Process Hazard Analysis
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Facility Siting Services
Facility Siting Studies (FSS) can be used to evaluate where to build a new facility, based on risk to nearby neighbors; evaluate where to place process units and occupied structures on new plant sites; to determine where on an existing site to install new processes, based on risks to off-site and on-site populations, and evaluate the risks to occupants of structures on an existing plant site. For any of these purposes, DEKRA Process Safety uses state-of-the-art tools and methods to provide pragmatic solutions for risk minimization.
OSHA’s Process Safety Management Standard requires that Facility Siting be considered during a Process Hazard Analysis (PHA). In the years following the PSM standard, Recognized and Generally Accepted Good Engineering Practices (RAGAGEP) have been developed to meet this requirement such as API RP 752, “Management of Hazards associated with Location of Process Plant Permanent Buildings,” API RP 753, “Management of Hazards Associated with Location of Process Plant Portable Buildings,” and API RP 756, “Management of Hazards Associated with Location of Process Plant Tents.” Facility Siting Studies, due to their complexity, are often conducted separately from a PHA using personnel with specialized knowledge.
Conducting a Facility Siting Study for an Existing Facility
DEKRA Process Safety utilizes a pragmatic approach to minimize the resources required. We typically start with a simple, although, conservative method of evaluation. The results of this often demonstrate that some structures do not need further evaluation. The remaining structures are then subjected to a more rigorous evaluation that produces realistic results compared to the conservative analysis. This often provides sufficient information to develop a Mitigation Plan. Occasionally a small number of scenarios require a detailed analysis of the structure and how it will respond to the calculated overpressure it will endure. While this assessment can require additional time and expense, it’s use is reserved only for those structures that do not meet the acceptability criteria of the previous two methods.
A Facility Siting Study (FSS) must include several critical steps:
1. Identify the buildings that should be included in the study on a case-by-case basis
2. Identify potential incidents that result in fire, explosion, or release of toxic gases and vapors
3. Determine the credible consequences of the events
4. Estimate the impact these incidents could have on occupied buildings
5. Determine what additional steps can be taken to protect personnel
6. Develop and execute a Mitigation Plan.
A similar, stepwise process is utilized for new facilities, plant layouts and plant expansions.
Effective assessments are conducted by a knowledgeable team with access to necessary resources to adequately define the potential impact of accident scenarios and how personnel might be impacted. The assessment team should include, or be led by, someone trained and experienced with the evaluation techniques. These might include:
• Evaluating spacing distance recommendations from relevant sources of RAGAGEP
• Modeling of explosion overpressures, heat radiation from fires, and dispersion modeling of toxic releases based on the specifics of your facility
• Evaluation of the risks of evacuation vs. sheltering in place, based upon infiltration of the toxic vapor or gas into the structure
• Calculating the credible likelihood of an event occurring
The assessment should be documented and kept evergreen as changes are made to the facility. Revisiting the study may be required as part of Management of Change evaluations. Events that may affect the Study include raw material changes, inventory changes, introduction of new products, new construction and relocation of personnel. DEKRA can evaluate which sections of your Facility Siting Study would be impacted by a change, and re-evaluate only those sections that might be impacted.
