Length: 22 Min.
Rigging Gear & Inspection Criteria
“Next to managing risk through knowledgeable competent persons and a comprehensive rigging plan, knowing the condition and capabilities of your rigging gear is the most important factor to safe lifting.”
Wire Rope Sling
The most common piece of rigging gear found in the offshore work environment is the wire rope sling.
Wire Rope Slings are basically short lengths of wire rope specially adapted for lifting attachments. They utilize Independent Wire Rope Cores (IWRC) and can be composed of:
• Improved Plow Steel (IPS)
• Extra Improved Plow Steel (XIP)
• Extra, Extra Improved Plow Steel (XXIP)
These slings are fabricated in various configurations according to the sling users required handling characteristics and lift capacities. Only certified rigging fabricators are qualified to manufacture rigging components.
A single-part sling comprised of a single wire rope in the sling body is commonly used for lifting easy to handle light to medium weight loads.
Single-leg hand-spliced rigging shall not be used in lifts where rotation may cause premature failure!
Flemish spliced eyes with swaged fittings are better suited for this use.
To provide increased capacity while allowing for greater flexibility and ease of handling, multipart slings are used. They are constructed with several wire ropes in the sling body, and can be “laid” or “braided” depending upon the customers intended use.
A braided or plaited sling, due to its construction, is often selected where loads must be rolled or maneuvered.
Advantages of Braided Slings are:
• creates friction and a gripping effect which reduces load slippage and rotation
• construction cuts spinning or twisting of free hanging loads
On multipart slings the continuous plaiting or braiding of several ropes together forms the sling body and eyes in a single fabrication operation. Ends are either hand tucked into the sling body or secured with pressed sleeves.
Sling ends can be manufactured into an assortment of eye designs and fittings, again depending upon the slings intended use.
Sling eyes, which are designed to provide what amount to be “small inverted slings” at the ends of the sling body, are formed in several ways.
* Hand spliced eyes utilize tension in the rope body to secure strands where they are tucked back into the rope.
* A mechanical splice uses a metal sleeve which is swaged around a Flemish eye splice to prevent ends from unlaying.
Sling eyes may be protected by thimbles, rubberized coatings, or wire serving. Slings with Rubberized coatings are susceptible to unseen corrosion, and are not recommended for use offshore.
Eye Hook: The eye hook with safety latch is preferred throughout the oil industry due to its features and versatility.
Sliding Choker Hook: The sliding choker hook chokes the sling snugly around a load and may be used for lifting cylindrical items or loose bundles such as casing and pipe.