Scaffolding Steel Frame System Joint Pin (Coupling Pin)

The Scaffolding Steel Frame Joint Pin (also known as a coupling pin or insert pin) is an essential connector designed to vertically link and secure stacked scaffolding frames. A standard single-bay scaffold framework assembly strictly requires 4 pieces of joint pins to connect the upper and lower frames securely.

Manufactured from high-grade Q235 carbon steel, our joint pins provide excellent shear strength to keep high-rise frame towers perfectly aligned and structurally sound. Because joint pins sit inside the main frame tubes where moisture often collects, we apply a premium Electro-Galvanized (Zinc-plated) surface treatment. This ensures long-term rust prevention and smooth assembly, making them an indispensable component for masonry, outdoor facade maintenance, and indoor decoration scaffolding systems.

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Multiple scaffolding steel frame system joint pins

Technical Specifications

Technical Category Specification Details
Product Name Scaffolding Frame Joint Pin / Coupling Pin
Material Grade Q235 Carbon Steel
Outer Diameter (OD) 35mm / 36mm (Designed to fit inside 42.4mm / 42mm Main Frames)
Wall Thickness 1.5mm, 1.8mm, 2.0mm
Standard Length 220mm – 230mm
Component Feature With Center Collar / Stopper Button
Surface Treatment Electro-Galvanized (EG) / Zinc-Plated
Standard Set Requirement 4 pieces of joint pins per scaffold frame set

Key Advantages

Precision Fit & Tolerance Control: A joint pin that is too loose will cause the scaffold tower to sway; one that is too tight will drastically slow down assembly. Our pins are manufactured with exact OD tolerances (e.g., 35mm or 36mm) to slide perfectly into the internal diameter of standard 42mm frames, ensuring a secure, wobble-free vertical connection.
Enhanced Shear Strength: The vertical load and lateral forces of a scaffolding tower exert immense pressure on the connection points. Utilizing robust Q235 steel with thicknesses up to 2.0mm, our joint pins offer exceptional shear strength to prevent buckling.
Superior Moisture Resistance: The Electro-Galvanized finish provides a smooth, zinc-plated barrier. This is critical because water can enter the scaffolding tubes during rain; the EG treatment prevents the internal pins from rusting and seizing inside the frames.
Built-in Safety Collar: Our pins feature a distinct center collar (or stopper button), ensuring the pin sits exactly halfway between the top and bottom frames. This guarantees equal load distribution and secure locking.

Product Applications

Vertical Frame Connection: Exclusively used to vertically stack Walk-Through Frames, Mason Frames, Ladder Frames, and H-Frames.
Mobile Rolling Towers: Essential for securely linking multiple frame tiers when erecting mobile access towers with caster wheels.
Exterior & Interior Construction: Provides vertical alignment for scaffolding used in painting, plastering, and heavy-duty masonry work.

Packaging & Delivery

Durable Woven Bag & Pallet Packing: Due to their small size and high density, joint pins are typically packed in heavy-duty woven bags (e.g., 50 or 100 pieces per bag) and then secured onto steel or wooden pallets. This prevents loss during transit and ensures easy unloading.
Container Consolidation: Joint pins are usually purchased alongside main frames and cross braces. We expertly consolidate these fittings within 20ft or 40ft containers to maximize your payload and minimize shipping costs.
Efficient Export Logistics: Dispatched directly from Tianjin, China. Our proximity to Xingang Port allows for rapid customs clearance and swift international maritime shipping.

Frequently Asked Questions (FAQ)

Q: How do I know which Joint Pin Outer Diameter (OD) to choose?
A: The OD of the joint pin must be slightly smaller than the Inner Diameter (ID) of your main scaffolding frame tube. For example, if your frame tube is 42mm OD with a 2.2mm thickness (ID = 37.6mm), a 35mm or 36mm OD joint pin is the perfect fit.

A: A complete single scaffolding set (1 tier) consists of 2 main frames, 2 cross braces, and 4 joint pins. You will need 4 pins for every additional tier you stack vertically.

A: Joint pins are inserted inside the frame tubes where friction is high during assembly. Paint would easily scrape off, leading to rapid rusting. The EG zinc coating is metallurgically bonded to the steel, providing a smooth, durable, and highly rust-resistant surface that outlasts painted alternatives.

A: Yes, our standard joint pins are punched with securing holes, allowing you to insert toggle pins, span pins, or cotter pins to firmly lock the upper and lower frames together against wind uplift.

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