Petrobras has been monitoring the benefits of polymer-based fire-protection products devised by Trellebrog Offshore, part of the Trelleborg Engineered Systems group. Engineers from the Brazilian oil company recently visited the Trelleborg Viking plant in Norway to find out about reinforced rubber drain gullies for use on FPSOs.
During the visit, they observed a fire test in which a section of drain gully was subjected to a jet flame with a temperature of over 1,100°C (2,012°F) for two hours, after which it was still intact.
Petrobras’ interest has been sparked by safety concerns over the sliding metal plates that currently are used to absorb movement on the company’s FPSOs. “They bend as the ship moves with the waves, and they suffer structural tensions,” one of the company’s engineers told the Trelleborg journal.
Trelleborg’s Merete Rønningen inspects one of the drain gullies on Marathon’sAlvheim FPSO.
“There is a lot of movement between the modules on an FPSO, and if you use plates to form the gully, they push against each other and may break,” confirms Merete Rønningen, project manager for Trelleborg Viking. “Rubber drain gullies can absorb the movement without losing their shape. They are also fire resistant, with an H60 fire rating, and can withstand jet fires.”
The gullies play an important safety function by draining spills of hydrocarbons off into safe storage, and in case of fire, by collecting burning fluids without losing their integrity.
Trelleborg Viking’s drain gullies have been supplied to Statoil’sNorne FPSO and Kristin semisubmersible production platform, ExxonMobil’s Jotun FPSO, Woodside’s Laminaria FPSO, and Petro-Canada’s TerraNova FPSO.
The latest delivery is to Marathon’sAlvheim ship in the Norwegian North Sea. This order amounted to 300 m (984 ft), including not only four gullies between modules where they interface with a high vertical seal, but also the drain running the length of the pipe racks.
OnAlvheim, the drain gullies interface with flexible seals, also provided by Trelleborg Viking. Such seals offer a flexible connection capable of absorbing large displacements between rigid steel sections; Trelleborg has supplied deliveries previously to the Jotun and TerraNova vessels, to BP’s Schiehallion and Statoil’s Åsgard A FPSOs, to Statoil’s Kvitebjørn platform, and for SEIC’s Sakhalin II project.
In addition to their fire resistance, which is much higher than that of steel, Trelleborg’s drain gully and seal products can withstand blasts of up to 2.1 bar (0.21 MPa) and high impacts, are unaffected by contact with hydrocarbon fluids and seawater, and can be used in a wide range of operating temperatures. They also have a 30-year design life.
For more information, contact Merete Rønningen, Trelleborg Viking. Tel +47 3223 2000, fax +47 3223 2200,[email protected], www.trelleborg.com/viking
