Enormous time savings during assembly of cable carousel in South Korea
If you have to assemble and dismantle a cable carousel with 6,000 bolted joints size M56 multiple times, the nut runners from RAD are a very welcome addition. At Evers Staalconstructies BV, the traditional hydraulic torque wrench was largely replaced for a significant part of the work by the E-RAD, an electric powered torque wrench from RAD. And that saved many hours of tightening each time. Technician Dennis Seijsener knows all about it.
Evers Staalconstructies BV in Hillegom has existed for over 80 years and is an important partner for a wide range of clients, including the offshore industry. Thanks to high-quality craftsmanship, the company has now won four national and one international steel awards. Nowadays, Evers Staalconstructies is part of a group of cooperating steel construction companies, each retaining its own identity. Thanks to high-quality craftsmanship, the company has now won four national and one international steel awards. Nowadays, Evers Staalconstructies is part of a group of cooperating steel construction companies, each retaining its own identity.
Carousels
For about two years now, Evers has been building a series of heavy cable carousels for offshore use, applied in laying, among other things, communication cables on the seabed. The assignment to develop and produce these came from a Norwegian offshore company specialized in subsea constructions, pipe-laying vessels, and fast support vessels. The carousels, with a capacity of up to 4,000 tonnes, are rented out to cable-laying companies that install them on specially equipped vessels.
While more carousels are rented in the offshore world, this one is unique due to its modular construction. The carousels are delivered worldwide in parts using 40-foot containers and can be assembled within a few weeks.
A repetitive job
For all these carousels, Dennis Seijsener has been closely involved as supervisor/technician in both on-site assembly and dismantling. This was also the case in South Korea, where he was recently involved in assembling a carousel capable of carrying no less than 4,000 tonnes of cable, a so-called 4,000-ton carousel. To give an idea of the scale: the average cable has a diameter of approximately 200 mm and weighs between 80 and 100 kg per meter. A 4,000-ton carousel can carry approximately 50 km of cable.
“It started with a small 1,250-ton carousel,” Dennis explains, “but it didn’t stop there, because after that we received an order for a 2,000-ton and twice a 4,000-ton version. And the 1,250-ton unit was gone for a year, then converted to 1,500 tonnes and later to 3,000 tonnes of cable. And now it’s located in Eemshaven. It really is a unique but fascinating world.”
At the client’s request, Dennis is specifically responsible for assembly and dismantling. After engineering and production, a carousel is first fully assembled at the company in Hillegom, then test-run, and afterward the construction is dismantled again and shipped in parts by container. Once it arrives at its destination, the construction is reassembled, filled with cable, and placed on the subframe on the vessel.
“For assembling a 4,000-ton unit, weighing 650 tonnes of steel construction, we were busy for about six weeks until recently—with assistance from a technician from the client,” he explains. “For assembling a 4,000-ton unit, weighing 650 tonnes of steel construction, we were busy for about six weeks until recently – with assistance from a technician from the client,” he explains.
“For assembling a 4,000-ton unit, weighing 650 tonnes of steel construction, we were busy for about six weeks until recently—with assistance from a technician from the client,” he explains. “For assembling a 4,000-ton unit, weighing 650 tonnes of steel construction, we were busy for about six weeks until recently – with assistance from a technician from the client,” he explains.
RAD Torque Systems comes into view
When asked how they came to use RAD torque wrenches for assembly and dismantling, Dennis explains that a good business relation saw the E-RAD at a trade show and immediately became very enthusiastic. That enthusiasm quickly transferred to him as well. “We were still working with hydraulic torque wrenches, which is fine in itself, but it is not the fastest method. Each time, one click further, and tightening a joint of 12 bolts M56 to torque took me about 1.5 hours. When we tried that with the E-RAD, the job was completed in about 12 minutes.”
One and a half hours or 12 minutes—it is clear that with a complex steel construction such as these large carousels, where approximately 6,000 bolts must be tightened to torque, enormous time savings are achieved with the E-RAD. “The big difference is, of course, the working speed, but in addition it is much easier to work because you only have the torque wrench with you, which also has a pistol grip. Just like a drill, so to speak.”
An additional advantage he experienced is that the bolts do not rotate as easily during tightening. “With hydraulics, you rotate a small amount each time, and the bolt tends to rotate along. The RAD continuously tightens the nut in one motion, so the bolt head grips better and the joint is tightened more easily.”
1,000 bolts per day
During assembly and dismantling of the carousels, two RAD torque wrenches are used, a 4,000 and an 8,000 Nm, and with these an average of 1,000 bolts are tightened to torque per day. For hard-to-reach locations, Dennis still uses a hydraulic torque wrench. “The RAD doesn’t fit everywhere. They do have a model with an angled head, but it does not have sufficient capacity; we cannot achieve the required torque values with it.”
He was also impressed by the enormous power of the RAD torque wrench. “Incredible. And precisely because it is an electric powered device, you wouldn’t expect it. But it just keeps going.”
In short, Dennis Seijsener is very positive about the E-RAD. “We did the first carousel frame hydraulically. Then we briefly tried air, but that didn’t really work, and after that with the RAD. Well, I was convinced immediately.”