Dr. Yngve AnderbergNorsk Hydro's Visund project is the latest on which Fire Safety Design has been contracted to bring its expertise in fire protection to bear. The company is a leader in the development of computer analysis to optimise passive fire protection requirements, and has delivered cost savings to offshore installations in the North Sea and elsewhere.
Fire Safety Design
For the Visund project FSD will use its Global Collapse Analysis program to optimise the passive fire protection applied to the drilling derrick, in order to ensure that in the event of fire, the structure will maintain its integrity for a minimum 10 minutes; and that, if or when it does collapse, it falls in a pre-planned direction and not on top of, for example, the accommodation module.
FSD has already carried out the same analysis for Norsk Hydro's Njord platform, and director Dr Yngve Anderberg sees the new contract as a vote of confidence in the quality of the company's work. "I believe we are the company with the widest experience in optimising passive fire protection," he says. Typically the amount of insulation can be cut by up to two thirds compared with the amount calculated by methods conventionally used by the offshore industry such as the form factor method.
A example is the calculation of the coat-back distance, the distance over which a secondary steel member welded into a primary, load-bearing structure must be fire-protected in order to prevent significant heat transfer from the former to the latter in the event of fire. Where the rule of thumb used by much of the industry would indicate the need for a coat-back distance of between 450mm and 750mm, FSD's calculation, which takes into account variables such as the heat load level, fire duration, and size and configuration of the secondary member, would typically be 150-300mm. For the operator this means savings in the amount of insulation material required, in the weight and in future maintenance needs, which are vital issues.
The company also helps to cut project costs by simulating fire tests, and thus reducing the number of tests that actually have to be carried out to a minimum. Moreover, the combination of simulation and actual tests itself enables the amount of insulation to be reduced by 25-30% compared with using fire tests alone, Anderberg says.
With its deep knowledge of fire safety, FSD has produced a design guide for passive fire protection which gives a ready indication of the amount of insulation needed. DNV accepts the guide for general use offshore in the North Sea , but Lloyd's Register wants the company to undergo the expensive process of having its software certified as a prerequisite for accepting the design guide. Anderberg, however, says that a more satisfactory solution would be to have the company certified, a proposal he plans to put to LR.
Increased sensitivity to safety in the offshore industry following the Piper Alpha disaster in 1988 raised the demand for FSD's services and its profile. The breakthrough came with a contract for the Snorre TLP project, Anderberg says. FSD performed optimisation of passive fire-proofing on the steel in well-bay areas, risers and the TLP columns, and on aluminium in the living quarters. Its work resulted in savings of 70 tonnes of insulation, worth $2 million, in the well-bay area.
For more information contact Dr Yngve Anderberg, Fire Safety Design: telephone +46 46 14 00 20 or fax +46 46 14 00 30.
