JIS G3444


JIS G3444 Steel Pipe

JIS G3444 is a Japanese standard that specifies the requirements for welded or seamless carbon steel tubes used in various structural applications. These applications range from general structural purposes, civil engineering, and architecture to steel towers, scaffoldings, struts, and piles for suppressing landslides. The tubes manufactured under this standard are essential for ensuring the stability and durability of various structures. At UNIACERO, we pride ourselves on producing steel tubes that not only meet but exceed the JIS G3444 standard, ensuring our clients receive the best quality for their projects.

JIS G3444 Specification

Our JIS G3444 steel tubes come with a variety of specifications to cater to different needs. They are available in grades ranging from STK290 to STK540, ensuring versatility in application. The tubes are manufactured using the hot-rolled method, guaranteeing durability and resilience. Furthermore, we offer various surface treatments such as coating, painting, and galvanizing to enhance the tube’s resistance to environmental factors. Whether you require tubes for a small project or a large-scale construction, our range of specifications ensures you find the perfect fit.

Production StandardJIS G 3444
Manufacturing ProcessesERW (Electric Resistance Welding)
SSAW (Spirally Submerged Arc Welding)
LSAW (Longitudinal Submerged Arc Welding)
SMLS (Hot Finished / Cold Drawn Seamless)
Outside Diameter21.7-1016.0mm
Wall Thickness2.0-22mm
Pipe Length3-18m
Steel GradeSTK290STK 500
STK 400STK 540
STK 490
Corrosion PreventionLacquer, Varnish, Oiling, Galvanizing
End ProcessesSquare Cut, Bevelling, Threading, Grooving , Shouldering
Further ProcessingWelding, Bending, Hole Drilling, Punching, Swaging, Tapering, Flaring, Expanding

JIS G3444 Dimension Table


Our JIS G3444 tubes come in a range of dimensions to suit diverse requirements. The outer diameter ranges from 33.4mm to 660mm, while the wall thickness varies between 2.1mm and 22mm. The tubes can be customized to lengths between 0.8m and 18m, ensuring they fit seamlessly into any project. With such a wide range of dimensions, our clients can be assured of finding the perfect tube size for their needs.

Outside Diameter mmWall Thickness mm

Chemical Requirements of JIS G3444

The chemical composition of our JIS G3444 tubes is meticulously controlled to ensure they meet the standard’s requirements. For instance, the STK400 grade has a maximum carbon content of 0.25% and a maximum phosphorus and sulfur content of 0.040%. The STK490 grade, on the other hand, has a maximum carbon content of 0.18%, silicon content of 0.55%, and manganese content of 1.50%. These precise chemical compositions ensure the tubes’ strength and durability.

Symbol of GradeCSiMnPS
STK2900.050 max.0.050 max.
STK4000.25 max.0.040 max.0.040 max.
STK4900.18 max.0.55 max.1.65 max.0.035 max.0.035 max.
STK5000.24 max.0.35 max.0.30 to 1.300.040 max.0.040 max.
STK5400.23 max.0.55 max.1.50 max.0.040 max.0.040 max.

Mechanical Requirements of JIS G3444

Our JIS G3444 tubes are designed to meet specific mechanical properties. The STK400 grade has a minimum tensile strength of 400 MPa and a minimum yield strength of 245 MPa, with an elongation percentage of 23%. The STK490 grade boasts a minimum tensile strength of 490 MPa, a minimum yield strength of 325 MPa, and an elongation percentage of 23%. These mechanical properties ensure the tubes can withstand various stresses and strains, making them ideal for structural applications.

Symbol of GradeTensile StrengthN/mm2Yield Point or Proof StressN/mm2Weld Tensile StrengthN/mm2Flattening ResistanceBendability
Distance Between Flat Plates(H)Bending AngleInside Radius
Applicable Outside Diameter
All Outside DiametersAll Outside DiametersAll Outside DiametersAll Outside Diameters50 mm or under
STK290290 min.290 min.2/3 D90°6 D
STK400400 min.235 min.400 min.2/3 D90°6 D
STK490490 min.315 min.490 min.7/8 D90°6 D
STK500500 min.355 min.500 min.7/8 D90°6 D
STK540540 min.390 min.540 min.7/8 D90°6 D
NOTE 1 In this table,D stands for the outside diameter of tube.

Steel Grades in JIS G3444

We offer JIS G3444 tubes in various steel grades, including STK290, STK400, STK490, STK500, and STK540. Each grade is tailored to specific applications, ensuring optimal performance. Whether you’re looking for tubes with high tensile strength or those suitable for heavy-duty applications, our range of steel grades ensures you find the perfect match for your project.

Production Tolerance ofJIS G3444

Table Tolerances on wall thickness
Seamless steel tubeOther than seamless steel tube
Class 1Under 4mm +0.6mm -0.5mm 4mm or over +15% -12.5%Under 4mm +0.6mm -0.5mm 4mm or over +15% -12.5% Under 12mm -12.5% 12mm or over +15% -1.5mm
Class 2Under 3mm[0.3% 3mm or over [10%Under 3mm [0.3% 3mm or over [10% Under 12mm[10% 12mm or over +10% -1.2mm

Reference Resource

Our Advantages

  1. Over 25 years of experience in pipeline production and installation.
  2. Comprehensive inspection equipment.
  3. Independent product serial numbers for traceability.
  4. Advanced production equipment – Seamer high-frequency welding machine from the United States.
  5. Complete qualifications – API 5L/API 5CT/FM/UL fire pipe certification, etc.
  6. Wide range of products – independently developed solar torque tubes, highly favored in the European market.
  7. Customers spread across the globe.
  8. Excellent after-sales service and sense of responsibility.

Application Scenarios

Our steel pipes are engineered to withstand high temperatures, corrosive environments, and varying pressures, ensuring reliability and safety in the complex petrochemical processes. 

Whether it’s transferring crude oil, natural gas, or chemical intermediates, the robustness and versatility of steel pipes make them indispensable components of the plant’s infrastructure, contributing to efficient production and maintenance of stringent safety standards.

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