JIS G3444 Carbon steel pipe material Introduction (Core Export Grades)

STK400 is the most common low-carbon structural steel, with a carbon content ≤0.25%. It offers a good balance of strength and weldability, providing high cost-effectiveness. It is mainly used in building frames, general structures, and basic load-bearing applications such as general supports.

STK490 is a medium-to-high strength grade, with a carbon content ≤0.18% and a manganese content ≤1.65%. It utilizes alloy strengthening to enhance resistance to deformation and maintains stable mechanical properties. It is suitable for heavy-duty structures, engineering machinery supports, and high-stress components where strength is a requirement.

STK500 is a high-strength grade with a yield strength ≥355MPa. Employing manganese-based strengthening technology, it boasts excellent toughness and load-bearing capacity, making it suitable for high-load and high-support requirements. It is primarily used in high-rise building columns, heavy equipment foundations, and scaffolding applications.

STK290 is a low-strength grade, used only in simple structures and non-load-bearing components, such as temporary supports and lightweight frames. Demand for it in export projects is relatively low.

STK540 is an ultra-high strength grade with a yield strength ≥390MPa. It achieves high strength through efficient alloy ratio and is suitable for extreme high load scenarios, such as super high-rise buildings, large bridges, and special heavy-duty structures.

Product Advantages

JIS G3444 is the core standard for structural steel pipes in Japan, Southeast Asia, and Oceania, with no project acceptance threshold. It is suitable for markets in Japan, Australia, Southeast Asia, and the Middle East, and can be directly used in projects conforming to local standards. Covering all strength grades from light to heavy load, it can meet diverse needs for scaffolding, foundation piles, and building frames. Available in a full range of specifications with outer diameters of 21.7–1016mm and wall thicknesses of 1.0–12.7mm, it offers high container loading efficiency. Excellent processing and welding performance. Low carbon/low alloy design with low carbon equivalent reduces the risk of cold cracking during welding, suitable for manual arc welding, TIG welding, and submerged arc welding. Easy to bend, flare, and drill, resulting in high on-site construction efficiency and rapid delivery.

Chemical composition (mass fraction %)

Mechanical properties(At room temperature, wall thickness ≤ 16mm)

Statistics on the popular models and common specifications of carbon steel pipes

Select materials based on application

For general fluid transportation (water, gas, oil): 20#, Q235B, A53 Gr.B, STPG370

The best cost-performance ratio, globally applicable

For high-temperature / steam / boiler pipes: A106 Gr.B, 20G, 15CrMoG, P235TR1/P235GH

Better resistance to high temperature and pressure

For oil and gas pipelines: API 5L Gr.B, X42, X52, X60

High strength and good toughness, suitable for long-distance pipelines

For low-temperature environments (cold storage, LNG support): A333 Gr.1/Gr.3, 16MnDG

Resistant to low temperature without cracking

For structural pipes (supports, machinery, steel structures): Q355B (old 16Mn), St44.2, A36

High strength and good load-bearing capacity