Using wire rope slings is one of the most reliable ways to secure a load to lifting equipment. Wire rope slings are light, strong, and durable, and they can be used in a variety of ways for many different kinds of lifts.
Because crane operators rely on wire rope slings for so many lifting operations, they must be kept in good condition for safe operation, and they should be inspected routinely for any damage or excessive wear. To ensure that all wire rope slings are properly inspected, it is important to know who should perform the inspections, how frequently inspections should be performed, and what criteria should be examined to pass an inspection. OSHA and ASME provide inspection requirements and guidelines that can be used to ensure that all wire rope slings are inspected correctly and safe for material handling operations.
When Should Wire Rope Slings be Inspected?
How often wire rope slings are inspected depends largely on how frequently those slings are used. However, there are a few universal rules for when to inspect all slings. First, every wire rope sling should be inspected upon receipt from the manufacturer. Check slings for any manufacturing flaws and that the sling received is the correct sling and meets your application’s requirements.
Next, all wire rope slings should also be inspected before using. Regardless of how frequently a sling is used, it should always be inspected prior to use, as damage to the sling could have occurred during the previous use or in the time between uses. Inspecting a sling before every use ensures that a sling that has been damaged isn’t used if the damage wasn’t noticed or reported at the time.
In addition to these universal guidelines, wire rope slings should also be inspected routinely by a Qualified Person based on how frequently and how severely they are used. ASME guidelines require periodic sling inspections by a Qualified Person yearly for normal, occasional use and monthly to quarterly for severe, frequent use. ASME B30.9 also requires these periodic inspections to be documented and kept on-record.
Who Should Inspect Wire Rope Slings?
The person inspecting the wire rope sling will be different depending on the circumstances of the inspection. Wire rope slings must be inspected prior to every use, and this inspection should be done by the operator in preparation for the lift. The operator should be a competent person, as defined by OSHA, with the necessary knowledge to perform inspections. For monthly to yearly inspections, a professional service provider or Qualified Person, as defined by OSHA, should conduct the inspection.
The inspection process is not specifically defined by OSHA or ASME, so it is the responsibility of the inspector to know and understand how to inspect the sling properly and what to look for. First, the sling should be laid out so that the entire sling is visible and easily accessible. Then the sling should be cleaned with a rag or wire brush to make the wires and fittings more visible.
Next, the sling should be inspected thoroughly along its full length, with special attention given to fittings and end attachments. Identify any points with significant wear and determine if the sling is still suitable for service. If the sling is not suitable for service, it should be removed immediately. Label slings that have been inspected and keep records of inspection dates and sling conditions.
What to Look For
There are several factors that should be examined when inspecting a wire rope sling. OSHA 1910.184(f)(5) describes several conditions that require a sling to be removed from service if they are identified. These conditions include:
- Ten randomly distributed broken wires in one rope lay, or five broken wires in one strand in one rope lay.
- Wear or scraping of one-third of the original diameter of outside individual wires
- Kinking, crushing, bird caging or any other damage resulting in distortion of the wire rope structure.
- Evidence of heat damage.
- End attachments that are cracked, deformed or worn.
- Hooks that have been opened more than 15 percent of the normal throat opening measured at the narrowest point or twisted more than 10 degrees from the plane of the unbent hook.
- Corrosion of the rope or end attachments.
OSHA 1910.184(f)(2) also states that wire rope slings must have “permanently affixed and legible identification markings.” These markings provide information regarding the maximum safe working load at various angles for different types of hitches, the size of the sling, and the manufacturer. If the identification markings on a sling are missing or illegible during inspection, the sling should be removed from service.
ASME B30.9 provides several inspection standards in addition to OSHA requirements. If eye splices show evidence of slipping or if tucked strands have moved, the sling should be removed from service. Any cracked, bent, or broken end fittings also indicate that a sling is not suitable for use. Any severe corrosion of the rope or end attachments that cause the wires to bind will require a sling to be removed from service, but light surface rust will not substantially affect a sling’s strength.
Storing slings off the ground in a cool, dry area can also help prevent corrosion. Slings are lubricated during manufacturing, but if a sling is stored outside or subjected to corrosive conditions, it should receive additional lubrication as necessary.
Safe Lifting Operation
Properly inspecting wire rope slings and removing unsafe slings from service helps keep material handling operations safe. If a sling fails during operation, equipment can be damaged, leading to long downtime and costly repairs, and workers can be put at high risk of serious injury or even death. Routinely inspecting and maintaining wire rope slings is a simple, effective way to ensure that all material handling operations are completed safely.