Blast and Fire: The Engineering Background
Authors: Tolloczko J.J.A. 
Published: October 2008

This paper gives a general overview of explosion and fire engineering as applicable to offshore structures. The subject is very complex and relies on a wide base of expertise vested in both the scientific and engineering disciplines to develop an understanding and the technology to construct blast and fire resistant structures. This paper, by the very nature of the subject, can only give the reader a general introduction. Other papers at OTC 1991 discuss in more detail some of the technical areas addressed in this background paper.

It is also important to point out that this paper assumes that a release of hydrocarbon will occur and that the probability of ignition is one. It does not consider the primary safety measures which should be adopted such as prevention, human awareness and training, operation and quality systems, optimizing reliability or minimising risk. The paper is based on the premise that should an incident occur the surrounding structure should retain its integrity or containment capability so as to allow human intervention to counteract the incident or at the extreme condition to allow the evacuation of crew. With this in mind the paper discusses the following four areas; Blast Loading Fire Loading Blast Response Fire Response In addition the paper reports on the status of the Joint Industry Blast and Fire Engineering Project for Topside structures.

INTRODUCTION

In recent years it has become apparent to the offshore industry that a major gap exists in the understanding of how a hydrocarbon explosion and/or fire would behave on an offshore facility. This understanding is necessary if the solutions adopted, for either the containment of such an incident or the maintenance of the facilities integrity, are to be implemented with confidence. The problem facing the industry is the proximity of extremely congested hazardous areas and highly populated living zones. An additional complication is the location of the facility which is situated in a harsh sea environment with no method of instantaneous mass evacuation of personnel.

The World offshore Accident Databank WOAD [maintained by Veritec of Norway], records that during the last 19 years 1150 workers have lost their lives in offshore accidents, and that 125 offshore platforms were totally destroyed, while 533 fixed and mobile units suffered severe or significant damage. It is certain that many of these statistics exist as a consequence of explosions and fires.

The consequences of such an incident not being contained is therefore obvious. It is hence imperative that all possible realistic measures, based on the current level of knowledge, are used to prevent an incident escalating into a disaster.

This paper therefore gives some general background information relating to explosion and fire engineering and also describes how the industry is responding by collaborating in the development of technology.

TECHNICAL BACKGROUND

On an offshore complex, natural gas or liquid hydrocarbon (or a combination of both) 1s extracted from a reservoir, via a riser onto a well-head platform or wellhead module/area.