Arctic Offshore Materials And Platform Winterisation

Hauge, Mons (Statoil)



Materials for fixed and floating structures in arctic environment must be designed for low ambient temperature. The offshore operating environment is also including sea ice, marine ice accretion and snow. The materials strength, ductility and wear resistance are challenged. Structural steels and steel for piping and pressure vessels for operating temperatures down to -60°C are needed, and the steel industry has a challenge to meet such requirements. At the same time the testing and qualification procedures should be improved to open for utilisation of new materials and welding procedures. As operation in many cases is located in remote areas, the cost of maintenance and repair is more expensive, and the need for replacements, repair and maintenance should be minimised. Of particular importance is the corrosion protection by painting and cathodic protection. The integrity and performance of the process system depends upon a good control of the temperature in the production and utility fluids. Therefore, insulation and electrical heat tracing of piping and process equipment is essential. The material selection must therefore take into account that large temperature variations can take place and that the maximum temperature associated with localised heating can be higher than normal process temperature. Operation of gas production systems includes strict requirements to ventilation. Natural ventilation is not compatible with enclosed process systems unless very large ventilation systems are installed. Material selection for advanced heating, ventilation and air conditioning (HVAC) systems and combinations of natural and mechanical ventilation systems need to be developed for systems operating in arctic marine environment where sea spray, ice accretion and snow can cause problems. Ice repellent materials are attractive, but the long term performance of the materials is questioned. The lecture will review the state-of art on these items and propose some ideas on the way forward.