JIS G3444 STK400 Galvanized Steel Pipe 48.3mm OD for Scaffolding System

Engineered to provide superior structural strength and safety for high-rise construction, this JIS G3444 STK400 Galvanized Steel Pipe is the international industry standard for scaffolding systems. Featuring a precise 48.3mm outer diameter, this tube is compatible with all standard scaffolding couplers, drop-forged clamps, and modular access fittings. Fabricated from premium STK400 carbon steel under strict Japanese Industrial Standards (JIS), it delivers a minimum tensile strength of 400 MPa, ensuring excellent load-bearing capacity and resistance to bending and buckling forces under extreme structural loads.
The entire pipe undergoes hot-dip galvanizing to form a thick, impact-resistant zinc cladding. This protective layer shields the steel from harsh weather, continuous outdoor exposure, and abrasive site handling, making it a highly reusable, durable, and safe asset for access scaffolding, structural shoring, and temporary construction frameworks.

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Features & Advantages

True JIS G3444 STK400 Compliance: Certified structural steel grade guaranteeing a minimum tensile strength of 400 MPa and yield strength of 235 MPa, which is critical for worker safety and municipal structural calculations.

The Scaffolding Gold Standard (48.3mm OD): Precision-engineered outer diameter ensures flawless, tight mechanical engagement with standard right-angle couplers, swivel clamps, and modular sleeve joints.

Thick Hot-Dip Galvanized Armor: Coated both internally and externally with a high-purity zinc layer (up to 500 g/m²), offering rugged resistance against moisture, concrete splashes, and mechanical scratching on busy sites.

Outstanding Structural Reusability: The high yield strength of the STK400 grade prevents localized crushing and pipe warping under heavy clamping pressures, allowing the tubes to be safely reused across hundreds of construction cycles.

Technical Specifications

Specification Item	Detailed Description
Product Name	JIS G3444 STK400 Galvanized Scaffolding Pipe
Standard Specification	JIS G3444 (Carbon steel tubes for general structural purposes)
Steel Grade	STK400 (Yield Strength ≥ 235 MPa, Tensile Strength ≥ 400 MPa)
Manufacturing Process	ERW (High-Frequency Welded) followed by Hot-Dip Galvanizing
Nominal Outer Diameter (OD)	48.3 mm (1.90 inches)
Wall Thickness (WT)	2.4 mm (Lightweight series) or 3.2 mm (Standard/Heavy-duty series) or custom
Galvanizing Standards	JIS H8641, EN ISO 1461, ASTM A123
Zinc Coating Mass	Minimum average of 350 g/m² up to 500 g/m² (approx. 50–70 microns)
Pipe Ends	Square cut, plain ends, deburred to ensure safe handling and clamp fitment
Standard Length	Standard 6.0m (20ft) or customized (e.g., 1.0m to 5.8m for modular systems)

Product Applications

High-Rise Tubular Access Scaffolding: Construction staging, bricklaying access, and high-elevation building maintenance platforms.

Modular Scaffolding Systems: Serving as structural tubes for Ringlock, Cuplock, and standard frame-and-brace scaffolding.

Civil Engineering Shoring & Formwork: Heavy-duty concrete slab support, bridge shoring towers, and tunnel formwork staging.

Refinery & Marine Access Platforms: Scaffolding setups in coastal oil refineries, shipyards, and offshore platforms requiring extreme rust resistance.

Rigorous Quality Control & Manufacturing Process

Our 48.3mm STK400 scaffolding pipes undergo a rigorous, multi-step quality assurance process to ensure structural safety:

Structural Coil Sourcing: Verifying the chemical composition (carbon, manganese, silicon) of the raw steel to guarantee that the mechanical yield and tensile strengths match the strict thresholds of the STK400 specification.

ERW Welded Seam Scarfing: Continuous roll-forming and high-frequency welding of the 48.3mm tube. Crucially, the external weld bead is trimmed completely flush (scarfed) to ensure a perfectly round surface for secure coupler attachment.

Hot-Dip Galvanizing (JIS H8641): Chemical cleaning (acid pickling and fluxing) followed by full immersion of the tubes in a molten zinc bath maintained at approximately 450°C, ensuring a thick, metallurgically bonded zinc-iron alloy layer.

Straightness & Flattening Testing: 100% straightness checking (tolerance within 1mm per meter) and flattening testing to ensure the pipes will not warp or split under extreme structural loads or clamping pressures.

Frequently Asked Questions (FAQ)

Q1: Why is the 48.3mm outer diameter critical for scaffolding pipes?

A: The 48.3mm (1.90-inch) OD is the universally accepted standard for tubular scaffolding. All standard couplers, drop-forged clamps, and joint sleeves are manufactured to fit this exact diameter. A pipe with any deviation in outer diameter will result in loose, hazardous clamping or an inability to fit the couplers on-site.

Q2: What are the structural benefits of the STK400 steel grade?

A: STK400 is a Japanese structural carbon steel grade. It possesses a minimum yield strength of 235 MPa and a tensile strength of 400 MPa. This provides high stiffness and load-bearing capacity, allowing scaffolding structures to support massive vertical loads and resist lateral wind shear without bending or collapsing.

Q3: How does hot-dip galvanizing benefit scaffolding tubes compared to pre-galvanizing?

A: Pre-galvanized pipes have a much thinner zinc layer (typically less than 20 microns) and leave the weld seam vulnerable to localized rust. Hot-dip galvanizing coats the entire pipe inside and out in a thick (50–70 micron) zinc layer. This thick metallurgical coating can withstand concrete splashes, wet storage, and the constant mechanical abrasion of clamps without exposing the raw steel.

Q4: What wall thicknesses are available for JIS G3444 STK400 scaffolding tubes?

A: The two most common and certified thicknesses are 2.4mm (widely used in Asia for lightweight access and cost efficiency) and 3.2mm (the standard for heavy-duty shoring, commercial high-rise scaffolding, and high-load industrial applications). We can manufacture both options to suit your project design.