Comparative Analysis of Empirical Gas Explosion Models and Blast Resistant Design of PC Panels

Abstract

Equipment in onshore plants is installed densely and therefore highly exposed to gas explosion. For protection of life and property, blast resistant design is applied to main buildings, but there are no guidelines for design. Major petroleum companies like BECHTEL or BP plc. make their specifications for blast resistant designs based on TNT equivalent mass. Recently, because gas explosions have various results depending on various external conditions, the TNO multi-energy method or Baker-Strehlow-Tang (BST) methods are mainly used. The conditions are considered in the form of the class or Mach number in the TNO multi-energy or BST method, respectively. The class or Mach number is rarely chosen except by some well-established overseas consultancy companies. This thesis studies which class or Mach number of the TNO multi-energy or the BST method corresponds to the overpressure by existing guidelines, which are based on the TNT equivalency method. The different overpressure, duration, and impulse of three methods are analyzed. The various design results by these methods are also researched. Based on the studies, overpressure of the most conservative guideline – the explosion by 1 ton of TNT at a distance of 100 ft. (30.5 m) – has the class number between 6 and 7 or the Mach number between 0.7 and 1.0. When the three methods predict the similar overpressure, the TNT equivalency method provides the shortest duration and smallest impulse. The overpressure by the TNT equivalency method decreases with increasing distance. The higher class or Mach number has shorter duration and larger impulse. When these methods are applied in blast resistant designs based on this scenario, the TNT equivalency and the TNO multi-energy methods predict the largest and smallest overpressure, respectively. Two response parameters, ductility ratio and support rotation, are used to check design. When blast resistant PC panels are checked, the TNT equivalency, TNO multi-energy and BST methods predict ductility ratio as 10.5, 0.82 and 25.2. Predicted support rotation is 5.1°, 0.4° and 11.5°. Based on these criteria, this wall design only can be passed as evaluated by the TNO multi-energy method. When blast resistant PC panel connections are designed, the ratio of required connection is 3:1:2

TNT equivalency, TNO multi-energy, BST method. These studies show different results when different gas explosion methods are applied on blast resistant designs. Many domestic engineering companies still use TNT equivalent mass for blast resistant designs. As plant design orders of other countries increase, it may be anticipated that research about the TNO multi-energy and BST methods is needed. Because this thesis suggests the relation the TNT equivalency method and the TNO multi-energy or BST methods and shows the different results generated by each, it can help engineers who do blast resistant design with these methods.