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newSchoolWorks.com › VoTechWorks › Building & Construction › Electrical Lineworker › Rigging for Electrical Linework › Lesson 2
BLD-LINE69-04 · Lesson 2 · 7 clock hours · lab

Inspection Procedures and Discard Criteria

Objective. Students will inspect a set of wire rope, chain, synthetic sling, and hardware specimens against published discard criteria and produce a written inspection log that correctly accepts, flags for monitoring, or removes from service each item.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed professional engineer or master tradesperson or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

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Why Inspection Matters

Every piece of rigging equipment that leaves the ground carries not only the load but every life working beneath it. A wire rope that fails mid-lift, a sling with a hidden cut, or a hook twisted past its rated geometry can drop tons of material in a fraction of a second. Lineworkers routinely rig conductors, transformers, cross-arms, and pole sections weighing hundreds or thousands of pounds. Knowing exactly when to pull a piece of rigging from service—and being able to defend that decision in writing—is a core professional skill and a legal obligation.

ASME B30.9 covers slings (wire rope, chain, synthetic, and metal mesh). ASME B30.10 covers hooks. These standards are the industry-accepted discard criteria references you will use in today's lab and throughout your career.

Personal Protective Equipment for Inspection

Before touching any rigging, put on nitrile gloves and safety glasses. Wire rope is covered in fine broken-wire ends that will puncture bare skin. Gloves let you run the rope slowly through your hand without embedding wires in your palm. Safety glasses protect against debris knocked loose during handling. Never rush this step—an injured inspector cannot complete the log.

Wire Rope Inspection

Wire rope is made of individual wires twisted into strands, which are then laid around a core. Inspection is a systematic, slow process.

How to run the rope: Hold a folded rag or gloved hand loosely around the rope and move it along the rope's length, rotating the rope as you go so you see every strand. Work in good light; use a magnifying glass for suspected damage.

Broken wires: Count the number of broken wires within one lay length (the distance for one strand to make one complete spiral around the rope). ASME B30.9 general discard criteria: remove from service if you find six or more randomly distributed broken wires in one lay length, or three or more broken wires in one strand in one lay length. Always cite the specific table in B30.9 when recording your finding.

Diameter loss: Measure with calipers at the rope's largest cross-section point. A reduction in diameter of more than one-third of the nominal diameter indicates core or internal wire failure—remove from service.

Kinking: A kink is a permanent sharp bend that has distorted the wire geometry. Any kink is an automatic remove-from-service condition; the wire geometry cannot be restored.

Bird-caging: Bird-caging appears as strands spreading outward like a cage. It results from sudden shock loading. Remove from service immediately.

Heat damage and core exposure: Discoloration, melted lubricant, or a visible fiber core protruding from the rope all indicate serious internal damage. Remove from service.

Chain Sling Inspection

Chain slings must be inspected link by link. Key criteria under ASME B30.9:

Synthetic Sling Inspection

Synthetic (web or round) slings are inspected visually and by touch. Remove from service for:

Hook Inspection

Hooks are governed by ASME B30.10. Criteria for removal:

Shackle Inspection

For screw-pin shackles: the pin must be straight, fully seated, and the safety wire (mouse wire) must be intact if required. A bent pin cannot carry rated load and must be removed from service. Thread damage that prevents full engagement is also cause for removal.

Completing the Inspection Log

Every entry in the Rigging Inspection Log must include: item description, unique identifier or tag number, the specific defect observed (or "no defect noted"), the disposition (in service / monitor / remove from service), and the exact ASME standard and criterion cited. Vague entries like "looks bad" are unacceptable. If you flag an item as "monitor," document exactly what you will monitor and at what interval. Condemned items must be immediately removed from the work area and rendered unusable or tagged so they cannot be returned to service accidentally.

Safety Summary

Never place a condemned item back with serviceable rigging. Never override a remove-from-service decision based on schedule pressure—no lift is worth a fatality. Document everything; the written log is both a safety record and legal protection for you and your employer.

Key terms8

Lay lengthThe axial distance along a wire rope in which one strand makes one complete helical wrap around the rope core; used as the reference length for counting broken wires.
Bird-cagingA wire rope defect in which the strands splay outward from the core, resembling a birdcage, caused by sudden compressive or shock loading; an immediate remove-from-service condition.
KinkA permanent sharp bend in wire rope that permanently distorts the wire and strand geometry, making the rope unfit for further service regardless of visible wire breaks.
ASME B30.9The American Society of Mechanical Engineers standard that establishes design, inspection, testing, and discard criteria for slings, including wire rope, chain, synthetic, and metal mesh types.
ASME B30.10The ASME standard governing the design, installation, inspection, and removal-from-service criteria for hooks used in rigging and lifting operations.
Throat openingThe distance across the inside opening of a hook; a throat opening exceeding 15 percent beyond the normal unstretched dimension is a discard criterion under ASME B30.10.
Nick (chain)A gouge or notch cut into the surface of a chain link; when a nick reduces the cross-sectional diameter of the link by more than 10 percent, the sling must be removed from service per ASME B30.9.
Remove from serviceA formal disposition indicating that a piece of rigging equipment must be immediately withdrawn from use, tagged or rendered unusable, and not returned to service without authorized inspection or replacement.

