Lifting Clamps Guide: Types, Ratings & How to Choose

Steel plates, structural beams, and pipe sections present a common challenge on job sites: they often lack attachment points for slings or hooks. A lifting clamp solves that problem by gripping the material directly, creating a secure connection between the load and the hoisting equipment without requiring drilled holes, welded lugs, or wrapping slings around the piece.

Selecting the right lifting clamp depends entirely on the material being handled, the orientation of the lift, the thickness of the workpiece, and the surface condition. A vertical plate clamp, a horizontal plate clamp, and a beam clamp each serve a different mechanical purpose. Using the wrong type for the application compromises both the grip and the load.

This technical guide explains the main types of lifting clamps, how their ratings work, and what to evaluate when selecting one for a given application.

Safety & Use: Ratings and examples here serve as safety awareness. Final lift plans and gear selection must follow applicable standards, manufacturer data, and engineered lift planning where required.

What Are Lifting Clamps?

A lifting clamp is a grip-type below-the-hook device that mechanically fastens onto a material-such as a steel plate, beam flange, or pipe wall-to create a lifting point. The clamp body connects to the hoisting equipment above, while the jaw mechanism grips the workpiece below.

What makes lifting clamps distinct from other rigging hardware is that the grip force acts as the actual connection. There is no separate fastener, no wrapping, and no threading through an opening. The clamp jaw contacts the material surface directly. The clamping force generates either from a cam mechanism that tightens under load or from a screw-driven compression system.

The grip quality depends heavily on several factors: the material thickness relative to the clamp's jaw range, the hardness and surface condition of the workpiece (mill scale, paint, rust, oil), and the orientation of the lift. Each of these variables dictates whether the clamp can develop and maintain adequate holding force throughout the operation.

ASME B30.20 (Below-the-Hook Lifting Devices, 2025 edition) covers lifting clamps in a dedicated chapter that includes requirements for marking, manufacturing, inspection, testing, maintenance, and operation. OSHA 29 CFR 1926.251 also addresses rigging equipment for material handling in construction, including specific provisions for custom lifting accessories.

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Types of Lifting Clamps

Manufacturers design lifting clamps for specific material shapes and lift orientations. Choosing the correct type means perfectly matching the clamp to both the workpiece geometry and the direction of the pull.

A vertical plate clamp grips the edge of a steel plate and lifts it in an upright (vertical) orientation. These rank among the most widely used lifting clamps in steel fabrication, shipbuilding, and structural work.

Vertical Plate Clamps

Vertical plate clamps typically utilize a cam-operated jaw system. When the load applies tension, the weight of the plate drives the cam tighter against the material, increasing the clamping force proportionally to the load. This self-locking mechanism means the grip grows stronger as the load gets heavier-up to the clamp's rated capacity.

Most vertical plate clamps feature a safety latch that locks the clamp in position once engaged. The latch keeps the cam pre-tensioned on the material before the hoisting force takes over, stopping the clamp from slipping off during the initial pick.

Holloway Houston supplies the , available in capacities from 0.5 through 30 metric tons with jaw openings up to 155 mm. The IPU10 features a hinged hoisting eye that permits the clamp to engage the load from any direction and work seamlessly with multi-leg sling arrangements.

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Horizontal Plate Clamps

A horizontal plate clamp lifts steel plates, sheets, or similar flat materials while keeping them in a horizontal (flat) orientation. Unlike vertical clamps that bite a plate edge, horizontal clamps grip the flat face of the material.

Riggers typically use horizontal plate clamps in pairs or sets. A single clamp on one edge of a plate would immediately cause it to tilt and slip. Using two or more clamps spaced along the length of the plate distributes the load evenly and keeps the material level during the lift.

The covers capacities from 0.75 through 25 tons per pair, with jaw openings up to 60 mm. These clamps handle lifting and transferring material in the horizontal position, including thin sheet stock and other materials that bend or sag when lifted from a single point.

For applications where the workpiece surface cannot sustain marks or damage, the handles 0.5 through 2 metric ton capacities. The non-marring jaw design permits the handling of finished, polished, or coated surfaces.

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Beam Clamps

Beam clamps grip structural steel beams-H-beams, I-beams, and wide-flange sections-directly by the flange. They serve two primary functions in rigging: lifting and transferring beams, and acting as temporary rigging attachment points on installed structural steel.

The jaw geometry of a beam clamp differs entirely from a plate clamp. Beam clamp jaws wrap around a beam flange, and the clamp body keeps the beam in its intended orientation (typically flange-vertical) during the lift.

The handles lifting, transferring, and stacking H-beams. A ring-center hoist eye on the IPBSNZ allows the beam flange to remain vertical during handling-a feature that matters heavily when crews need to set beams directly into position without reorientation. Alternatively, the specifically targets the transfer and stacking of steel beams, available in 1, 2, and 4-ton capacities with grip ranges up to 1.13 inches.

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Pipe Lifting Clamps

Pipe lifting clamps tackle cylindrical loads-steel pipe, tubing, and round sections. The jaw shape mirrors the pipe circumference, and the clamping mechanism accounts for the curved surface geometry. Pipe clamps may use a friction grip, a mechanical locking system, or a combination of both.

