6.3 Chain Sling Inspection and Removal Criteria

6.3 Chain Sling Inspection and Removal Criteria

Quick Answer: Remove an alloy chain sling for stretch/elongation, nicks/gouges, bent or twisted links, excessive wear at bearing points, heat discoloration, cracks/weld defects, damaged master or coupling links, or a missing/illegible ID tag. Do not field-weld chain to “fix” it—use manufacturer-authorized processes only, or scrap it.

Alloy chain slings (often Grade 80 or 100) are favored for durability, high temperature tolerance relative to synthetics, and adjustable multi-leg configurations with shortening clutches. They are also unforgiving when stretched, gouged, or heated beyond design. Inspection is a large share of the Level I Inspection domain, and chain-specific criteria appear repeatedly on written exams and in the practical pre-use task mindset.

Alloy Chain for Overhead Lifting — Start with Identity

Before measuring wear, confirm you are looking at a lifting sling, not hardware store proof-coil chain:

Never use non-rated chain for overhead lifting. If grade marks and tags are missing or inconsistent, remove from service. Painting over grade marks or grinding marks off for “cleanliness” is a red flag.

How to Inspect a Chain Sling (Frequent Check)

1. Hang or lay out the legs so every link can be seen and articulated.
2. Read the tag — illegible/missing → out of service.
3. Flex links — each link should articulate freely; stiff or frozen links can hide wear, stretch, or corrosion products.
4. Scan every link — look for nicks, gouges, cracks, bends, twists, weld defects, and heat color.
5. Check bearing points — the inside surfaces where links rub under load wear fastest.
6. Inspect master links, coupling links, and hooks — stretch, cracks, throat opening, latch function if latches are present and required by policy.
7. Check connectors and adjusters — shortening clutches, grab hooks: cracks, wear, proper engagement surfaces.
8. Decide — serviceable or remove/tag/segregate.

Periodic inspections add measurement: calipers or go/no-go gauges for link wear, comparison of reach/length to detect elongation, and written documentation.

Defect Catalog and Removal Criteria

Stretch / Elongation

Stretch (elongation) is a signature chain failure mode after overload or progressive yield. Links may look “longer,” pitch may increase, and the sling’s reach may grow compared with original or recorded length. Stretched chain has permanently reduced cross-section effectiveness and altered geometry.

Do not “restretch” or heat-shrink chain in the field. Stretch means the steel has been loaded beyond elastic recovery for sling service.

Nicks, Gouges, and Cuts

Sharp nicks and gouges act as crack starters under cyclic tensile load. Causes include dragging over steel edges, impact from other hardware, and careless use of cutting tools nearby. Deep nicks that reduce link cross-section or create sharp notches meet removal criteria per manufacturer/B30 guidance. When in doubt about depth, remove from service and let a competent person apply the manufacturer’s acceptance chart—do not file aggressively in a way that further reduces section unless following authorized repair procedures (rare for field riggers).

Bent, Twisted, or Deformed Links

Links must remain essentially true to their manufactured shape. Bent or twisted links indicate overload, improper hitching, or side loading. Deformed master links and coupling links are equally critical—these are single-point items on multi-leg slings. Any bent/twisted/deformed link → remove from service.

Wear at Bearing Points

Interlink wear reduces the metal thickness where links bear on each other. ASME/manufacturer criteria commonly treat wear as reject when thickness is reduced beyond a stated percentage of nominal (often discussed at about 10% reduction or the manufacturer’s specific limit—always follow the manufacturer’s wear tables for the grade and size).

Periodic inspection is where wear is measured; frequent inspection still catches obvious knife-edging and should remove clearly worn chain immediately.

Heat Discoloration and Heat Damage

Heat damage may appear as blue, straw, or black discoloration, or as scale from exposure to flame, molten metal splash, or extreme process heat. Alloy chain has published temperature limits; exceeding them can change mechanical properties even if the chain still “looks strong.” Heat discoloration / evidence of excessive heat → remove from service (or follow manufacturer disposition—exam answers favor removal).

Weld Issues and Cracks

Alloy lifting chain is manufactured with controlled welds. Inspection looks for:

• Cracks at welds or in link bodies
• Incomplete or damaged welds
• Arc strikes from welding near the sling
• Unauthorized welds added in the field

Cracks = immediate removal. Any unauthorized weld is a reject condition.

Missing or Damaged Identification

Same rule as all slings: missing or illegible tags → remove from service. Tags identify grade, reach, and ratings that cannot be guessed from link size alone (different grades share sizes).

Master Links, Coupling Links, and Hooks

A perfect chain leg attached to a cracked master link is still a failed sling assembly.

Removal Criteria Quick Reference (Alloy Chain Slings)

Grade Markings — Why They Matter on the Exam

Overhead lifting alloy chain is typically Grade 80 or Grade 100 (other approved grades may exist in standards, but 80/100 dominate U.S. practice discussions). Marks on links and data on tags confirm:

• The material system and strength class
• That the product is intended for lifting (as part of a rated sling assembly)
• Compatibility when replacing components (never mix random grades/components casually)

Exam distractors may suggest using unmarked chain “if it looks heavy enough” or repairing a broken link with a carbon steel repair link from a hardware bin. Both are wrong.

Never Field-Weld Chain (Unless Manufacturer Process)

A critical safety rule:

• Do not weld on alloy chain slings in the field to close a gap, rebuild a gouge, or join links.
• Welding heat alters heat treatment and can create brittle zones and cracks.
• Repairs, when allowed at all, follow the manufacturer’s process—often meaning return to the manufacturer or an authorized facility, replacement of specific components with matched grade hardware, and re-identification/testing as required.
• Many defects are not repairable; the correct action is permanent removal and destruction so the sling cannot re-enter service.

Level I riggers should treat “we can just weld that link” as an automatic stop and refuse situation.

Comparing Alloy Chain vs Wire Rope Inspection Focus

Both product types share the same operational ethic: inspect every use, remove for criteria or doubt, never re-rate damaged gear in the field.

Multi-Leg Chain Assemblies

Inspect each leg and the head hardware. A three-leg bridle with one stretched leg is not “mostly fine.” Also verify that adjustable legs still set securely and that reach markings (if used) remain legible after shortening-clutch wear.

Uneven leg lengths from stretch can overload remaining legs and tip loads—another reason elongation is not a cosmetic issue.

Integrating Chain Inspection with Use

• Avoid shock loading; it is a prime cause of stretch and bent links.
• Keep chain off sharp corners when possible; use softeners or change hitch geometry.
• Do not tip-load hooks or hammer links to force a fit.
• After any known overload, set-down on the sling, or heat exposure, perform a careful frequent inspection before the next lift—and expect periodic inspection to measure what eyes might miss.

Exam Focus

Expect scenarios pairing a visible chain defect with the correct action: stretched links, heat blueing, missing grade/ID, deep gouges, bent master links, or a coworker proposing a field weld repair. Correct answers remove from service, segregate/tag, and reject unauthorized welding. Wrong answers reduce capacity arbitrarily, continue “if it looks okay,” or treat hardware-store chain as equivalent to Grade 80/100 alloy lifting chain.