The accidental release and ignition of flammable vapours in petrochemical facilities generate overpressure and drag load which can impact the safety of installation and people. The intensity of the BLAST loads depends on many influencing factors including congestion, geometry, type & amount of fuel, leak size, and points of ignition among others. Given the stochastic nature of these parameters, it is obvious that the design for accidental load must be determined using a probabilistic method. This paper discusses a methodology known as “explosion exceedance diagram” and draws on recent developments in vapour cloud explosion research to determine the design accidental load (DAL). A case study demonstrates the application of the method.

Most of oil and gas OFFSHORE PLATFORMS are located in the seismic regains. Therefore, Seismic vulnerability evaluation of the OFFSHORE PLATFORMS is one of the essential vital issues in the structural systems. In this article, jacket type OFFSHORE PLATFORMS are examined by incorporating the pushover analyses and nonlinear time history analyses, in such a way that, first some push over analyses are performed to detect the more critical members of the jacket platform in consonance with the range of their plastic deformations. Subsequently, nonlinear time history analyses are performed, concentrating on the critical members, to examine the vulnerability of the jacket platform under intensive earthquake loads. Pursuant to the numerical results, the combination of the push over analyses and nonlinear time history analyses proposes a reliable and swift seismic assessment procedure to evaluate the seismic vulnerability of the OFFSHORE PLATFORMS. Moreover, seismic vulnerability of the OFFSHORE structures is dependent on the critical member locations and their load bearing situations in the OFFSHORE structures.

Lift installation of a major marine or OFFSHORE structure necessitates detailed evaluation of inter-dependent engineering and construction constraints that influence the feasibility, safety and cost-effectiveness of the lifting operations. Due to the advancements in heavy lift technology, large modularized ship blocks may be fully outfitted, and then lifted and joined to form the entire ship. Similarly, an OFFSHORE structure may be fabricated in a yard, transported to the selected OFFSHORE location, and then installed by lifting. The objectives of this paper are to find the locations of optimum positions of OFFSHORE platform heavy lift points using the method of evolution strategies either minimizing the moment or maximizing the natural frequency. The results obtained are compared with the published results. The optimal positions of simple supports are located to maximize the fundamental frequency of beam or plate structure taking into account both elastic and rigid supports. The minimum stiffness of a simple support (or point) that raises a natural frequency of a beam to its upper limit is investigated for different boundary conditions. The solution also provides insight into dynamics of a beam with an intermediate support for more general boundary conditions.Finite element approach is used for solving the problems. The computer packages such as PREWIN/FEAST, SAP90 are used for performing finite element analysis.