13.3 Hoists, Come-Alongs, Chain Falls, and Rigging Inspection Procedures

13.3 Hoists, Come-Alongs, Chain Falls, and Rigging Inspection Procedures

While mobile and tower cranes dominate open construction sites, a vast amount of heavy industrial rigging occurs in confined mechanical rooms, pipe racks, boiler bays, and structural steel frames where cranes cannot access. In these environments, craftworkers rely on portable, manually operated lifting and pulling tools: manual chain hoists (chain falls) and lever-operated hoists (come-alongs). Because these mechanical devices multiply human muscle power by factors of 20 to over 100 to 1, an operator cannot feel the immense mechanical stress building up inside the gears, pawls, and chains.

Consequently, strict operating procedures, daily pre-use inspections, and formal lift planning are paramount. Under OSHA 29 CFR 1926.251, ASME B30.16 (Overhead Underhung and Stationary Hoists), and ASME B30.21 (Lever Hoists), every piece of hoisting gear must meet rigorous mechanical safety thresholds. A cracked hook, a gouged chain link, an oil-soaked brake disc, or a missing lift plan can transform a controlled equipment installation into a catastrophic drop incident.

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1. Manual Lifting and Pulling Tools: Architecture and Operating Mechanics

1. Manual Chain Hoists (Chain Falls)

A manual chain hoist (commonly referred to in the trade as a chain fall) is a portable overhead lifting machine designed exclusively for pure vertical hoisting.

                     [ Suspension Hook ] (Upper Hook)
                             │
                      ┌──────┴──────┐
                      │ GEAR HOUSING│
                      │  Planetary  │
     Continuous       │   Gears &   │        Load Chain
     Hand Chain       │Weston Brake │     (Heat-Treated Alloy)
         │            └──────┬──────┘            │
         │                   │                   │
         │              [Pocket Wheel]           │
         │                   │                   │
         ▼                   ▼                   ▼
   (Operator Pulls)    [Idler Sheave]      [ Load Hook ]
                       (Multi-Part Line)   (Safety Latch Required)

• Operating Principle: The operator pulls a continuous, lightweight loop of hand chain. The hand chain turns a hand wheel connected to a high-reduction planetary gear train. The gear train multiplies torque and turns a precision-cast pocket wheel (load sheave), which reels in or pays out the heavy-duty alloy steel load chain.
• Mechanical Advantage: Gear ratios typically range from 20:1 to over 40:1. A worker pulling with 50 pounds of force on the hand chain can smoothly elevate a 2,000- to 4,000-pound load.
• The Weston-Style Mechanical Load Brake: The defining safety feature of a manual chain hoist is the Weston-style mechanical load brake:
  • Internal Mechanism: The brake consists of a threaded drive hub on the pinion shaft, two high-friction composite brake discs, a central ratchet wheel, and spring-loaded ratchet pawls.
  • Automatic Engagement: When the operator pulls the hand chain in the hoisting direction, the drive hub threads forward, clamping the friction discs tightly against the ratchet wheel. The entire assembly rotates together, with the ratchet pawl clicking freely over the teeth.
  • Holding the Load: The instant the operator stops pulling the hand chain, the downward gravitational pull of the suspended load attempts to turn the pocket wheel backward. This reverse torque forces the threaded drive hub to screw even tighter against the friction discs, locking them immovably against the ratchet wheel held by the pawls. The load's own weight provides the clamping force that holds the brake locked!
  • Controlled Lowering: When pulling the hand chain in the reverse (lowering) direction, the drive hub is backed off the friction discs just enough to slip against the brake surface. The load descends only as fast as the operator actively pulls the chain. The moment the operator stops pulling, the brake re-clamps instantly.
• Load Chain vs. Hand Chain Distinction: Hand chain is lightweight, unrated, zinc-plated steel intended solely for human hands. Load chain is high-strength, heat-treated Grade 80 or Grade 100 alloy steel engineered specifically for cyclic overhead tensile loading. Hand chain must never be used to bear load, and load chain must never be spliced or repaired with non-rated hardware.

