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brief introductions

Standared:JIS G3444

Grades:STK500

Other Standards: BS EN 10210 (Europe) BS EN 10219 (Europe)
ASTM A500 (American)
GB/T 3094-2000 (China) GB/T 6728-2002 (China)
JIS G3466 (Japan)
AS 1163 (Australia)

Corner Type: Radius Corner, Sharp Angle Corner, Right Angle Corner

Application: Heavy steel structure, Aerospace Engineering, High-speed rail, Shipbuilding, For machinery, For automobiles and high-speed trains, For chemical industry and boiler, For bridge.

Outside diameter: (SHS)20*20-1200*1200mm Wall Thickness: 1.3mm-50mm

Outside diameter: (RHS)20*30-1200*1500mm Wall Thickness:1.2-50mm

Length:4m, 6m, 12m or as your required

Brand: LEFIN STEEL

Chemical Composition

CHEMICAL COMPOSITION OF JIS G3444,%MAX
GRADE	C	Si	Mn	P	S
STK 400	0.25%MAX	-	-	0.04%MAX	0.04%MAX
STK 500	0.24%MAX	0.35%MAX	0.3-1.3	0.04%MAX	0.04%MAX

Physical requirements

MECHANICAL PROPERTIES OF JIS G3444
GRADE	Tensile Strength N/mm2	Yield Point or Proof Stress N/mm2	Weld Tensile N/mm2	Flattening Resistance Strength	Bendability
	Tensile Strength N/mm2	Yield Point or Proof Stress N/mm2	Weld Tensile N/mm2	Distance between Flat Plates (H)	Bending Angle, a)	Inside Radius
	Applicable Outside Diameter
	All Outside Diameters	All Outside Diameters	All Outside Diameters	All Outside Diameters	50 mm or under
STKR 400	400min	235min	400min	2/3D	90°	6D
STKR 500	500min	355min	500min	7/8D	90°	6D

JIS G3444 STK500 SCAFFOLDING PIPE

JIS G3444 Standard overview

• JIS G3444 is a technical specification for carbon steel tubes for general structural use in the Japanese Industrial Standard (JIS), the latest version is JIS G3444:2015. The standard specifies the chemical composition, mechanical properties, dimensional tolerances, detection methods and other requirements of the steel pipe, and is suitable for construction, machinery, scaffolding and other structural purposes.
STK500, one of the material grades defined in the standard, is a high-strength carbon steel designed for load-bearing structures, especially for Scaffolding pipes.

Material characteristics

Chemical Composition
• Carbon (C) : ≤0.24%
• Silicon (Si) : ≤0.35%
• Manganese (Mn) : 0.3%-1.3%
• Phosphorus (P), sulfur (S) : both ≤0.04%.

Mechanical properties
• Tensile strength: ≥500 MPa
• Yield strength: ≥355 MPa
• Elongation (δ5) : ≥17%
• Hardness (HBS) : 123-321.
• Corrosion resistance: formed by Black Annealing (Black Annealing) oxidation layer, with a certain anti-corrosion ability.

Dimensions and tolerances

• Outer diameter range: common 48.6mm (standard scaffold tube size), other specifications can be customized to 610mm.
• Wall thickness: Typically 1.8-2.3mm, about 25% less weight than traditional scaffolding tubes (such as STK500).
• Length: Usually 5.8-6.5m, supporting fixed size cutting.
• Tolerance requirements: Outer diameter ±0.5%, wall thickness ±10%.

Application Fields

Construction scaffolding: As a temporary support structure, STK500 steel pipe significantly improves construction safety and efficiency due to its high strength and lightweight characteristics.
• Mechanical manufacturing: Used for mechanical frames, conveying systems and other load-bearing parts.
• Infrastructure: railway guardrail, bridge support and other scenes requiring weather resistance and pressure resistance.
• International projects: exported to New Zealand, Vietnam and other places for mining, water transmission and other projects.

Production and testing

• Production process: High frequency straight seam resistance welding (ERW) or seamless process, combined with black annealing treatment to optimize toughness.

• Testing standards: including X-ray inspection, ultrasonic inspection, hydraulic test, etc., to ensure compliance with JIS G3444, EN10219, API 5L and other international standards.

• Certification requirements: Japan JIS certification and EU PED, Singapore FPC and other international certifications.

Comparison with other materials

• STK500 vs. STK400/STK490:

The STK500 has a significantly higher tensile strength (500MPa) than the STK400 (400MPa) and STK490 (490MPa), which is suitable for higher load scenarios.

• With traditional scaffolding pipe: using thin wall design (1.8mm) to reduce weight, while improving toughness through heat treatment, the overall performance is better than ordinary carbon steel pipe.

JIS G3444 STK500 SCAFFOLDING PIPE

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