Increasing the tension

Elaine Maslin

May 1, 2015

Maritime Developments, based in Peterhead, Scotland, has released its first four-track, 75-tonne pipeline tensioner, not long after shipping out the third of a 50-tonne version of the unit, which took center stage at Subsea Expo in Aberdeen in February.

Maritime Development’s four-track, 50-tonne tensioner. Photos from Maritime Developments.

The firm, set up 15 years ago, sold its first TTS-4/140 Series, 50-tonne, four-track pipelay tensioner in 2013. The design was patented in July 2014, ahead of the 75-tonne version unveiling earlier this year.

The four-track caterpillar track system for installing or recovering pipe, flexibles, umbilicals and cables in two- or four-track mode has been designed so it can be used horizontally, hung off vertically, or on a ramp, as well as containerized for shipping. In horizontal mode, one of the 4m-long tracks can open to load pipe, maintaining one track at the base to centralize the load. In horizontal mode, which can be harder to load pipe due to vessel motion, but it is no longer necessary to have a centralizing track, two of the tensioner’s tracks can open out to load pipe, which may have end termination pieces on it.

The V-shaped caterpillar tracks grip the product with failsafe hydraulic cylinders. The maximum pull force is rated at 51-tonne in four-track mode (0.09 coefficient of friction), and 25.5-tonne in two-track (0.09 CoF). Payout speed on 50-600mm outer diameter product varies up to 900m/hr (at 60Hz) with 10-100% digital tension control.

Derek Smith

Derek Smith, the firm’s CEO, started out in the fishing industry, building winches for fishing vessels and providing port services, but diversified into the oil and gas sector, and now provides back-deck equipment including winches, tensioners, and reel drives, mostly serving the <150-tonne line pull market place, in <500m water depth, acknowledging that the market above that level is already well served. By July this year, the firm will have supplied a full back-deck spread to one vessel.

In some areas, the industry could learn from fishing, he says, especially around control systems. “Operating systems on fishing vessels are very sophisticated,” he says. Fishermen put acoustic devices on their nets which transmit to a transducer on the hull, the signals from which are then used to automatically control the geometry of the nets by control tension. Smith thought this could be used in the industry, on equipment which didn’t have accurate constant control systems, by floating equipment on load cells, with the operator just dictating what he wants the system to achieve. The firm has developed its own software, in-house, for its systems.

The 75-tonne tensioner with one track opened out for loading product.

While the fishing industry systems are sophisticated, they are built to be robust and easy to use, with simple interfaces and reduced decision making requirements, whereas in the offshore industry the systems need more technically adept staff to operate them, Smith says.

The business recently secured the first order for a portable overside vertical lay system (PVLS) from a leading installation contractor. Maritime Developments will deliver a bespoke vertical lay system tower along with a four-track tensioner and a multi reel drive system to support a major North Sea field development.

Maritime Developments has also delivered a 500-tonne reel drive system (RDS) in support of a project in the US. It was the fourth RDS order executed by the business since the product’s launch in 2013: three 400-tonne systems have also already been supplied.