2. Lever-Operated Hoists (Come-Alongs)

A lever-operated hoist (universally called a come-along in the trades) uses a ratcheting hand lever to pull, tension, or hoist loads over short distances.

      [ Anchorage Hook ] ──[ Housing with Ratchet & Dual Pawls ]── [ Reversing Lever ]
                                     │                                  │
                           [ Load Chain / Wire Rope ]          [ Operating Handle ]
                                     │                         (Engineered to bend
                                     ▼                           before overloading!)
                               [ Load Hook ]

• Operating Principle: The operator rocks a ratcheting lever handle back and forth. A drive pawl engages the teeth of a hardened ratchet wheel, rotating it one notch per stroke. A separate spring-loaded holding pawl (stop pawl) prevents the ratchet from reversing when the handle is returned on the backstroke.
• Directional Selector: A three-position toggle switch on the handle selects UP / LIFT (hoisting or tensioning), DOWN / LOWER (controlled mechanical release notch-by-notch), and FREE-CHAIN / NEUTRAL (disengages pawls for rapid manual payout of slack chain under zero load).
• Link Chain vs. Wire Rope Models:
  • Link Chain Lever Hoists: Utilize heavy alloy steel chain; preferred in heavy industrial rigging, steel erection, boiler maintenance, and pipe alignment due to rugged impact and abrasion resistance.
  • Wire Rope Come-Alongs: Utilize flexible aircraft-grade steel cable wrapped on a small drum; preferred for light electrical utility pulling, fence tensioning, and light equipment positioning.
• Primary Craft Applications: While chain falls are used almost exclusively for vertical overhead lifting, come-alongs excel in horizontal pulling and drifting:
  • Pulling structural steel columns into plumb alignment before bolting.
  • Drifting heavy machinery horizontally across floors or equipment pads.
  • Aligning heavy flanged pipe joints for bolt-up.
  • Securing heavy mobile equipment on transport flatbeds.

The Cardinal Safety Rule: The Cheater Pipe Prohibition

CRITICAL RIGGING & HOIST SAFETY DIRECTIVE: Riggers must NEVER slip a cheater pipe, conduit, or structural sleeve over the lever handle of a come-along to gain extra leverage.

• The Field Trap: When a load resists movement, workers frequently slide a 3-foot piece of scaffold tubing or rigid conduit over the handle, multiplying their pulling leverage.
• The Mechanical Hazard: Manufacturers design the length of a come-along handle so that an average worker pulling with normal force (50 to 85 pounds) cannot exceed the rated Working Load Limit of the hoist. Crucially, the handle itself acts as an engineered mechanical safety fuse: under severe overload, the handle will visibly bend and deform before internal ratchet teeth, pawls, or chains fracture.
• Catastrophic Failure: Slipping a cheater pipe over the handle multiplies leverage, overrides this built-in warning fuse, overstresses the ratchet teeth and pawls, and can cause the ratchet mechanism or load chain to fail catastrophically and violently under tension.

The Free-Chaining Safety Mandate

The free-chaining (neutral) mechanism disengages the internal pawls to allow quick manual pull-through of slack chain. Riggers must NEVER attempt to engage free-chain mode while the hoist is holding tension. Free-chaining must be operated exclusively under ZERO LOAD. Engaging neutral under tension will drop the load instantly.

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2. Comprehensive Rigging Inspection and Rejection Criteria

Under OSHA 29 CFR 1926.251, ASME B30.16, ASME B30.21, and ASME B30.10, all hoisting and rigging gear must undergo two tiers of inspection: frequent inspection (a visual check performed daily before every shift by the operator or rigger) and periodic inspection (a documented, detailed examination conducted by a certified Qualified Inspector at intervals based on service severity).

