Wire rope sling care and maintenance
By Alex Dahm08 January 2009
Terry Young, president of Construction Safety Experts, in the US, discusses identification, inspection and removal criteria for wire rope slings. The ASMEB30.9-2006 Standard requires each wire rope sling to show the name or trademark of the manufacturer, diameter or size, number of legs, if more than one, and the rated loads for the types of hitches used and the angle upon which it is based.
The initial identification is done by the manufacturer and should be maintained by the user so as to be legible during the life of the sling. Replacement of the sling identification should be considered as a repair and is required to be performed by the manufacturer or a qualified person. It must be marked to identify the repairing agency.
Additional proof testing is not required when replacing sling identification.
An initial inspection should be performed prior to using new, altered, modified or repaired wire rope slings. It should be conducted by a designated person to verify compliance with applicable ASME 30.9-2006 standards.
A frequent visual inspection for damage must be performed by the user or designated person each day or shift the sling is used. The best safety practice is to inspect the wire rope before each use, task or lift.
Any condition meeting the ASME 30.9 - 2006 removal criteria or other condition that may result in a hazard must result in the sling being removed from service. The sling should then not be returned to service until approved by a qualified person. Written records are not required for frequent inspections.
A periodic inspection is to be conducted at intervals, not exceeding one year. This requires a complete inspection for damage to the sling by a designated person. The inspection should be conducted on the entire length, including splices, end attachments and fittings.
The frequency of periodic inspections should be based on frequency of use, severity of service conditions, nature of lifts being made and experience gained from the service life of slings used in similar circumstances or conditions.
Guidelines for the time intervals are
Normal service - yearly
Severe service - monthly to quarterly
Special service - as recommended by a qualified person or manufacturer
A written record shall be made and maintained of the most recent periodic inspection
A wire rope sling shall be removed from service if conditions such as the following are present.
- Missing or illegible sling identification
- Broken wires
- For strand- laid and single-part slings, 10 randomly broken wires in one rope lay, or five broken wires in one strand in one lay.
- For cable-laid slings, 20 broken wires per lay.
- For six- part braided slings 20 broken wires per braid.
- For eight-part braided slings 40 broken wires per braid.
- Severe localized abrasion or scraping
- Kinking, crushing, birdcaging or any other damage resulting in damage to the rope structure
- Evidence of heat damage
- End attachments that are cracked, deformed or worn to the extent that the strength of the sling is substantially affected
- Severe corrosion of the rope, end attachments or fittings.
- Other conditions including visible damage that may cause doubt to the continued use of the sling
Hook removal criteria is listed in the ASME B30.10 Standard. Rigging hardware removal criteria is listed in the ASME B30.26 Standard.