This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 26579, “Passive-Fire-Protection Optimization in Offshore Topside Structures,” by Ali Sari, Genesis Oil and Gas; Ekkirala Ramana, Technip Malaysia; and Sepehr Dara and Umid Azimov, Genesis Oil and Gas, prepared for the 2016 Offshore Technology Conference Asia, Kuala Lumpur, 22–25 March. The paper has not been peer reviewed. Copyright 2016 Offshore Technology Conference. Reproduced by permission.
Applying sufficient passive fire protection (PFP) on topside structural-steel members is critical. Simplified and conservative approaches are available to estimate the extent and amount of PFP necessary. The main concern with simplified approaches is that they can lead to overapplication of the PFP, resulting in substantial increase in topside weight. These methods also may result in underestimation of the required amount of PFP, which can compromise structural integrity. This paper presents a risk-based approach for PFP-scheme development.
The structural-integrity assessment and fire-response analysis of offshore plat-forms in fire focus on providing safe escape routes for personnel for a specified period of time and minimizing the probability of damage and fracture in primary structural steel, hydrocarbon-equipment supports, secondary steel along the primary escape routes, and pressurized hydrocarbon pipes and vessels.
In order to achieve this, PFP is used extensively in offshore topside structures. A PFP material is a good thermal insulator, and application of PFP on steel components of the topside structure results in a delay of the heat transfer to the protected members. Therefore, material degradation and thermal expansion are postponed in protected members. Consequently, structural integrity of the escape routes and safety of hydrocarbon pipes and vessels can be retained for a specified period of time, depending on the rating of the PFP material (properties and thickness). On the other hand, if PFP is used excessively, a considerable amount of cost will be imposed related to PFP material, installation, inspection, and maintenance and a considerable amount of dead load will be added to the structure. Therefore, investigations on the optimal application (e.g., choosing the right places—members, joints, vessels, and pipes—along with the right material in the appropriate thickness) in offshore platforms can result in cost-effective use of PFP while still achieving the purpose of the PFP application.
Existing PFP-Optimization Approaches
Global Fire (Individual-Member Failure). The global fire analysis method for identifying PFP application on a top-side structure requires analysis of the whole structure when entirely exposed to the most severe fire loading. The PFP scheme is then developed on the basis of the structure’s response. This method is very conservative and results in an excessive amount of required PFP to resist the fire loading.