8.1 Hook Inspection (ASME B30.10)
Key Takeaways
- ASME B30.10 governs hook inspection and removal concepts: throat opening increase, out-of-plane twist, saddle wear, cracks, tip damage, heat damage, and latch function when a latch is required.
- Industry training commonly teaches throat-opening increase limits around 5% or 15% of original—state the concept carefully, measure against original geometry, and follow the manufacturer and current B30.10/employer chart for the exact number.
- Never side-load a standard hook; inspect for side-load evidence such as tip/latch damage, bent shanks, and loads that rode the tip instead of the saddle.
- Hooks must carry legible capacity/marking information; unreadable identification or any condition that creates doubt means remove from service—do not re-rate a damaged hook in the field.
8.1 Hook Inspection (ASME B30.10)
Quick Answer: Inspect hooks under ASME B30.10 for throat opening increase, twist, saddle wear, cracks, tip damage, heat damage, and latch function (when a latch is required). Never side-load a standard hook. Confirm markings and capacity. Any reject condition or doubt → remove from service.
Hooks are single-point load path components. When a hook opens, cracks, or is side-loaded off the saddle, the failure can drop the entire load with no intermediate warning. Inspection is roughly 30% of the Level I written blueprint, and the practical exam’s Pre-Use Inspection mindset includes recognizing defective hooks on assemblies. This section focuses on what a Level I rigger must see and do every use—not on designing hooks or rewriting manufacturer charts.
Where B30.10 Fits
ASME B30.10 addresses hooks used in lifting service (crane hooks, hoist hooks, and related designs within the standard’s scope). Level I does not require memorizing every B30.10 clause number, but you must connect the standard name to inspection and removal concepts and to safe loading in the saddle.
Hooks may be:
| Hook context | Inspection ownership |
|---|---|
| Crane / hoist hook | Often operator or designated person for the equipment; rigger still refuses a hook that is visibly defective before attaching rigging |
| Hook on a sling assembly | Rigger’s frequent inspection of the sling assembly includes the hook |
| Detachable rigging hook | Inspect as hardware before each use |
Regardless of who “owns” the equipment record, you do not attach to a hook that fails visual criteria.
Frequent Inspection Sequence for Hooks
Work the same order every time so defects are not skipped under schedule pressure:
- Identification / capacity marking — Read WLL or capacity markings, manufacturer ID, and any required grade or product marks. Missing or illegible capacity information → out of service for that hook until properly identified or replaced.
- Overall geometry — Look down the plane of the hook. Is the tip still aligned? Is the throat visibly sprung open compared with a sister hook or known original shape?
- Saddle (bowl) — The load-bearing seat. Check wear, grooves, and polish patterns that show where the load rode.
- Tip and latch area — Tip deformation, latch missing, bent, or not closing fully across the throat.
- Shank, swivel, and connection — Cracks, bent shank, worn threads or pin holes, seized swivel, missing cotter/retention where applicable.
- Surface defects — Cracks, deep nicks, gouges, arc strikes, heat color, severe corrosion.
- Disposition — Accept for use, or tag, segregate, and report.
Clean mud and paint enough to see the metal you are judging. Do not “tap test” a cracked hook back into service.
Throat Opening Increase (State the 5% / 15% Concepts Carefully)
Throat opening is the clear distance across the hook mouth (commonly described from the saddle/inside geometry toward the tip—training diagrams vary slightly, but the idea is the opening that grows when a hook is permanently sprung).
When a hook is overloaded, shock-loaded, or tip-loaded, the throat can open permanently. That permanent set reduces the hook’s ability to retain the load and is a classic remove-from-service driver.