                     MANDATORY HOOK REJECTION THRESHOLDS (ASME B30.10)
                     
                              [ Eye / Shank ]
                                    │
                                ┌───┴───┐
                     Cracks or  │       │  Twist > 10°
                     Gouges ───►│       │◄── from unbent plane = REJECT
                                │       │
                                └───┬───┘
                         Missing    │
                         Safety ───►│
                         Latch      │   Throat Opening Increase > 5%
                         = REJECT   │   (Max 1/4 inch / 6 mm) = REJECT
                                    │   ◄────────────────────────►
                                   /     \
                                  │  [O]  │
                                   \_____/
                                      ▲
                                      │ Bowl / Saddle Wear > 10% = REJECT

1. Load Chain Rejection Criteria (ASME B30.16 & B30.21)

A hoist load chain must be immediately removed from service, tagged out, and destroyed if ANY of the following defects exist:

1. Link Elongation / Stretch: Excessive tensile stress or shock loading stretches chain links longitudinally. As links stretch, their pitch changes, causing them to bind or jump in the pocket wheel. Any overall chain stretch exceeding 1.5% to 2.5% of original gauge length (or any chain where links bind or fail to seat smoothly in the sprocket) mandates immediate condemnation.
2. Caliper Wear: Inter-link contact points (the bearing crowns and reach bowls) experience severe friction. Measure link wire diameter with a vernier caliper. If wear exceeds 10% of nominal link wire diameter, the chain must be rejected.
3. Mechanical Gouges and Nicks: Deep gouges, cuts, or notches that reduce cross-sectional area or create stress risers.
4. Twisted, Bent, or Deformed Links: Any permanent twist, bend, or deformation from side-loading or rigging over an unsoftened edge.
5. Weld Spatter and Arc Strikes: Heat from cutting torches or arc strikes anneals the alloy steel, causing localized embrittlement and premature failure.
6. Corrosion and Lack of Lubrication: Heavy pitting, rust scaling, or stiff frozen links that do not articulate freely.

2. Hook Rejection Criteria (ASME B30.10)

Hooks on hoists, slings, and crane blocks must be condemned immediately if they exhibit:

• Throat Opening Increase: Any permanent increase in the throat opening exceeding 5% (not to exceed 1/4 inch / 6 mm) beyond factory blueprint dimensions.
• Hook Twist: Any rotational twist exceeding 10 degrees from the original unbent plane of the hook body.
• Saddle / Bowl Wear: Wear exceeding 10% of original cross-sectional thickness in the load-bearing saddle.
• Cracks, Gouges, or Sharp Notches: Any visible surface crack or deep gouge requires immediate destruction. Welding, brazing, heating, or grinding hooks to repair damage is STRICTLY PROHIBITED.
• Damaged or Missing Safety Latches: A hook must have a functional, spring-loaded safety latch that bridges the throat opening. If the latch is missing, bent, or broken, the hook is out of service until repaired.

3. Brake and Internal Mechanism Rejection

• Load Drift / Slippage: During the pre-use operational check, if the hoist fails to hold a load stationary, or if the load slips downward when the hand chain or lever is released, the brake friction discs are worn, glazed, or contaminated with oil. The hoist must be tagged out immediately.
• Ratchet Teeth and Pawls: Chipped, cracked, or rounded ratchet teeth; broken, stuck, or missing pawl return springs; or loose pawl pivot pins.

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3. The Lift Plan: Routine vs. Critical Lifts

In professional construction, lifts are categorized into two operational classes: routine (simple) lifts and critical lifts.

Routine (Simple) Lifts

A routine lift involves standard materials, cataloged equipment, and repetitive rigging operations where:

• The load weight is well known and verified.
• The crane or hoist operates well within its normal rated load chart capacity (typically below 75%).
• Standard, pre-inspected rigging slings and hardware are deployed in basic hitches.
• The hoisting path is clear of energized utilities, buildings, and ground personnel.

