Further Weight and Cost Saving of Fire and Blast Resistant Walls on Offshore Installations, Through the New, 4th Type and a Comprehensive Decision Making Model

Abstract

Abstract This paper presents an overview of 50 years of development of fire and blast resistant walls for offshore installations and introduces the fourth generation or "Type" of wall. This thoroughly tested and certified 4th Type was developed as a response to the continuous quest to further optimise the cost and weight of offshore topsides, thus allowing operators and designers to accommodate more equipment and higher field yield. Inductive research indicates that the selection of a fire and blast resistant wall design amongst the available Types is very often biased and predominantly based on past experience. As such, the traditionally selected option has been a monocoque structural design incorporating load bearing walls instead of framed construction designs with non-load bearing infill walls. This bias can lead to sub-optimal design and execution of offshore installations. This paper reflects on 4 Types of offshore fire and blast walls. From the 1st Type, derived from the shipbuilding industry up to the 4th Type, initially used on recent offshore wind HVDC transformer platforms and more recently also on the oil and gas platforms as a response to the continuous need to reduce weight and improve on safety. This 4th Type, with a weight of just 25 kg/m2, is certified as capable of withstanding up to 2 hour hydrocarbon fires and has been tested with a considerable free span. In this paper, all 4 Types of walls are assessed against a limited series of hard and soft performance criteria, according to a decision making model which can be used to select the fittest-for-purpose Type of wall system. This model includes the distinction between internal fire walls, external fire walls and external fire and blast walls.Table 1Offshore fire wall comparison table – core criteriaOffshore fire wall comparison tableCriteria:Wall Type:Type IStressed skinType IICorrugated skinType IIIBuilt-up wallType IVPrefabricated sandwich constructionWeight100%60%45%35%Installation time100%70%60%15%Overall cost100%80%60%40%Installation time for wall penetrations100%100%40%30%