Determining the optimal distance between explosive, flammable, and toxic hydrocarbon sources and occupied structures is a constant concern for engineers working to design safe facilities. Over the years, many incidents have occurred during which workers were injured or killed by flying shards of glass and debris, explosive forces, fire, or exposure to toxic gases when occupied structures were not located properly in relation to process equipment. This paper presents newly developed techniques to allow the engineer to locate occupied structures optimally to ensure that the risk of harm to personnel is minimized.
The analysis of determining the placement for an occupied structure involves many variables that the engineer must evaluate. These variables include the properties of the hydrocarbons that are being processed, toxic components (e.g., hydrogen sulfide), operating parameters, loss-of-containment scenarios, prevailing winds, occupancy loads, building construction, safety systems, and operating and maintenance practices. Each of these different variables can have a significant impact on where a building should be located within or adjacent to a facility. The engineer must consider these variables for impacts to the structure caused by fire, blast, or toxic-gas infiltration.
Recognized industry best practices and regulatory requirements require that blast loads, which commonly present the most-severe hazard to a building, be evaluated when locating an occupied structure. Often, it is not practical to design or locate a building to withstand the “worst-case” blast scenario. For this reason, a risk-based approach, in conformance with recognized best practices, has been developed to site buildings properly at oil and gas facilities.
This paper presents a viable risk-based approach for the siting of occupied structures at oil and gas facilities. The technique presented in the paper enables the engineer to gather the information needed for the analysis quickly, evaluate credible scenarios, and then make the necessary calculations to determine impacts to the occupants. The result of using this technique is that an occupied structure is located properly and constructed to reduce the risk of harm to the occupants to a tolerable level.