Cable protection

Using expertise developed for the oil and gas industry, Seaproof Solutions has carved out a market in offshore wind.

Seaproof’s J-tube interface. Images from Seaproof Solutions.

In a short period of time, Seaproof Solutions has gone from having zero market share in cable protection systems (CPS) for the offshore wind industry to a 20% market share and growing.

Over the past three years, it has sold some 700 of its systems and, while they’ve proved a hit, the company is hard at work making systems that are even easier, faster and safer to install.

It’s a critical area for the offshore wind industry. While offshore power cable installation isn’t the highest cost segment of wind farm installation costs, it has been one of the more troublesome areas, due to cable damage.

Seaproof, based outside of Bergen, used its 25 years of expertise in polyurethane composite engineering to design a solution for seismic cables as well as applications in the defense and research sectors.

It is a modular system created from sections of hard, fiber reinforced polyurethane tubes, a monopile interface unit, a ventilated section where the cable in the tube is out of the water, with pull-in head, and hang off connector interfaces. These can be pre-installed offshore, ahead of cable pull-in, or installed as part of the cable pull in – with both methods protecting and reducing stress on the power cable.

The system has been designed without need of ROV intervention or a diver, and has been deployed with installation times of just 30 min achieved on some projects.

Seaproof’s CPS.

“This type of application didn’t exist in oil and gas, so something new had to be designed,” says David Vallee, technical sales and key account manager, Seaproof.

The CPS addresses concerns around stress points, where cables enter and hang off offshore wind turbine structures. In many, there’s a pre-made 34cm-diameter hole in the foundation, about 2.5m from the seabed, into which the cable is pulled through. It then hangs from this hole, creating a free span out to the burial point, which means there are significant stress points, during and after the pull-in.

Seaproof’s fiber reinforced polymer tubes have monopile interface units that allow the cable end to be pulled in through the hole, using a messenger wire, and up into the turbine, without the cable being exposed, put under stress or strain.

The system, which is flexible and strong, is pre-installed on the cable, either on the quayside or on deck, surrounding a section of the pull-in end of the cable. It is then pulled up into the turbine hole. Once the monopile interface section reaches the hole, it locks in place under tension, then releases the cable to run free up into the turbine to its termination point.

The system comes in 4m-long sections, which are connected to create what are usually 20-25m-long systems, but can be up to 60m, says Vallee.

One of the benefits of using fiber is the ability to create end connections that can work with steel work, something which has been difficult for other technologies, says Vallee. Seaproof has a patented system to allow this, which is also used to connect the 4m sections. Small steel flanges connect the sections with fiber running between each flange, which creates a rib-stop net preventing breaks and effectively stops cracks in the polymer.

But, Seaproof is not resting on its laurels. The push to reduce costs in offshore wind is as hard, if not harder, than in the current oil and gas market. Some cost reduction can be made by making operations simpler and by doing them onshore, before offshore work starts.

Seaproof has designed a new, diver and ROV-less system, which is a little like a J-Tube. The pre-installed CPS, into which the cable is pulled-in through a wide opening at the bottom.

But, now that Seaproof has developed these systems for renewables, the firm is looking at introducing similar technologies into the oil and gas industry, although not in exactly the same form.