How Industry Teaches the Numbers
Training materials and manufacturer guidance commonly present throat-opening increase limits on the order of about 5% of original or about 15% of original, depending on the standard edition, product instructions, and course source. Both figures appear in rigger education; they are not interchangeable free-choice numbers you invent on site.
| Teaching concept | Level I takeaway |
|---|---|
| ~5% of original throat opening | Some industry/exam-oriented materials teach a relatively tight increase limit; any permanent opening beyond the governing chart is reject |
| ~15% of original throat opening | Other widely used training and manufacturer-style criteria cite a 15%-of-original increase as a removal threshold |
| Manufacturer / current B30.10 / employer chart | Controlling source for the exact numeric limit on your hook |
| Visible permanent set | Even without calipers, a hook that is obviously sprung open relative to original geometry is a stop—measure when possible; never normalize a “slightly opened” hook for “light loads” |
Exam and field discipline:
- Know that throat opening increase beyond the acceptance criterion = remove from service.
- Prefer answers that remove a permanently opened hook rather than “use at half capacity.”
- When a scenario quotes a specific percentage from a manufacturer or standard, apply that criterion.
- When no number is given but the hook is described as opened, sprung, or stretched at the throat, treat it as defective.
Measure increase against original throat dimension (new-hook data, manufacturer drawing, or a matching undamaged hook of the same model when allowed by procedure)—not against “how it looked last month after it already opened a little.”
Twist (Out-of-Plane Distortion)
A serviceable hook’s tip and saddle generally lie in a designed plane. Twist means the tip has rotated out of that plane—often from side loading, improper two-point attachment, or impact.
Industry teaching often flags twist on the order of about 10 degrees from the original plane as a removal concept, with manufacturer/B30 criteria controlling the exact limit. For Level I:
| Observation | Action |
|---|---|
| Tip visibly twisted out of plane | Remove from service |
| Hook “walks” loads toward the tip under tension because geometry is distorted | Remove from service |
| Doubt about remaining alignment | Remove / competent-person evaluation—do not guess |
Twist and throat opening often appear together after misuse. Either one can condemn the hook.
Wear in the Saddle
The saddle (bowl) is where the sling eye, shackle, or master link should seat. Wear reduces cross-section and can create a sharp groove that cuts slings or concentrates stress.
Common teaching: wear exceeding about 10% of the original sectional dimension in critical areas is a removal concept—again subject to manufacturer tables. Field signs:
- Deep polished groove in the saddle
- Knife-edge feel at the wear track
- Asymmetric wear showing chronic side or tip loading
Severe saddle wear → remove from service. Do not “smooth it with a grinder” in the field unless working under an authorized repair process (generally not Level I scope).
Cracks, Nicks, Gouges, and Surface Damage
| Defect | Why it matters | Typical disposition |
|---|---|---|
| Cracks | Propagate under cyclic tensile load; catastrophic open-up risk | Immediate removal |
| Deep nicks / gouges | Stress risers; reduced section | Remove if they impair strength or meet manufacturer reject depth |
| Arc strikes / weld splash | Localized hard/brittle zones, hidden cracks | Remove / evaluate—exam favors removal when heat/weld damage is evident |
| Severe corrosion / pitting | Section loss; hides cracks | Remove when strength is doubtful |
Any crack in a hook is a hard stop. Dye-penetrant and magnetic-particle methods may appear in periodic programs; frequent inspection is visual and tactile—if you see a crack line, the hook is done.
Latch Function (When a Latch Is Required)
Many hooks have a latch (self-closing spring latch, gravity latch, or similar) intended to help retain slings and hardware during slack conditions. Critical exam facts:
- A latch is a retention aid, not a license to tip-load or side-load.
- If site rules, equipment design, or the lift plan require a latch, the latch must be present and functional—closes across the throat, not bent open, spring not broken, latch not missing.
- A damaged or missing latch on a latched-hook application is a service issue: repair/replace per manufacturer or remove the hook from service—do not “make do.”
- Never put load on the latch as if it were a load-bearing member.
| Latch condition | Action |
|---|---|
| Latch closes fully and freely when required | Accept (if hook otherwise sound) |
| Latch missing, bent, seized, or will not close | Remove/repair before use when latch is required |
| Crew proposes loading against the latch | Stop—incorrect loading |
Tip Damage and Heat Damage
Tip damage includes mushrooming, bending, cracks at the tip, or evidence the load climbed the tip. Tip loading and side loading are primary causes. A deformed tip changes throat geometry and retention—remove from service when the tip is damaged beyond manufacturer acceptance.
