Freefall: Adhesive helps composite lifeboat achieve world record
Used for rapid evacuation from oil and gas rigs and offshore installations, freefall (FF)-class lifeboats must now conform to the revised Det Norske Veritas (Bärum, Norway) DNV-OS-E406 standard to ensure that they will survive launches from the greater heights and in the extreme weather/sea conditions they will see as offshore facilities grow in size. A composite FF lifeboat built by Umoe Schat-Harding Equipment AS (Schat-Harding, Rosendal, Norway) successfully endured the 65.1m/213.6-ft drop test now required and, in the process, set a new world record for the highest lifeboat freefall.
The FF1200 model used in the test features cored fiberglass sandwich construction in the hull, top section and canopy. To improve its impact resistance, Schat-Harding used Crystic Crestomer 1152PA urethane acrylate structural adhesive supplied by Scott Bader Company Ltd. (Northhamptonshire, U.K. ) to bond bulkheads, hull stringers, composite interliners and the canopy to the hull. Automated bulk dispensing equipment and pneumatic handheld guns helped to achieve the required higher production rates.
Scott Bader reports that the pre-accelerated, MEKP-catalyzed 1152PA adhesive fills gaps as wide as 25 mm/1 inch, with a gel time of 50 minutes at room temperature. An alternative, Crestomer 1153PA, offers a gel time of up to 90 minutes for composite sections that have one or more dimensions larger than 25m/82 ft, and/or are processed at elevated ambient temperatures. According to published technical data, Crestomer 1152PA exhibits typical composite-to-composite lap shear bond joint strengths of 10 MPa/1,450 psi, with composite substrate failure — not adhesive failure — as the limiting factor.
For the test, the FF1200 lifeboat was internally loaded with weights (7 metric tonnes or more than 15,430 lb) to simulate its maximum capacity (in special seats with five-point harnesses) of 70 people who weigh an average of 100 kg/220 lb. On impact, the nose section must withstand a force of approximately 45 metric tonnes (99,200 lb), after which the boat fully submerges to a depth of more than 10m/33 ft, and then must be able to resurface and speed occupants away to safety.
The FF1200 is the first FF lifeboat to pass all the new full-scale DNV tests. “We have demonstrated through this new world record,” says Schat-Harding CEO Geir Arne Veglo, “that our FF1200 is the frontrunner in meeting new stringent regulations.”
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