Alloy-Chain and Metal-Mesh Sling Inspection

Alloy-Chain and Metal-Mesh Sling Inspection

Alloy steel chain identity

A lifting chain sling is a rated assembly, not a length of chain chosen by appearance. OSHA 1910.184 requires permanent, durable identification stating chain size, grade, rated capacity, and reach. Confirm the number of legs, attachments, and hitch information required by the applicable tag and manufacturer.

Only chain identified and rated for lifting may be used. Grade 70 transport chain, proof coil, hardware-store chain, and an unmarked chain are not substitutes for a tagged alloy lifting sling. Attachments must have a rating at least equal to the chain, or the assembly is limited to its weakest rated component. Bolts, rods, and makeshift links are prohibited.

Chain inspection sequence

Inspect the master link, every chain link, coupling devices, shortening devices, hooks, and other attachments. Clean enough to see the metal without using a method that hides or causes damage. Look for:

• missing or illegible identification;
• cracks, nicks, gouges, or weld damage;
• bent, twisted, stretched, or distorted links;
• wear at bearing surfaces;
• heat discoloration, weld spatter, or arc strikes;
• severe corrosion or pitting;
• links that bind and do not hinge freely;
• damaged latches, pins, coupling links, or master links; and
• an increase in reach or other evidence of elongation.

Measure suspect links at the worn cross-section and compare with the exact applicable table or manufacturer limit. Do not measure only a neighboring unworn surface.

OSHA 1910.184 Table N-184-1 gives minimum allowable size at any point of the link. For nominal 1/2-inch chain, the minimum is 25/64 inch. That corresponds to maximum wear of 7/64 inch, not a generic “10% of every chain size.” Other nominal sizes have different table values, and a current B30.9 or manufacturer limit may be more restrictive.

Chain inspection frequency and records

In general industry, a designated competent person inspects the sling and attachments each day before use and additionally when service conditions warrant. Alloy-chain slings also receive a thorough periodic inspection based on use frequency, service severity, experience with sling life, and the nature of lifts. The interval may not exceed 12 months. The employer records the month of the most recent periodic inspection and makes the record available.

In construction, 1926.251 requires inspection before use on each shift and as necessary during use. Keep the governing workplace rule clear; do not claim that OSHA requires identical annual records for every sling material.

Chain temperature and repair

If an alloy-chain sling is heated above 1,000°F, OSHA requires permanent removal. For service temperatures above 600°F, reduce maximum working load according to the chain or sling manufacturer's recommendations. Do not apply a memorized percentage to every grade.

Worn or damaged chain and attachments cannot be used until properly repaired. Welding or heat repair must be performed by the sling manufacturer or an equivalent entity, followed by required proof testing. Low-carbon repair links and field-made mechanical substitutes are not allowed to repair broken chain.

Never field-straighten, heat, weld, or grind a load-bearing link. Segregate removed gear so it cannot re-enter service.

Metal-mesh sling identity and use

A metal-mesh sling has flexible wire-mesh fabric joined to metal handles. Its durable marking states rated capacity for vertical, basket, and choker loading. Confirm the handle and fabric are compatible and the load is distributed across the fabric width.

Uncoated metal-mesh slings may be used under OSHA from minus 20°F to 550°F without reducing WLL. Mesh impregnated with PVC or neoprene is limited from 0°F to 200°F. Outside those ranges, or for other coatings, follow the manufacturer.

New and repaired metal-mesh slings require proof testing by the manufacturer or equivalent entity at a minimum of 1.5 times rated capacity. That test does not increase the operating rating.

Exact OSHA metal-mesh removal criteria

Remove a metal-mesh sling immediately for any of these conditions:

• a broken weld or brazed joint along the sling edge;
• wire-diameter reduction of 25% from abrasion;
• wire-diameter reduction of 15% from corrosion;
• loss of flexibility from fabric distortion;
• female-handle slot depth increased by more than 10%;
• either handle's eye width decreased by more than 10%;
• a 15% reduction in original metal cross-sectional area anywhere around a handle eye; or
• either handle distorted out of its plane.

These criteria are not “one broken edge wire or two body wires,” and abrasion and corrosion have different percentages. Inspect the entire fabric for crushed, bent, or distorted spirals and cross rods, but connect an exact rejection answer to the exact stated source.

Repairs must be performed by a metal-mesh sling manufacturer or equivalent entity. After repair, mark or record the repair date, nature, and responsible organization as OSHA requires.

Exam method

First identify whether the specimen is alloy chain or metal mesh. Check its tag. For chain, walk every link and attachment, measure wear against the right table, and consider heat. For mesh, inspect edge joints, wire loss, flexibility, and handle geometry. State the defect and disposition. Never substitute an across-the-board 10% rule for the material-specific criterion.