The design of industrial facilities that use hazardous and flammable materials is a complex exercise. To install such a facility, it is paramount to follow a structured process that requires technical, construction, and management skills. Owners and designers must pay attention to many variables during the design phase. Despite adhering to design norms and practices, achieving a record of lifetime perfect safety is extremely challenging. Industrial accidents do happen - either due to specific control failures or human error. The good news is that over a period of time, many new practices have been adopted as lessons from incidents to make the chemical installations as safe as possible. Still, though safety awareness is improving continuously, it has not translated into avoiding unwanted accidents.
Safety in Design starts from the conceptualization of the facility. The best possible way to achieve safety objectives is to adopt the Inherent Safety methodology. In contrast to traditional practices, where the objective is to control the hazard as it happens, the Inherent Safety mindset seeks to avoid possible hazards completely. However, achieving Inherent Safety is not always possible due to various limitations. But we see an effort in new designs to look for this essential aspect and its implementation.
The way forward is that at the very beginning of a facility conceptualization, one must think of selecting a proven and mature technology that has lower possible hazards. Basic steps like minimizing the inventories of hazardous chemicals and taking advantage of modern communications and logistics must be practiced. Additionally, finding ways to reduce the damaging impact of an undesired event is another step that is important to analyse for Inherent Safety.
Once technology selection is performed based on these basic principles, the project team should aim to implement other aspects of the Safety in Design process and practices. A Safety Philosophy document should be prepared at the project initiation and continued not just for the life of the project execution, but also through the operation of the plant life. An integrated approach to the design & operation stage is an important consideration that is many times overlooked.
In the basic design phase, the process team ensures design parameters that cover all possible operating scenarios that account for the construction materials used for the chemicals and the appropriate design conditions. The design is developed with suitable automation and control of the process parameters including an adequate Relief System to take care of emergency situations as the last gasp for safety. The active & passive fire protection system is to be planned to control and manage any unwanted event that results in a possible fire or explosion. Quantitative Risk Assessment (QRA) should be performed during the execution phase and its findings should be implemented in the design to ensure that acceptable safety risk is achieved for the entire life of the facility. On top of these controls, additional layers of protection should be built depending on the risk and resultant consequence of a possible undesired event. Many times, QRA is taken as a way to get statutory approvals and not as a necessity to ensure safety in and outside of the premises.
The process of Safety in Design that is planned for the design and engineering phase of the project must include the following steps amongst others:
Review of Key documents (P&IDs, Plot Plan, Area Classification, Model Review) by an experienced team
HAZID and HAZOP Workshops
SIL/ALARP & LOPA as appropriate for the facility
Constructability at various stages of the project
Pre-start up safety review
In summary safety In Design is ensured through the process of proper reviews at an appropriate stage of the project and outcomes are included in the design on a continuous basis. The established norms and practices are to pay attention to and follow for safety and should not be taken as a step for statutory approval of the project to proceed.
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