Abstract
Traditionally, F&G detectors are positioned based on engineering experience, industry practices, or prescriptive standards. In recent years, Fire and Gas Mapping (F&G Mapping) studies which utilise 3D based computer aided mapping tools have been recognized as an effective way for Fire & Gas detection system design. Such a study has the advantage of quantified detection coverage to ensure prescribed performance targets are met and deliver optimised Fire & Gas detector layouts.
In the Oil & Gas industry, the most widely adopted F&G mapping assessment guidelines are BP GP 30-85 and SHELL DEP 32.30.20.11. Comprehensive F&G mapping requirements are described in these guidelines including: Risk grading of the fire and gas detection areas; Target fire and gas cloud sizes associated with the risk grade; and Performance coverage requirement (i.e. target coverage percentage) associated with the risk grade.
The BP guideline adopts the risk based mapping requirements, i.e. fire and gas detection zones are classified as different categories (high / normal / low fire risk areas, fully-enclosed / partially-enclosed / open areas based on congestion and blockage), and corresponding target fire and gas clouds of various sizes and target coverage percentages are assigned, in order to provide more cost-effective solutions to deploy the F&G detection systems. The SHELL guideline adopts a similar concept in gas detection by differentiating the target cloud sizes based on the congestion and blockage level of the detection areas.
A more recent challenge in the industry involves cost-effective project delivery through F&G mapping assessment to cater for two major concerns:
Assurance of safety performance of the F&G detection system, i.e. provide adequate detection coverage; and
Optimization of the F&G detection system to minimize CAPEX and OPEX.
The above trend requires improved F&G mapping calculations to reflect the actual performance of the F&G detection systems, meanwhile, taking into consideration the actual scenarios in fire & gas release events thus leading to further improvement of the risk based F&G mapping approach for performance evaluation. A consistent strategy for conducting F&G mapping studies at various project stages is also essential to minimize the discrepancies in conclusion due to changes in different engineering design stages.
This paper illustrates cost effective solutions through risk based approach F&G mapping study developed by ERM following completion of numerous F&G mapping projects. The paper also presents improved approaches to F&G mapping when evaluating the F&G detection system effectiveness.
