Lifting Clamps for Steel Plates, Beams and Drums

Technical guide to lifting clamps under EN 13155 and ASME B30.20: eccentric cam mechanics, vertical vs horizontal plate handling, 10% minimum load thresholds, and surface hardness limits.

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In steel fabrication yards, shipyard dry docks, and port logistics terminals, lifting large structural steel plates, I-beams, and chemical drums presents unique rigging challenges. These loads frequently lack pre-drilled lifting holes, pad eyes, or attachment lugs. Welded temporary lifting lugs require costly non-destructive testing and grinding after use. Under these conditions, engineered mechanical **Lifting Clamps** provide an indispensable, rapid, and secure material handling solution. Governed by international standards such as **EN 13155 (Cranes – Safety – Non-fixed load lifting attachments)** and **ASME B30.20 (Below-the-Hook Lifting Devices)**, plate and beam clamps rely on precision mechanical cam-locking forces. Riggers and crane operators must understand clamping mechanics, surface hardness limitations, minimum load requirements, and mandatory safety latch protocols. ## Clamping Mechanics: How Friction Multiplies with Load A common misconception is that lifting clamps grip solely through spring tension. In reality, modern lifting clamps operate on a self-locking eccentric cam mechanism: - When a steel plate is inserted into the clamp jaw, a spring-actuated cam mechanism engages the surface. - As the crane applies upward tensile force on the lifting eye, the internal linkage forces a hardened, serrated alloy steel cam into the plate face. - The gripping force generated by the cam is directly proportional to the hoisted load weight: **the heavier the load, the ti...