Allseas

Allseas is a contractor in the global offshore energy industry, delivering engineering and construction solutions built around subsea pipeline construction and the transport, installation and removal of offshore facilities. Its activities cover offshore pipelay for natural gas, oil and carbon capture; platform decommissioning by single-lift removal of the heaviest offshore facilities; platform transportation and installation for the largest and heaviest offshore structures; polymetallic nodule collection, recovering nodules from the ocean floor; and nuclear, aimed at powering energy-intensive offshore vessels and onshore industry. Scopes include design, engineering, procurement, fabrication and project management alongside offshore execution. Pipelay is the foundation of the business. Allseas uses the S-lay method, named for the shape the pipe takes between vessel and seabed, in which single steel joints are welded, inspected and coated in a horizontal firing line on board before the pipeline exits the vessel and curves down to the seabed. The overbend is supported by a stinger, a steel structure with rollers that prevents buckling, and the sagbend is controlled by pipe tensioners, caterpillar tracks that grip the pipe. The company states it has installed over 30,000 kilometres of subsea pipelines worldwide across more than 340 projects, and describes over four decades at the forefront of offshore pipeline construction. The fleet is designed in-house. Named vessels include Solitaire, Audacia, Lorelay, described as the world's first DP pipelay vessel, plus Oceanic, Fortitude, Sandpiper, Calamity Jane and Pioneering Spirit, with the cargo barge Braveheart added recently. Equipment is developed internally too: a motion-compensated heavy lift system for installing and removing platform facilities, fully automated welding, line-up and inspection systems, field joint coating systems for corrosion protection, and customised subsea construction, inspection and intervention tools. Project examples show the range and geography. They include Atapu-2 and Buzios-10 in Brazil, the YongAn and TungHsiao gas pipeline in Taiwan, Trion and the Sparta export pipelines in the Gulf of Mexico, Troll Phase 3 and Yggdrasil in Norway, Malampaya Phase 4 in the Philippines, the Barossa Gas Export Pipeline and Darwin Pipeline Duplication in Australia, Greater Tortue Ahmeyim offshore Mauritania and Senegal, the Porthos carbon capture and storage pipeline at the Port of Rotterdam, Nord Stream 2, TurkStream and the Sur de Texas-Tuxpan pipeline in Mexico. Decommissioning work includes the Gippsland EPR job, removing ten platforms with a combined weight of more than 48,000 tonnes. Allseas frames its sustainability commitments as minimising environmental impact, facilitating the energy transition and enabling clean waters, and organises its own workforce around construction, design and engineering, operations, offshore, business support and project management disciplines.