(71h) Why Do We Still Have Blast Walls on Offshore Platforms?

The objective of this paper is to step back and think why we still have stand-alone blast walls in the design of offshore platforms.   Blast walls are reactive mitigation protection required if there is an explosion over pressure concern that can jeopardize the escape and evacuation of personnel off the platform.  It is interesting to see that it has become common practice to install this mitigating protective system during conceptual phases of platform development rather than putting effort in reducing the potential and magnitude of potential hydrocarbon accidental releases as per international guidelines such as the UKOOA/UK HSE “Fire and explosion guidance – Part 1: Avoidance and mitigation of explosions”  - Issue 1 (2003) Table 2.1  or API RP 2FB – “Recommended Practice for the Design of Offshore Facilities Against Fire and Blast Loading” and ISO 13702 –“ Petroleum and natural gas industries – Control and mitigation of fires and explosion on offshore production installations – requirements and guidelines”.   This paper will be based on the authors experience and lesson learned during the design of offshore installations utilizing Computation Fluid Dynamics (CFD) explosion modeling, at the pre-conceptual stages of a platform development project, as a design tool, in the decision for the final layout of the facility. The concept of an inherent safe approach to a design will be explained in parallel to how this approach affect the inputs to the final quantitative risk analysis study that is performed during most of the current offshore facilities design.  This process or approach is utilized as a means of demonstrating “As Low As Reasonably Practicable – ALARP) in some regulatory regime.  The intent of this paper is to have practitioners step-back and review how blast walls are justified during a conceptual design phase of an installation development and realize that a focus on a better understanding of this explosion overpressure hazard mechanism, early in a project life cycle will provide a more cost effective & safer design and operations of a platform.  It must be reminded that the key is in minimizing the loss of containment to improve the production availability of a producing facility and thus the use of an inherent safe design process.