Heat damage may show as blueing, black scale, arc marks, or nearby evidence of cutting/welding. Heat can reduce strength without a dramatic open throat. Evidence of excessive heat → remove from service (or follow manufacturer disposition—exam answers favor removal).
Never Side-Load — And Inspect for Side-Load Evidence
Standard hooks are designed for loading in the saddle, in the plane of the hook. Side loading (out-of-plane) and tip loading are misuse modes that open, twist, or crack hooks.
| Loading | Acceptable on ordinary hook? |
|---|---|
| Load centered in the saddle, in plane | Yes (within rated capacity and fit) |
| Load on the tip | No |
| Load on the latch | No |
| Out-of-plane / side load | No (unless specifically designed/rated for that load path) |
| Multiple eyes crowding toward the tip | Correct with shackle/master link; do not force tip loading |
Side-load evidence during inspection
Look for clues that the last user side-loaded or tip-loaded the hook:
- Wear polish high on the tip rather than in the saddle
- Bent or sprung tip; twisted plane
- Damaged or sprung latch from eyes climbing the tip
- Bent shank or elongated pin hole from off-axis pull
- Shackle or sling still oriented as if it had been forced against the tip
If evidence shows chronic side loading, do not return the hook to service “because it hasn’t broken yet.” Remove it and fix the rigging practice (use a shackle, master link, or properly rated hardware so eyes seat in the bowl).
Marking and Capacity
A hook in lifting service must be identifiable for capacity. Markings may include WLL/capacity, manufacturer identification, and size. Rules of engagement:
| Check | Pass concept | Fail concept |
|---|---|---|
| Capacity legible | You can read the rating that applies | Paint, wear, or damage erased the rating |
| Matches the lift | Hook capacity ≥ applied load share with required factors | Undersized hook used because “it fit the eye” |
| Traceability | Matches equipment ID / inspection program when required | Unknown unmarked farm hook used as a crane hook |
Never assume capacity from throat size alone. Never re-stamp a higher rating. If markings are gone, the hook is out of service until properly identified under a competent process—or scrapped.
Removal Criteria Quick Reference (Hooks)
| Condition | Action |
|---|---|
| Throat opening permanently increased beyond manufacturer/B30 criterion (commonly taught ~5% or ~15% of original—use the governing source) | Remove from service |
| Twist / out-of-plane distortion beyond criterion (often taught ~10°) | Remove from service |
| Saddle or section wear beyond criterion (often taught ~10% original dimension) | Remove from service |
| Cracks, deep nicks/gouges that impair strength | Remove from service |
| Tip damage, bent tip, or evidence of tip loading damage | Remove from service |
| Heat damage / arc strikes / weld damage | Remove from service |
| Required latch missing or inoperative | Remove/repair before use |
| Missing or illegible capacity marking | Remove from service until identified or retired |
| Any condition creating doubt as to continued safe use | Remove pending competent evaluation |
Integrating Hook Inspection with the Lift
- Confirm hook capacity and condition before hanging slings.
- Seat hardware in the saddle; use a shackle when multiple eyes will not center properly.
- After any shock load, two-blocking near-miss, side pull, or known overload, re-inspect the hook before the next pick.
- Tag and segregate rejects so nobody reuses a sprung hook from the “almost scrap” pile.
Exam Focus
Expect items that pair a defect description (opened throat, twisted tip, cracked saddle, missing latch, heat blueing, unreadable capacity mark) with the correct action: remove from service. Distractors include using the hook at reduced load, loading on the latch, or ignoring side-load evidence. Choose answers that keep load in the saddle, respect B30.10 removal concepts, and treat markings as mandatory.
Under ASME B30.10-oriented Level I practice, what is the correct action when a hook’s throat is permanently sprung open beyond the manufacturer or standard acceptance limit?
Which statement best reflects industry teaching about throat-opening increase percentages on hooks?
A rigger notices shiny wear high on the hook tip and a bent latch, with little wear in the saddle. What does this most likely indicate, and what should the rigger do?
Which statement about hook latches is correct for Level I inspection and use?