North American Drillers (NAD) is one of three companies held by Shaft Drillers International (SDI) that provide geotechnical and shaft solutions to the coal mining, civil, tunnel, and undergound mining industries. NAD has expertise in shaft development approaching 20′ in diameter and 2000′ deep using a blind boring method that employs a technology known as reverse circulation.
In a unique situation, NAD found that they did not have the slings they needed to install the shaft casing that would be heavier than normal because they wouldn’t have the benefit of reverse circulation. They turned to Rouster WRR for support and were quickly provided AmSteel®-Blue slings.
THE SITUATION
The typical job involves reverse circulation, which utilizes water and compressed air to create a lighter drilling column. Once the shaft is drilled, it is lined with casing made of steel, concrete, or a composite material.
The steel or composite casing is installed in sections. Each section is lifted into place and welded to the section below it. The flooded shaft helps to displace the weight of the casing string as it grows the length of the entire shaft. Once the casing is cemented into place, the water is then pumped out of the shaft.
For this particular job, NAD was commissioned to install a new shaft into an already existing mine located in southern West Virginia. A change in the usual operations was called for: because the mine was already in place, they could not flood the shaft to displace the weight of the 497′ casing string. This meant that the slings used in the lift would ultimately need to hold the entire weight of the casing string in addition to the block and rigging, and withstand the friction of installation.
NAD typically used four 1-1/4″ diameter three-part wire rope eye-and-eye slings; however, the slings hadn’t arrived in time to complete the job. In need of an immediate solution, NAD called Rouster WRR, a Samson distributor located in Mabscott, W.Va.
THE SITUATION
NAD made the call on a Monday evening and four 2″-diameter AmSteel®-Blue grommet (or endless) slings were delivered after midnight, on Tuesday morning.
Rouster recommended AmSteel®-Blue, Samson’s most popular 12-strand single braid made with Dyneema® fiber. Proven in a multitude of marine and land-based applications since its introduction in 1996, AmSteel®-Blue yields the maximum in strength-to-weight ratio. Size for size, it is the same strength as steel.
For this particular job, Rouster WRR fabricated the 2″-diameter AmSteel®-Blue ropes into grommet slings, which provided a 5:1 factor of safety. By the time the job was completed, the casing string, block, rigging, and friction had a combined weight of 530,000 lb “on the hook”—the heaviest lift ever made by NAD.
This case demonstrates one of the greatest advantages of using AmSteel®-Blue lifting slings: its lightweight, which makes it easy and safe for crews to handle by reducing back injuries caused by the weight of wire and eliminating hand injuries caused by broken wires. However, using lightweight AmSteel®-Blue also means that the overall payload is lighter than when using heavy wire. For the NAD, this made the job easier not only for the crew, but also for the equipment making an already heavy lift.
OUTSTANDING PERFORMANCE AND SERVICE
“We were very pleased with the performance of these slings,” says John Mayfield, operations manager for SDI. “They were sure great to handle and we’ll definitely use them again.
“But the service was incredible! It would’ve normally taken a couple of days or more to get wire slings, but we had these synthetic slings in a matter of hours. That’s unheard of!”
Rouster WRR can respond quickly because they have AmSteel®-Blue in stock and the splicers on hand to fabricate slings as needed. Established in 1993, Rouster WRR has built a reputation of reliability and knowledge in the industry, and backed by Samson with technical support, great products, and timely delivery. All of which was proven to benefit NAD and their client when they needed it the most.
KEY BENEFITS
The key benefits to using Samson AmSteel®-Blue for lifting slings include:
- Maximum strength-to-weight ratio
- Size for size, it is as strong as wire
- It is easy to handle
- It is safer for crews overall
The benefits of working with Samson’s distributor network include:
- Stocked shelves
- Splicing fabricators on staff
- Fast turnaround
For more information visit www.SamsonRope.com.
