Authors: S Medonos, Petrellus Ltd, RW Brewerton, Natabelle Technology Ltd, V Jouravel, Rosshelf. Proceedings of OMAE: 21st Offshore Mechanics and Arctic Engineering Conference, June 23-28, 2002, Oslo, Norway.
Recent offshore developments in the Arctic in Russia, the US, Canada and other locations have brought additional requirements on critical systems for safety and environmental protection. The design of the systems broadly follows the design principles for temperate climate. However, a substantial number of key additional requirements exist that are paramount for operations of the systems at down to -45°C and in ice and snow. Equipment reliability reduces with reducing sub-zero temperature. Production, emergency and ancillary equipment have to be heated to prevent the equipment malfunctioning and to prevent the development of upset conditions into hazardous situations. This is valid for both preventative and mitigating measures. The heating has to have a high reliability, should it be HVAC systems or trace heating. A specific focus should be given to material selection, and this not only for operating conditions, but also for transportation and storage where equipment may be exposed to low temperature extremes, which may permanently change the material crystalline structure and its properties.
The extent to which optimum solutions to these problems can be found is often dependent upon the nature of the overall platform layout, especially where designing against major hazards is concerned.
Whole-year protected tunnels are preferred as means of escape, with heating for winter conditions to prevent blockage by ice and snow and ensure high availability whatever weather. They have to be ventilated by highly reliable ventilation systems. A number of fields in the arctic have a very high hydrogen sulphide content, which together with sea and ice conditions sets requirements for special amphibious evacuation craft. Evacuation by means of icebreakers is often not possible for all conditions as icebreaker engines cannot be operated in air with hydrogen sulphide content. A possible solution may be an amphibious survival craft Arktos that has been used to date on some installations.
A great emphasis has in recent years been put on the protection of the environment against operational emissions and discharges, and accidental releases and spills. Whilst the incipient causes of accidental releases and spills are similar to those leading to fire and explosion hazards, recovery from a hydrocarbon spill situation requires specialised equipment with satisfactory performance specific for the Arctic.
Based on the authors’ experience from several recent projects, the Paper presents additional requirements for safety and environmental protection systems for Arctic conditions, addresses incipient causes of equipment and structural failures and it outlines technical solutions for risk reduction, many of which have been used in practice.
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