultrasonic, X-ray). 6. Hydrostatic testing. 7. End facing and beveling. |
| Common Applications [citation:2, citation:3, citation:5, citation:6] | General structural engineering; building construction frames and columns; bridge components; piling foundations; shipbuilding; machinery manufacturing; low-pressure fluid transmission (water, gas, oil); offshore projects; infrastructure projects. |
| Certification | Mill Test Certificate typically to EN 10204 / 3.1 or equivalent [citation:1, citation:2]. |
🔍 Key Points to Understand
What "SS400" Means: The "SS" stands for "Structural Steel," and "400" indicates the minimum tensile strength of 400 MPa. Unlike many other structural steel grades, SS400 does not have a specified minimum yield strength in the JIS G3101 standard [citation:2, citation:6]. However, yield strength values are provided based on product thickness and are commonly referenced by manufacturers [citation:1, citation:3, citation:6].
Chemical Composition: The JIS G3101 standard only specifies maximum limits for phosphorus (≤0.050%) and sulfur (≤0.050%) for SS400. Carbon, manganese, and other elements are not specified in the standard, allowing flexibility for manufacturers [citation:1, citation:3, citation:6]. Supplier data typically shows carbon content around ≤0.16% .
Yield Strength Values: While the standard does not mandate a yield strength, it provides reference values based on product thickness . For plates ≤16mm, the yield point is ≥245 MPa; for 16-40mm thickness, ≥235 MPa; for >100mm thickness, ≥215 MPa [citation:1, citation:3, citation:6].
Comparison with Other Standards: SS400 is comparable to ASTM A36 (USA) and GB/T 700 Q235B (China) . It is the most economical and widely used grade in the JIS G3101 family .
Related Product Standards: The finished pipe product is often governed by additional standards such as JIS G3444 (carbon steel pipes for general structural purposes), which specifies dimensional tolerances, hydrostatic test pressure, etc., while calling for material to conform to JIS G3101 .
Weldability: SS400 has excellent weldability due to its low carbon equivalent, making it suitable for common welding methods including submerged arc welding (SAW), which is the process used for LSAW pipe manufacturing [citation:2, citation:3, citation:6].
Summary
In conclusion, JIS G3101 SS400 LSAW pipe is a well-established, versatile product that combines the reliable properties of SS400 structural steel with the robust LSAW manufacturing process [citation:1, citation:2, citation:5]. It is the most common and economical grade in the JIS G3101 family, widely used for structural applications, building frames, piling foundations, and low-pressure fluid transmission [citation:2, citation:5, citation:6]. The LSAW process enables the production of large-diameter pipes with thick walls (up to 60 mm), making it suitable for major infrastructure and construction projects [citation:1, citation:4]. When specifying, it is best practice to reference both the material grade and any applicable product standards (e.g., JIS G3444) based on the intended application .