Critical Lifts: Definition and Triggers

A Critical Lift is any hoisting operation that presents an elevated risk of structural collapse, personnel injury, crane overturn, or massive financial loss. Under OSHA regulations, ASME standards, and corporate site safety policies, a lift is formally classified as a Critical Lift if it meets ANY of the following criteria:

1. High Capacity Utilization: The weight of the load, rigging, and hook block exceeds 75% (or 80% per some site standards) of the crane's rated load chart capacity for the required radius and boom angle.
2. Tandem / Multi-Crane Lifts: Two or more cranes are required to hoist, rotate, or position a single shared load. Tandem lifts are hazardous because dynamic crane movement can shift load weight unexpectedly from one crane to the other.
3. Hoisting Personnel: Lifting employees in a crane-suspended personnel platform (man basket) under OSHA 29 CFR 1926.1431.
4. Lifts Over High-Hazard Zones: Hoisting over active, occupied buildings; energized high-voltage power lines; active rail lines; or operating chemical, gas, or process pipelines.
5. Specialized or Complex Loads: Non-symmetrical loads with an unverified center of gravity; submerged loads subject to water drag and bottom suction forces; or tilt-up precast concrete panels.

Elements of an Engineered Critical Lift Plan

Before executing a critical lift, a formal, documented, engineered Critical Lift Plan must be developed, reviewed, and signed off by a Qualified Engineer, Lift Director, Crane Operator, and Qualified Rigger. The plan must contain:

• Precise load weight documentation, including structural components, internal liquids, and rigging gear.
• Accurate Center of Gravity (CG) location and pick point calculations.
• Crane configuration: exact model, counterweight, boom length, jib angle, operating radius, and percentage of load chart capacity utilized.
• Ground bearing capacity analysis, soil compaction reports, outrigger pad sizing, and timber matting engineering.
• Rigging hardware schedule: sling types, lengths, horizontal angles, shackle sizes, spreader beam engineering, and softeners.
• 3D hoisting path mapping showing clearances to power lines, scaffolding, and adjacent structures.
• Designated, qualified personnel: Lift Director, Crane Operator, Qualified Rigger, and Qualified Signalperson.
• Emergency contingency and weather abort thresholds (maximum allowable wind speeds, gust limits, lightning shutdown protocols).

Pre-Lift Checklist and Exclusion Zones

Prior to hoisting, the site supervisor and rigging crew must enforce site controls:

• Exclusion Zone Barricades: The entire fall zone beneath the load path and the swing radius of the crane superstructure must be physically barricaded with hazard tape, stanchions, or fencing to prevent unauthorized entry.
• Pre-Lift Meeting (Toolbox Talk): A mandatory briefing with all involved craftworkers to review lift sequence, radio channels, hand signals, and emergency stop authority.

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4. The Mandatory Test Lift Procedure

Regardless of whether a lift is routine or critical, executing a Test Lift is a non-negotiable safety requirement before any load is hoisted into its travel path:

                     MANDATORY 4-STEP TEST LIFT PROCEDURE
                     
     Step 1: HOIST 2 TO 4 INCHES
             Gently raise load 2-4" (50-100 mm) off dunnage.
             
     Step 2: FULL STOP & HOLD
             Hold load suspended stationary in mid-air.
             
     Step 3: 4-POINT SAFETY VERIFICATION
             ┌────────────────────────────────────────────────────────┐
             │ [1] BRAKE HOLD: Verify zero hoist brake slip or drift.  │
             │ [2] RIGGING SEAT: Slings seated in hooks/shackles.     │
             │ [3] LEVEL & BALANCE: Verify hook is plumb over CG.      │
             │ [4] TAGLINE READY: Riggers outside fall zone.          │
             └────────────────────────────────────────────────────────┘
             
     Step 4: PROCEED OR ABORT
             If ANY tilt, slippage, or imbalance occurs ──►
             IMMEDIATELY LOWER BACK TO DUNNAGE & RE-RIG!