Inspection & testing
Sling inspection: what to check, when, and when to remove from service
Updated August 1, 2026 · 3 minute read · All guides
In short
Slings are inspected at three levels: visually before every use by the person rigging, periodically by a competent person on a documented schedule, and immediately whenever damage is suspected. An alloy chain sling is removed from service for cracks, stretch, excessive wear at link bearing points, gouges, bent or twisted links, heat damage, an opened hook throat, a latch that will not close, or a missing or illegible tag.
Key facts
- Three tiers: pre-use visual, periodic documented inspection, and immediate inspection on damage or doubt.
- Twelve months is a common periodic baseline for normal service. Severe service shortens it considerably.
- A missing or illegible tag is itself a removal criterion: an unidentifiable sling cannot be rated.
- Measure wear and stretch against the original dimensions, which is why recording them at first use is worth the five minutes.
- Damaged slings should be destroyed or physically prevented from returning to service, not set aside.
The three tiers
Before every use. Carried out by whoever is rigging the load. It is a look and a feel, not a measurement exercise: obvious damage, deformation, a tag that can still be read, a latch that closes.
Periodic. Carried out by a competent person on a documented schedule, with a written record. The interval is set against how severely the sling is used. Twelve months is the common baseline for normal service; a sling in daily precast or trench service earns a much shorter interval.
On damage or doubt. Any sling involved in an incident, a shock load, a suspected overload, or exposure to heat or chemicals comes out of service until a competent person clears it.
Removal criteria for alloy chain slings
Remove from service if any of the following is present:
- Missing, illegible or unattached tag. An assembly that cannot be identified cannot be rated.
- Cracks or breaks anywhere in chain, fittings or master link.
- Excessive wear at link bearing points. Wear reduces the load bearing cross section, and it concentrates exactly where links contact each other.
- Stretch. Links that have elongated indicate the chain has been overloaded. Measure a defined number of links against the original length.
- Gouges, nicks, or sharp transverse marks, particularly across a link.
- Bent, twisted or deformed links.
- Heat damage or weld spatter. Alloy chain is heat treated; uncontrolled heat undoes that.
- Hook throat opening beyond the manufacturer's limit, or a hook that is twisted out of plane.
- A latch that does not close or does not lock.
- Corrosion pitting that has reduced the section.
Why original dimensions matter
Most removal criteria are comparative: this link is longer than it was, this section is thinner than it was. If nobody recorded what it was, the inspection becomes a judgement call rather than a measurement.
Recording two numbers when a sling first enters service solves this permanently:
- Reach, measured consistently from a defined point.
- Length over a set number of links, marked so the same links are measured next time.
Five minutes on day one, and every subsequent inspection becomes objective.
Synthetic and wire rope slings differ
The tiers are the same; the criteria are not.
Web and round slings come out of service for: missing or illegible tag, acid or caustic burns, melting or charring, holes, tears, cuts or snags, broken or worn stitching in load bearing splices, excessive abrasion, knots, discolouration or brittleness suggesting UV degradation, and damaged or corroded fittings. On round slings, any damage that exposes the load bearing core is immediate removal.
Wire rope slings come out for: broken wires above the allowable count in a given length, localised broken wire clusters, kinking, crushing, birdcaging, corrosion, heat damage, and damaged end fittings or thimbles.
Records that hold up
An inspection record is only useful if it identifies the specific sling. Record:
- The serial number from the tag
- Inspection date and inspector
- Findings, including measurements against original dimensions
- Outcome: returned to service, or removed
- The next scheduled inspection date
Tying records to serial numbers rather than to descriptions is what makes an inspection programme survive branch transfers and staff changes.
What to do with a failed sling
Destroy it or make it physically unusable, and remove it from the yard. A damaged sling set aside "to deal with later" returns to service. Cutting the assembly is the standard practice, and it takes less time than the conversation that follows if it does not happen.
How to run a periodic sling inspection
A documented periodic inspection of an alloy chain sling by a competent person.
- 1Identify the assemblyRecord the serial number from the tag. If the tag is missing or illegible, the sling is removed from service at this point and the inspection stops.
- 2Clean the assemblyRemove dirt, grease and build-up so that link surfaces, welds and fitting bodies can actually be seen.
- 3Measure against original dimensionsCheck reach and length over a marked set of links against the recorded original. Elongation indicates overload.
- 4Examine every link and fittingLook for cracks, wear at bearing points, gouges, bends, twists, heat damage and corrosion. Check hook throat opening against the manufacturer's limit and confirm latches close and lock.
- 5Record the outcomeLog findings, measurements, the outcome and the next inspection date against the serial number. Return to service or remove and destroy.