Proof Load Testing of Hoisting Hooks

Proof load testing verifies that a hoisting hook can withstand a specified multiple of its rated load (WLL) without harmful, permanent deformation. After testing, the hook’s permanent increase in throat opening must not exceed 1% of the original opening or 0.02 in (0.5 mm), whichever is greater. Record measurements, certify the result, and remove any hook from service if it fails acceptance criteria.

How Proof Load Testing Works

• Setup: Mount the hook in a calibrated test machine with fixtures that load through the saddle as in service (never on the latch).
• Apply load: Increase smoothly to the specified proof load and hold to stabilize readings.
• Measure throat opening: Measure before and after; the permanent set must meet the limit (≤ 1% or 0.02 in / 0.5 mm).
• Inspect: Check for cracks, twist, or deformation at saddle and pin/bearing points; verify latch function and markings.
• Document: Record serial/ID, WLL, applied proof load, hold time, measurements, and pass/fail with signature.

Notes: Proof load percentages may vary by hook design, manufacturer, and size range. Always follow the current ASME B30.10 standard and the hook manufacturer’s instructions. Do not proof test using the latch.

Acceptance Criteria

• Permanent throat opening growth ≤ 1% of original or ≤ 0.02 in (0.5 mm) (whichever is greater).
• No cracking, twisting beyond limits, or deformation at the saddle/bearing points.
• Markings (WLL, manufacturer, size/grade) remain legible; latch (if fitted) operates correctly.

Documentation & Traceability

• Record hook ID/serial, size/grade, rated load (WLL), applied proof load and hold time.
• Record throat opening before/after, inspector, test machine calibration ID, and date.
• Issue a signed certificate or digital record; retain per your quality system.

Supplements

• Crane hook types

Reference

• ASME B30.10 — Hooks (use the current edition for your jurisdiction).