Girder Clamp (Gravlock SK Fitting) – Secure Scaffold Attachment to Steel I-Beams
The Girder Clamp is a robust, drop-forged scaffolding component designed to securely attach 48.3mm diameter galvanised scaffold tubes to steel I-beams or girders. Commonly referred to as a Gravlock SK fitting or steel beam clip, this essential fitting enables stable connections in steel-framed structures, allowing scaffold poles to be fixed horizontally to beams for installing safety handrails, access platforms, or continuing scaffold builds in environments such as warehouses, factories, and construction sites.
Always used in pairs for each upright tube, it is engineered for I-beams up to 44mm thick and provides a reliable solution where traditional scaffold bases aren’t feasible.
Key Features & Benefits
- Drop-forged steel provides strong, durable construction.
- Supports up to 30kN for safe hanging applications.
- Requires a minimum tightening torque of 54 Nm for a secure grip.
- Meets AS 1576.1 scaffolding standards.
- Galvanised finish protects against corrosion outdoors.
- Suitable for professional scaffold use in large steel warehouse projects, including handrails.
- Made with sustainably sourced materials for reliability and safety.
- Lightweight at 1.56kg per unit for easy handling.
- Complies with BS 2482:2009 for assured performance.
Product Specifications
| Specification | Details |
|---|---|
| Product Name | Girder Clamp (Gravlock SK Fitting) |
| Condition | New |
| Tube Size Compatibility | 48.3mm diameter scaffold tubes |
| Beam Compatibility | I-beams up to 44mm thick |
| Material | Drop-forged steel |
| Weight (approx.) | 1.56kg |
| Safe Working Load | 30kN (hanging) |
| Minimum Torque | 54Nm |
| Standards Compliance | AS 1576.1, BS 2482:2009 |
| Usage | Load-bearing (in pairs) |
Frequently Asked Questions (FAQs)
How does the girder clamp compare to other beam attachment options?
Girder clamp vs alternatives comparison.
Feature / Specification | Girder Clamp (Gravlock SK / Fixed) | Traditional RSJ Clamp (Graded Sizes) | Swivel Beam Clamp (Angled Variant) |
Connection Angle | Fixed 90° (right-angle) | Fixed 90° | Adjustable (any angle, swivel) |
Max Flange Thickness | Up to 44mm (some specs 45mm) | Varies by size: Size 1 ≤19mm, Size 2 19–38mm, Size 3 38–57mm | Up to 44–45mm (similar to fixed) |
Material & Construction | Drop-forged steel (high strength) | Often pressed or drop-forged (varies) | Drop-forged steel |
Safe Working Load (per pair, typical) | 30kN (hanging/vertical) | 6.25–15kN (lower, slip resistance focused) | 6.25–15kN (reduced due to swivel) |
Slip Resistance Along Beam | Typically 6.25–15kN (with 54Nm torque) | Similar range (6.25kN common) | Similarly, the swivel may reduce grip |
Best Applications | Standard I-beams, warehouse handrails, platforms, and high-load hanging | Variable/thicker flanges, basic attachments | Angled bracing, complex/non-90° setups, ties |
Must Use In Pairs? | Yes (essential for balance) | Yes | Yes |
Standards Compliance | AS 1576.1, BS 2482:2009 | EN74 / BS1139 variants (often) | EN74 / AS 1576 variants |
Advantages | Higher load capacity, robust drop-forged durability, ideal for 90° handrail/platform installs | Handles a wider flange range with graded sizes | Flexibility for non-perpendicular connections |
Drawbacks | Limited to ≤44mm flanges, no angle adjustment | Lower SWL may require multiple sizes | Lower load capacity, potentially reduced stability at angles |
What is the recommended installation guide?
Step | Description |
1 | Position two girder clamps horizontally on the I-beam, one on each side of the intended upright position. |
2 | Insert a short scaffold tube section through the open ends of both clamps. |
3 | Attach a vertical 5ft (or required length) scaffold tube to the horizontal tube using a double coupler. |
4 | Tighten all bolts to the recommended torque of 54Nm using a scaffolding spanner. |
5 | Verify stability before loading or use. |
What is a girder clamp used for in scaffolding?
Girder clamps are designed to secure scaffold tubes to steel I-beams or girders firmly. When combined with double couplers, they’re perfect for creating safe handrails and access platforms and for extending scaffolding in warehouses and other steel-framed structures.
Is it load-bearing?
Yes, it is designed as a load-bearing fitting, with a safe working load of 30 kN when used in pairs for hanging applications. It provides secure attachment under tension or compression forces.
How does it differ from standard couplers, such as double or swivel couplers?
Unlike standard couplers that join scaffold tubes, the girder clamp is specifically engineered to grip steel beams up to 44mm thick, making it essential for attaching scaffolding to structural steel rather than for tube-to-tube connections.
What beam thickness is suitable?
It fits I-beams with a maximum flange thickness of 44mm. Always check the beam dimensions before use to ensure a proper fit.
Can it be used on other beam types or materials?
Primarily designed for standard steel I-beams. Consult a qualified scaffold engineer for non-standard applications.
How many should I use per upright tube?
Always install in pairs, one on each side of the beam, for balanced load distribution and safety.
Does it require any special tools for installation?
Standard scaffolding spanners are sufficient for tightening to the required torque of 54Nm. No specialised equipment is needed beyond basic scaffolding tools.
Is it suitable for temporary or permanent installations?
It excels in temporary scaffolding setups but is built to high standards for long-term reliability in structural applications.
Is there a swivel version of the girder clamp available?
Yes, swivel girder clamps (or swivel beam clamps) exist for angled connections (not fixed 90°). They offer flexibility for bracing or complex setups but usually have lower load capacities (e.g., 6.25–15 kN) than fixed types. For standard 90° handrail or platform attachments, stick with the fixed Gravlock version.
What happens if I over-tighten the bolts beyond 54Nm?
Over-tightening can deform the clamp, damage the beam flange, or reduce long-term grip due to material stress. Always use a calibrated spanner and stop at the minimum torque of 54Nm for optimal performance. Under-tightening risks slippage; follow the manufacturer’s guidelines to safely achieve the rated 30kN hanging load.
How do I check if the girder clamp is installed correctly and secure?
After tightening to 54 Nm, visually inspect for full flange contact, no gaps, and aligned opposing pairs. Test for stability (no wobble under light load), ensure the horizontal tube is level, and confirm the double coupler connection to the upright is firm. Periodic checks during use are essential, especially in high-vibration environments.
Can girder clamps be reused, and how long do they last?
Yes, they are reusable if undamaged (no cracks, deformation, or severe corrosion). Inspect for wear before each use, replace if galvanising is compromised, and store properly to extend lifespan. Drop-forged construction makes them highly durable for repeated professional applications.
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