Specialty Clamps

Beyond the core types, specialty clamps address specific industry applications:

Positioning/Screw Clamps: Use a screw-driven mechanism for controlled clamping force, suited for applications where a cam lock is inappropriate.
Barrier Grab Clamps: Designed for specific structural shapes encountered in highway, rail, and construction barrier work.
Rail Clamps: Purpose-built for railroad rail and similar asymmetric profiles.

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How Lifting Clamp Ratings Work

Every lifting clamp carries a Working Load Limit (WLL)-the maximum load the clamp is rated to handle under controlled conditions.

WLL and Jaw Opening

A lifting clamp's WLL ties directly to its jaw opening range. The clamp is rated strictly for a specific range of material thicknesses. If the workpiece is thinner than the minimum jaw opening or thicker than the maximum, the clamp cannot develop its full rated grip and must not be used.

Crosby permanently stamps the WLL and jaw opening on every clamp body, along with the CrosbyIP logo, a unique serial number, and the proof load test date. This marking practice fully aligns with ASME B30.20 requirements for below-the-hook lifting device identification.

Proof Testing

Crosby lifting clamps are individually proof-tested to 2 times the Working Load Limit, with a test certificate issued for each unit. This manufacturer standard exceeds the OSHA construction requirement under 29 CFR 1926.251, which mandates custom lifting accessories be proof-tested to 125 percent of their rated load prior to use.

The proof test confirms the structural integrity of the individual clamp, which is why each unit carries its own serial number and test date rather than relying on a batch certification.

Surface Condition and Grip

WLL ratings assume highly specific surface conditions. Rust, mill scale, paint, oil, and moisture heavily reduce the friction between the clamp jaw and the workpiece. Manufacturer documentation dictates the exact surface conditions under which the rated WLL applies.

Some clamp jaws feature hardened teeth to increase grip on steel surfaces. Non-marring clamp jaws trade some gripping force for surface protection, which is why non-marring models typically carry lower WLL ratings than standard-jaw clamps of the identical size.

Minimum Load Requirement

An often-overlooked specification is the minimum load requirement. Per Crosby product documentation, the minimum load for Crosby clamps is 10% of the rated capacity. A cam-locking clamp relies entirely on load weight to drive the clamping mechanism. If the load is too light, the cam fails to develop sufficient clamping force.

Lifting Clamp Inspection

ASME B30.20 (2025 edition) establishes three inspection classifications for clamps used as below-the-hook lifting devices: every-lift inspections, frequent inspections, and periodic inspections.

Inspection Personnel

Under the ASME B30.20 framework, a designated person performs the visual inspections. When they identify deficiencies, a qualified person examines the findings and determines whether they constitute a hazard and what additional steps are necessary.

What to Look For

Removal-from-service indicators for lifting clamps include:

Cracksin the clamp body, jaw, or pivot points.
Deformation of the jaw, body, or hoisting eye.
Worn jaw teeth or pads that reduce grip effectiveness.
Damaged or inoperative cam/spring mechanism that prevents proper locking.
Excessive corrosion affecting the clamp's structural integrity or jaw function.
Heat damage indicators such as temper discoloration or warping.
Loose or missing fasteners including pivot pins and latch components.
Illegible markings-if the WLL, serial number, or jaw opening cannot be read, the clamp cannot be verified for the application.

Maintenance Program

ASME B30.20 mandates a maintenance program based on the manufacturer's recommendations. Crosby clamps ship with a user manual detailing maintenance intervals. Furthermore, Crosby equips their clamps with programmable RFID chips, assisting in automated, accurate inspection tracking across a fleet of hardware.

Choosing the Right Lifting Clamp

Selecting a lifting clamp involves matching several variables to the application.

Material Type and Shape: A plate clamp jaw will not grip a beam flange properly, and a beam clamp will not work on flat plate. Start with the workpiece shape.
Lift Orientation: Whether the material will be lifted vertically, horizontally, or turned during the lift determines the clamp type.
Material Thickness and Jaw Range: The workpiece thickness must fall within the clamp's rated jaw opening range.
Surface Condition: Clean, dry, bare steel provides the best grip surface. Painted, oily, corroded, or wet surfaces reduce friction and may require a different clamp type or a derating per the manufacturer's guidance.
Load Weight and WLL: The load weight determines the minimum WLL needed. Remember the minimum load requirement (10% of rated capacity) to guarantee proper cam engagement.

Shop Lifting Clamps at Holloway Houston

Looking for the right lifting clamp? Holloway Houston stocks the full range of Crosby and Crosby Clamp-Co clamps vertical plate clamps, horizontal plate clamps, beam clamps, pipe clamps, and specialty non-marring models.

Need help matching a clamp to your specific material thickness or rigging application? or call our hardware specialists at (713) 675-3900.

Related Rigging Hardware Resources

Related rigging hardware overview.
Related attachment point hardware for below-the-hook assemblies.

April 1, 2026 | Categories: Products | By: Holloway Team

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The content provided is for general informational purposes only and is not a substitute for professional advice. Holloway Houston, Inc. is not responsible for any actions taken based on this information.

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