Offshore floating exploration and production facilities

Floating exploration and production facilities are sometimes provided on jackup rigs, semi-submersible vessels or ex-crude oil shipping tankers converted to production treatment vessels. These facilities are essentially the same as fixed offshore platform or installations except they are moored in place or provided with a temporary support structure instead of provided with fixed supports to the seabed. The major process fire and explosion risks are identical to the risks produced on offshore platforms. They have one addition major facility risk, that is the maintenance of buoyancy of the installation. Should fire or explosion effects cause a loss of buoyancy (or even stability) the entire facility is at risk of submergence. Adequate compartimization and integrity assurances must be implemented in these instances. 

Siting - The preferred arrangement of bulk transport pipeline systems is for burial underground. This provides for enhanced protection from overhead events. This is even the case for offshore pipelines where there have been numerous incidents of dragged anchors from fishing vessels to pipelines exposed on the seabed. A radius of exposure from a pipeline can also be easily calculated for fires and vapor explosions based on the commodity, pressure, release opening, etc. From these calculations a restricted zone or similar can be designated. 

Isolation - It has been shown that the addition of isolation valves at periodic intervals is not as cost effective as prevention measures such as thickness inspections or tests. However all pipelines should be provided with a means for emergency isolation at it entry or exit from a facility. Offshore facilities may be particularly vulnerable to pipeline incidents as the Piper Alpha disaster has shown. In that accident a contributing factor to the destruction was the backfeed of the contents of the gas pipeline to platform once the topside isolation valve or piping lost its integrity. Further isolation means (i.e., a subsea isolation valve SSIV) were not available. 

Integrity Assurances - When first installed piping systems will be checked for leakages at weld joints and flange connections. Weld joints are usually verified by NDT radioactive means (i.e., x-ray) or die penetrants. 

Depending on the services, the pipeline will usually be hydrostatically or pneumatically tested. Normally a section is specified for testing from flange point to flange point. Once tested the blank flanges at the ends of the section are removed and the tested portions are permanently connected 

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