12.1 Below-the-Hook Lifting Devices
Key Takeaways
- Structural lifting beams and spreaders control attachment spacing and sling angles; use only rated, tagged devices hung and loaded per the manufacturer’s design.
- Plate clamps are orientation-specific (vertical vs horizontal); jaws and locks must fully engage, and plate thickness must fall within the clamp’s marked range.
- Beam/girder clamps transfer load into structural flanges only when sized, seated, and used within capacity and manufacturer limits.
- Never improvise below-the-hook devices from non-rated steel, scrap beams, or shop-fabricated bars without design and identification—use only engineered, tagged BTH gear.
12.1 Below-the-Hook Lifting Devices
Quick Answer: Use rated, tagged below-the-hook (BTH) lifting devices—lifting beams, spreaders, plate clamps, and beam/girder clamps—to control attachment spacing, sling angles, and grip geometry that plain slings cannot provide. Match clamp orientation (vertical vs horizontal) and plate thickness range, confirm lock engagement, and never improvise BTH gear from non-rated steel or scrap shop iron.
Execution of Rigging Activity is about 42% of the NCCCO Rigger Level I written exam. Inspection chapters teach you when BTH devices fail criteria (ASME B30.20 concepts). This section focuses on correct use: when to hang a spreader, how plate clamps must grip, how beam clamps seat on flanges, and why field-built “beams” from scrap are exam-wrong and jobsite-forbidden.
Level I work assumes load weight, center of gravity, and configuration are known or provided. You still must choose the right device, connect it correctly, stay inside working load limit (WLL) and geometry limits, and refuse gear that is missing tags, locks, or manufacturer instructions.
What “Below-the-Hook” Means in Execution
A below-the-hook lifting device is equipment that attaches to a hoist or crane hook (or to a master link on the hook) to interface with the load. Slings, shackles, and hooks are related hardware; BTH devices add structure or grip so the load can be handled safely.
| BTH type | Primary execution purpose | Typical Level I use case |
|---|---|---|
| Lifting beam | Central hook pick with multiple lower attachment points; can introduce bending in the beam | Loads needing fixed lower spacing under a single upper pick |
| Spreader beam / frame | Holds lower attachment points apart so sling legs stay near vertical | Long loads, multiple pick points, reduced inward sling angle |
| Plate clamp | Mechanical grip on plate edge or face | Steel plate handling without permanent lift lugs |
| Beam / girder clamp | Clamps to a structural flange for temporary pick or anchor per design | Moving beams, temporary attachment where allowed |
Inspection details (welds, jaw wear, missing tags) belong with B30.20 frequent inspection. Execution asks: Is this the right device for this load geometry, and is it hung and locked correctly?
Structural Lifting Beams and Spreaders
Why They Exist
When two sling legs attach far apart on a long load and meet at one crane hook, sling angle drops and leg tension rises. A spreader or lifting beam keeps lower attachment points at a designed spacing so legs remain closer to vertical (or at designed angles), reducing side-load on pick points and keeping leg load within plan.
- Spreader beams typically place the crane connection so the main member works primarily in compression (strut between lower points) with end fittings for slings or shackles.
- Lifting beams often hang from a central (or designed) upper pick and may see bending as they support spaced lower points.
- Frames and multi-point beams combine spacing with multiple lower connections for designed CG alignment.
You do not redesign the beam in the field. You use the device as rated and labeled, with lower attachments at the provided pad eyes, shackles, or holes only—not drilled freehand, not chained around the web midspan unless the manufacturer explicitly rates that method.
When to Use Structural BTH Devices
Use a rated lifting beam or spreader when the lift plan or known configuration requires:
- Controlled attachment spacing so multiple lift points share load as designed.
- Sling-angle control—keeping legs near the angles used for capacity and hardware selection.
- Clearance or headroom management when a long multi-leg bridle alone would create unacceptable angles or interference.
- Protection of the load by avoiding crushing compression from steep multi-leg angles on fragile assemblies (per plan).
How-To: Hang and Connect a Spreader or Lifting Beam
- Verify identification: Rated capacity, serial/ID as required, manufacturer data, and any configuration notes (e.g., which holes may be used). Missing or illegible rating → do not use.
- Match capacity to the load: Device WLL (and any lower fittings) must meet or exceed the load and the forces from the planned geometry—not “looks beefy.”
- Inspect structure before hang: Bent members, cracked welds, elongated holes, damaged pad eyes, missing bolts → remove from service (inspection domain, execution refusal).
- Connect upper end: Seat the beam’s upper master link, shackle, or designed connection fully in the bowl of the crane hook; use latches and hardware per practice; never tip-load the hook.
- Connect lower ends only at rated points: Shackles pin correctly; sling eyes seated; no improvised wraps on unrated sections of the beam.
- Align to CG: Lower attachment pattern should match the known center of gravity and lift plan so the beam hangs level (or as designed) under load.
- Test lift carefully: Raise slightly, check level and security, then proceed. Stop if the beam racks, one end lifts first unexpectedly, or connections shift.
| Execution check | Accept | Refuse / correct |
|---|---|---|
| Tag / capacity | Legible, adequate for load and config | Missing, painted over, capacity unknown |
| Lower points | Only manufacturer holes/pad eyes | Chain choked mid-web “because it fits” |
| Upper connection | In hook bowl, hardware correct | Tip of hook, open shackle pin, sideways load |
| Geometry | Spacing matches plan / CG | One side short, beam canted hard |
Plate Clamps: Vertical vs Horizontal
Plate clamps grip steel plate so you can lift without welded lugs. They are not universal tongs. Orientation, thickness range, and lock function are execution fundamentals.
