Facility Siting Study for U.S. Chemical Facility
Read how ABS Group helped a major chemical company quantify and manage their explosion, fire and toxic risk exposure.
Identify explosion, fire and toxic hazards
Produce CFD models to gain deeper understanding of the potential consequence of explosion, fire and toxic risk
Provide customized, cost-effective solutions
A U.S. chemical facility covered under the Occupational Safety and Health Administration's (OSHA's) Process Safety Management (PSM) regulations, required a facility siting study to better understand the risk to personnel. The study concentrated on an occupied portion of one of the process buildings and two additional buildings located in proximity to the indoor process. At the client’s request, ABS Group provided a 2-stage proposal with both a base and optional scope of work.
Facility Siting is a requirement for all oil, gas and chemical facilities following the Environmental Protection Agency (EPA) and OSHA PSM regulations. It falls within the Process Hazard Analysis (PHA) section of the PSM regulation.
- High-level understanding of the risk to personnel in an occupied building.
- Comply with OSHA PSM and EPA RMP regulations.
The Base Scope
The base scope of work involved a consequence-based study, using both gaussian dispersion models (utilizing the Process Hazard Analysis Software Tool - PHAST) and source energy vs distance relationships for blast load prediction using our proprietary FACET3D software. Per the regulations, we would analyze explosion, fire and toxic hazards and evaluate for evacuation as an emergency response to a fire or toxic incident. The client would receive a detailed report of their overall risk, along with recommendations for mitigation. This base scope of work was the least expensive of the two, commonly referred to as a “screening study,” which uses more conservative analysis methods and ultimately produces a higher severity answer.
The Optional Scope
For the optional scope of work, we proposed to model releases inside the building using Computational Fluid Dynamics (CFD). CFD is a more rigorous numerical approach, better suited for analyzing hazards from indoor releases than traditional analytical explosion, fire and toxic hazard assessment methods developed for outdoor releases. The results of this style of study are more focused and provide less severe consequences, but the price is higher and some projects do not require this detailed level of study.
The Chosen Solution
The client opted to move forward with the base scope of work and accepted the risk of higher consequence outcomes. However, after we performed the base scope of work, the results were discussed with the client and they were informed of several issues they needed to address. The conservative approach had left some high-risk scenarios that would require major capital expenditures to strengthen three occupied buildings to improve their blast resistance to more adequately protect personnel. At this stage, we reminded the client of the optional scope of work that was initially foregone, informing them that it was still our belief that additional analysis to more accurately model the propagation of the blast wave and the resulting structural response of each building was still the most cost-effective path forward. The client then elected to proceed with the optional scope of work.
The CFD Study
We sent a CAD technician to the site to laser scan the process building where the explosion could originate. The CAD technician then used these scans to produce a 3D model of the buildings and process equipment that could influence the dispersion of flammable vapors and the severity of the explosion. Our team then used the FLame ACceleration Simulator (FLACS), which utilizes CFD to model the vapor cloud explosions.
In contrast to the base scope of work, which resulted in the need to structurally retrofit three buildings, the optional scope of work, utilizing CFD to more accurately model the explosions, resulted in the structural failure of only one building. The modeling also showed reduced blast loading to the single remaining building versus the initial scope, which translates to a less robust level of structural strengthening needed. This opened up the door for a wider range of protective design concepts to be explored and utilized to provide the required protection.
In this case, the value ABS Group provided to the client, was in the level of support we were able to provide. Our unique knowledge and experience with both high-fidelity CFD explosion modeling and assessing the structural response of buildings subjected to blast loading was very valuable to this client. We worked in tandem with the client to address their needs at each stage of the project, providing information for them to make the most cost-effective decision at each stage.
In this case, and indeed in many cases we work on, clients often resort to the lowest cost solution first, but we aim to offer our clients a range of options to suit them and their needs. We use our experience and expertise to support them through each facility siting study and revalidation, offering a range of solutions at a range of costs. We regularly meet with clients to support them in evaluating their solutions and can support them through each recommendation we make.
For this client, we have since provided a follow-up proposal to assist them with the support they need for their mitigation strategy. We have proposed three options to them with varying degrees of complexity and cost and have met with them on several occasions providing them with cost-benefit analysis.