Considerations to Keep in Mind When Using Synthetic Slings
Construction | Manufacturing | Rigging | Hoisting & Lifting Equipment | Inspection & Maintenance | Safety and Training | By Rob Bruno | Jul 15, 2020
Synthetic slings are used in a wide range of industries around the world and have become a go-to for many riggers due to their flexibility, lightweight, and ease of handling. The downside? You need to pay extra attention when inspecting and rigging loads.
The first two considerations are related to frequent inspections for synthetic slings. ASME B30.9 requires a frequent inspection to be performed each day or shift before rigging with a synthetic sling. This inspection determines whether your sling is safe for use and ensures a safe, efficient, and compliant lift.
These inspections vary depending on whether you are rigging with web slings or polyester round slings.
The frequent inspection for web slings per ASME B30.9-5.9.5 consists of checks for:
The frequent inspection for polyester round slings per ASME B30.9-6.9.5 consists of checks for:
Bearing stress is contact pressure between two separate bodies that can be high enough to damage or destroy a synthetic sling. Bearing stress is a quick and simple calculation that is often overlooked when planning a lift.
Bearing stress is increased when the sling is unevenly loaded by a curved surface. When attaching synthetics to connection hardware such as shackles, hooks, eye bolts, master links, swivel hoist rings, and any other devices with a curved radius, you will have bearing stress.
WSTDA (126.96.36.199-188.8.131.52) recommends a bearing stress value of 7,000 Lbs. /in2 during sling loading. Over 7,000 Lbs. /in2 could have damaging effects on your slings such as: tear, punctures, and rips in the sling cover which may expose core yarns, all of which warrant removal from service per ASME.
When using these products with a flat connection surface there is no need to calculate the effective width since the actual width of the flat connection surface can be used in this bearing stress calculation. There are products designed and engineered specifically for use with synthetic slings. These include the CM Weblok Connector, Flat Eye Rigging Hook, and CM Quick Connect Hooks. You’ll notice all these products feature a flat connection surface for synthetics to eliminate sling bunching, pinching and stress at the connection point.
See Table 4-5 WSTDA RS1 for recommended radii for use with round slings:
When rigging with synthetics, sling protection must always remain top of mind. Look beyond “sharp edges” or corners that could potentially damage or cut a synthetic sling. What may not look or feel sharp can become so under the weight of a load.
ASME B30.9 -6.10.4 states: slings in contact with edges, corners, protrusions, abrasive surfaces, or connecting hardware shall be protected with a material of sufficient strength, thickness, and construction to prevent damage unless the edges are adequately rounded to a suitable radius in accordance with WSTDA-RS-1 section 4.6, the sling manufacture or a qualified person.
Careful consideration must be taken when selecting sling protection to ensure the lift can be made safely and efficiently. Some of the common sling protection types available are engineered sleeves, engineered pads, metal mesh pads, and magnetic corner protectors. Always remember: what may not look or feel sharp, may still under tension, have the capability of damaging a synthetic sling. Even a round radius of smaller than the recommended diameter should be considered sharp.
Synthetic slings are used in a wide range of industries around the world and have become a go-to for many riggers due to their flexibility, lightweight, and ease of handling. This guide reviews everything you need to know before rigging with synthetic slings.
Robert Bruno is an Industry Products Trainer with Columbus McKinnon Corporation. Rob served 6 years in the U.S. Coast Guard on a 225 ft. Seagoing Buoy tender where he was a crane operator handling all shipboard rigging. After the Coast Guard, he worked for a large wire rope & sling manufacturer where he was responsible for sling fabrication & inspection, as well as offsite rigging & inspection. After moving to California, Rob worked for one of the largest synthetic sling manufacturers in the U.S. where he was responsible for Nuclear, Hydro, Aerospace, & wind energy customers. Rob joined Columbus McKinnon in November of 2017.