Vertical vs Horizontal Clamps
| Feature | Vertical plate clamp | Horizontal plate clamp |
|---|---|---|
| Typical lift | Plate lifted on edge (vertical plane) | Plate lifted flat (horizontal plane), often in pairs/sets |
| Grip orientation | Designed for vertical lift loading | Designed for horizontal plate handling |
| Common mistake | Using a vertical clamp as a horizontal tool | Using horizontal clamps alone when vertical edge lift is required |
| Exam rule | Match clamp type/orientation to how the plate will hang | Follow manufacturer pairing and angle rules for multi-clamp sets |
Never assume a clamp marked for one orientation is safe for the other. Manufacturer literature and markings control selection.
Thickness Range
Every lifting plate clamp has a minimum and maximum plate thickness (or jaw opening range). Execution rules:
- Plate thinner than minimum may not allow the cam/jaw to develop rated grip—slip risk.
- Plate thicker than maximum may prevent full lock or overload the mechanism—do not force.
- Measure plate thickness at the grip location (not only at a random edge burr).
- Surface condition matters: oil, scale, paint thickness, and tapered edges can reduce grip; follow manufacturer limits for surface and hardness.
Lock Engagement
Many clamps use a locking lever, cam, or spring-assisted lock so the jaw stays engaged until intentionally released.
How-To: Seat a plate clamp
- Confirm orientation (vertical/horizontal) matches the planned plate attitude.
- Confirm capacity ≥ plate weight (and share of weight for multi-clamp lifts).
- Confirm plate thickness is within marked range.
- Open jaws fully; seat clamp so the plate fills the jaw as designed—full bite, not on a corner only unless rated for that geometry.
- Close and lock the mechanism; verify the lock is fully engaged (lever home, indicator if provided).
- Connect the clamp’s lifting eye to the sling/shackle without side-loading the eye beyond design.
- Test lift a few inches; watch for slip. If the plate creeps, lower, re-seat, or change method—do not “hope it bites” at height.
- Never use a clamp with a broken lock, worn jaws, or missing safety latch as a temporary grab.
Multi-clamp horizontal lifts: Use the number and spacing the plan or manufacturer requires so clamps share load and the plate remains stable. Uneven spacing or single-clamp horizontal lifts of large plates are common failure setups.
Beam and Girder Clamps
Beam (girder) clamps attach to the flange of an I-beam or similar section. Some are used as temporary hoist support points; others help handle beams as loads. Level I execution points:
- Size the clamp to the flange width and thickness within manufacturer tables—not by eye.
- Seat fully on the flange; do not hang from the web tip or partially on paint ridges.
- Respect capacity and load direction. Many clamps are rated for specific orientations (e.g., centered load under the clamp). Side loading or using a clamp as a universal shackle substitute is unsafe.
- Tighten/adjust per instructions (screw mechanisms, locking collars). Hand-tight “until it feels snug” is not a rating method if torque or engagement marks are specified.
- Inspect threads, jaws, and body before use; damaged clamps are out of service.
When a beam clamp is used as a hoist suspension point, additional site rules, capacity of the supporting structure, and qualified person decisions apply—Level I does not invent structural capacity for building steel.
Never Improvise BTH Devices from Non-Rated Steel
Exam and field rule: only engineered, identified lifting devices carry overhead loads as BTH gear.
| Improvised practice | Why it fails |
|---|---|
| Scrap H-beam with burned holes as a “spreader” | Unknown steel, no WLL, stress risers at torch cuts, no design for bending/compression |
| Pipe or channel with chain wrapped ends | Not a rated attachment geometry; slip and crushing |
| Shop-welded lugs on random bar stock | Welds and base metal not proven for lifting service |
| “We’ve used this I-beam for years” without tag | History is not a capacity rating |
If a job needs a spreader, obtain a manufactured/rated device (or an engineered lift plan with certified temporary devices). Level I execution is selection and correct connection—not fabrication of unrated lifting beams.
Integration with Hooks, Slings, and the Lift Plan
BTH devices sit in the load path: crane → hook → BTH device → lower gear → load.
- Keep the weakest link above the load weight for the configuration in use.
- Do not overcrowd the crane hook with multiple eyes that force tip loading; use a master link or properly sized connection.
- After the lift, land the load, unload the device, then disconnect clamps carefully—do not kick locks open under residual tension.
- Store and protect BTH gear so tags remain legible and mechanisms stay free of grit (stowage details appear in post-lift execution chapters).
Exam Focus Summary
| Topic | Level I takeaway |
|---|---|
| Lifting beams / spreaders | Control spacing and sling angles; use only rated points and capacity |
| Plate clamps | Orientation + thickness range + full lock engagement |
| Beam/girder clamps | Flange fit, capacity, correct load direction |
| Improvised steel | Never substitute for tagged BTH devices |
| vs Inspection | Inspection rejects damage; execution uses correct type correctly |
Master these distinctions and you protect both the written domain score and the people under the hook.
A long steel assembly has two designed lift points far apart. Using two short sling legs from those points straight to one crane hook creates a very low included angle. What is the primary execution reason to introduce a rated spreader or lifting beam?
A vertical plate clamp is selected for a steel plate. Which condition is required before applying lift tension?
A crew wants to lift with a shop-cut length of I-beam that has torch-burned holes near each end and no manufacturer rating. What is the correct Level I decision?
When connecting a rated lifting beam to the crane hook, how should the upper connection be seated?