Quantitative Risk Assessment for a Chemical Facility Case Study


The Challenge

A client needed to update a previous Quantitative Risk Assessment (QRA) study of their plant to ensure the QRA reflected the most recent changes to equipment and buildings. OSHA 29 CFR 1910.119 Process Safety Management (PSM) requires, under the Process Hazard Analysis (PHA) element, that employers conduct a facility siting study to verify that the location and occupancy of buildings, control rooms and trailers have been properly evaluated.

Our Approach

ioMosaic completed an updated QRA of their plant to determine the peak overpressure, positive phase duration and impulse at the proposed new location of their ammonia building maintenance as a function of the frequency of occurrence. The analysis and documentation were prepared using Process Safety Office® SuperChems™.

The purpose of the Quantitative Risk Assessment study is to identify any potential hazards and risks associated with the project and to provide guidance for siting in order to minimize risks. It involves estimating the frequency of potentially hazardous events and calculating the consequences of such incidents. The results are combined with information on the expected exposure of persons to the events being studied, to establish a risk of injury or death.

The QRA process is divided into five main elements as follows:

  1. Identification and development of a representative set of hazard scenarios utilizing commonly accepted methodologies, including failure mode and effects analysis.
  2. Evaluation of the likelihood of occurrence of these identified hazardous events, based on a specified number of release sizes (utilizing among other things, the fault tree analysis methodology).
  3. Evaluation of the possible consequences from the identified hazardous events utilizing our state-of-the-art hazard modeling software, SuperChems™.
  4. Evaluation of risk, the combination of frequency, and consequences.
  5. Consideration of the significance of the resultant risk levels and, if appropriate, mitigation measures and recommendations to meet relevant risk criteria (risk tolerability criteria developed during the previous QRA will be utilized).

The Benefits

ioMosaic combined the consequence and likelihood results to give an estimation of the individual risk visually via iso-risk contours displayed on plot plans. Additionally, the study provided a list of predicted values in terms of peak overpressure, positive phase duration, and impulse to all buildings within the facility. The resulting project deliverables included a final report draft report of the results and any recommendations detailing the safety risks.

Learn More

Our mission is to help you protect your people, your plant, your stakeholder value and our planet. To learn more about how we can help you manage risk, call us at 1.844.ioMosaic.