Refineries, petrochemical plants and other facilities with their own dedicated firewater distribution systems need to know the capacity of their firewater systems to prepare for major incidents, to comply with local, state and federal regulations, or to demonstrate that their facilities have adequate firefighting capacity for insurance purposes.
Commonly, a facility's firefighting department, with assistance from maintenance or operations personnel will perform a few firewater system tests annually, in which a number of hydrants within a part of the site will be opened and flow data recorded. This approach is often less than systematic and may not be sufficient to provide a proper assessment of the system's capability or deficiencies. A complete systematic approach is necessary to provide a proper assessment of the system's strengths and weaknesses. A systematic approach is necessary to consider "what-if" scenarios, which could include, for example, the simulated loss of a key pump or the breakage of critical underground mains.
We have developed firewater system models for the existing systems in refineries, predicted their performance, correlated results with testing, and determined the system demand.
A recent project for a client involved the development of firewater loads for all of the onsite process areas and for a number of the more critical tank storage fire risk areas. The firewater grid model contained over 30 miles of piping, over 1,800 individual pipes, over 1,800 junctions including approximately 800 hydrants plus seven firewater pumps and miscellaneous system wide leaks. To complete the model we reviewed and modeled nearly 100 individual D-size sub-drawings of the firewater grid. Using our approach our team was able to construct and preliminarily validate the model in less than eight weeks. The resulting flow simulations reproduced the site's existing test data to within a few percent of the flows and pressures. Later we assisted the client in evaluating several options to enhance his firewater coverage by running alternative cases for him.