Worked examples3

1. You measure a wire rope that has a nominal (rated) diameter of 0.75 inch. At the point of suspected damage, your calipers read 0.49 inch. Does the diameter loss meet the discard criterion?
  1. Identify the allowable diameter reduction limit: ASME B30.9 requires removal from service when diameter loss exceeds one-third of the nominal diameter.
  2. Calculate one-third of the nominal diameter: 0.75 in ÷ 3 = 0.25 in maximum allowable loss.
  3. Calculate the actual diameter loss: 0.75 in − 0.49 in = 0.26 in actual loss.
  4. Compare: 0.26 in actual loss > 0.25 in allowable loss.
Answer: Yes. The diameter loss of 0.26 inch exceeds the one-third-of-nominal-diameter limit of 0.25 inch. Log disposition: Remove from service. Cite ASME B30.9 diameter reduction criterion.
2. Inspecting a chain sling, you measure a link's cross-sectional diameter at the nick location as 0.41 inch. The link's undamaged diameter measured on the opposite side is 0.46 inch. Does the nick meet the 10-percent discard criterion?
  1. Identify the undamaged (nominal) link diameter: 0.46 in.
  2. Calculate 10 percent of the nominal diameter: 0.46 in × 0.10 = 0.046 in.
  3. Calculate the actual material lost to the nick: 0.46 in − 0.41 in = 0.05 in.
  4. Compare: 0.05 in actual loss > 0.046 in (10 percent threshold).
Answer: Yes. The nick removes 0.05 inch of material, which is more than 10 percent of the nominal link diameter (0.046 inch). Log disposition: Remove from service. Cite ASME B30.9 chain nick criterion.
3. A hook's throat opening normally measures 2.00 inches. After suspected overload, you measure 2.28 inches. Has the 15-percent threshold been exceeded?
  1. Calculate 15 percent of the normal throat opening: 2.00 in × 0.15 = 0.30 in maximum allowable increase.
  2. Calculate the actual increase: 2.28 in − 2.00 in = 0.28 in.
  3. Compare: 0.28 in actual increase < 0.30 in allowable increase.
Answer: No. The throat has opened 0.28 inch, which is less than the 0.30-inch (15 percent) threshold. However, document the measurement in the log and flag as 'monitor,' noting the exact measurement and re-inspection interval, because the hook is approaching the discard limit.
In class: Instructor demonstration of wire rope inspection technique—running the rope slowly through a gloved hand, counting broken wires per lay, measuring diameter loss, checking for kinking, bird-caging, heat damage, and core exposure—using a section of worn rope projected on a document camera. · Students individually inspect a prepared set of ten specimens (some acceptable, some intentionally condemned: kinked wire rope, sling with a cut, chain link with a nick over 10% of cross-section, hook with a twist, shackle with a bent pin) and complete a standardized Rigging Inspection Log form, marking each as 'in service,' 'monitor,' or 'remove from service' with the specific criterion cited. · Debrief and calibration exercise: instructor reveals the pre-determined disposition of each specimen; students self-score, and the class discusses any disagreements, referencing ASME B30.9 and B30.10 tables directly.
Materials: Prepared specimen set (condemned and serviceable items), wire rope inspection gauge, calipers, magnifying glass, Rigging Inspection Log forms, ASME B30.9 and B30.10, nitrile gloves, safety glasses.
Check: Rigging Inspection Log graded by instructor; students must correctly dispose of 9 of 10 specimens and cite the correct standard criterion for each condemned item—pass requires 90% accuracy on dispositions.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Rigging and Lifting Safety
1. According to ASME B30.9, the general criterion for removing a wire rope sling from service based on broken wires is finding how many randomly distributed broken wires within one lay length?
Rigging and Lifting Safety
2. A wire rope has a nominal diameter of 0.50 inch. The measured diameter at the damage site is 0.32 inch. What is the correct disposition?
Rigging and Lifting Safety
3. Which of the following wire rope defects is an automatic remove-from-service condition regardless of the number of broken wires present?
Rigging and Lifting Safety
4. Under ASME B30.9, a synthetic web sling must be removed from service if its load-rating tag is:
Rigging and Lifting Safety
5. ASME B30.10 requires a hook to be removed from service when the throat opening has increased by more than what percentage of the normal (unstretched) dimension?
Rigging and Lifting Safety
6. During a chain sling inspection, you observe a crack at the weld point of one link. What is the correct action?
Workplace Safety / OSHA
7. What minimum personal protective equipment must be worn when physically handling wire rope during an inspection?
Rigging and Lifting Safety
8. A student's Rigging Inspection Log entry reads: 'Shackle—looks bent—remove from service.' Why would an instructor mark this entry as incomplete?
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