SELECTION OF ENVIRONMENTAL PARAMETERS FOR OFFSHORE JACKET PLATFORM DESIGN IN MALAYSIA

Steel jacket platforms are the major type of platforms used for offshore Malaysia for water
depth from 45 to 80 meters. Worldwide platforms are designed API (LRFD & WSD). The
parameters in these codes for Gulf of Mexico (GOM) and North Sea are much higher due to
severity of weather. Since this is not true for Malaysia, these parameters need to be
evaluated. This work examines what changes can be made in this regard for future design
in this country. The jacket platforms in Malaysia are being designed as per API WSD. The
weather conditions in Malaysia are different compared to GOM. The load factor used for
environmental load by API and ISO code for extreme event is 1.35. Data for this region
needs to be analyzed so that proper reliability based load factors can be developed for this
region. For this, the environmental parameters for extreme conditions (100 year) and
normal conditions (1-5 year) are considered. Offshore fields in Malaysia are spread over
three regions. Wind is measured at 10 m elevation and standard time interval is 1h. To
collect data for waves, the stable sea state is taken as 3hour time period. For the design of
offshore jacket platforms, global forces from wind are not as important as those which are
caused by waves and currents. The ISO recommends the use of 10 minute average mean
wind for overall structural analysis and 3 second gust wind speed for design of individual
component. The significant wave parameters for single, periodic design wave are height,
crest elevation above MSL, period and direction.