Emergency Relief System Design

Reducing costs and increasing accuracy in the design or revalidation of relief systems.

Effective Emergency Relief System (ERS) design helps companies meet risk-management goals, compliance requirements, and sound business practices. ioMosaic provides a total ERS solution with our comprehensive ERS design services, from reactivity testing for design basis determination to calculations for Z-axis deflection from dynamic loads.

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How We Can Help You

Our team has decades of experience performing PRFS analysis and design.

Our risk-based approach helps mitigate near-unventable scenarios to a tolerable level of risk.

Better evaluate hazards in your facility with an accurate process simulation.

Delivering properly designed pressure relief systems that save both money and time.

Have a Question on Emergency Relief System Design?

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Featured Resources


Understanding MAWP and High-Pressure Vessel Design

Gain an Understanding of Maximum Allowable Working Pressure (MAWP)

Read this white paper to understand how and who determines the maximum allowable working pressure (MAWP), the relationship between MAWP and Design Pressure, and finally how high-pressure vessel is designed.

Read the White Paper

Calculate Phase and Chemical Equilibria Using Process Safety Office® SuperChems™

Direct minimization of the Gibbs free energy can be used to calculate phase equilibria, chemical equilibria, and/or simultaneous physical and chemical equilibria. This method may be preferred for systems where multiple liquid phases can coexist and/or where retrograde phase behavior is possible during depressuring or pressure relief. 

Some of the advantages of direct minimization of the Gibbs free energy include:

  • The atom matrix can be constrained to ensure that inert liquids and/or inert gases are only present in their respective phases. For example, this can be useful for systems containing hydrogen and heavy polymers.
  • The atom matrix can be constrained to ensure partial or user defined conversion of one or more chemical species.
  • Multiple liquid, vapor, and solid phases can be handled simultaneously with simplicity.
  • Phase splitting can be determined a priori.

Some of the disadvantages include:

  • The Gibbs free energy minimum can be very flat and requires high precision estimates.
  • The Formation energies of all chemical species have to be thermodynamically consistent and calculated at the system temperature using reference elements.
  • Reasonable initial guesses for phase splitting are required. Normally, the most non-ideal liquid component in the mixture will likely form the dominant component in one liquid phase while the second most non-ideal liquid component will likely form the dominant component is the second liquid phase.

Minimization Algorithm

The computation of the equilibrium state of a system is one of constrained optimization. The minimization of the Gibbs free energy is subject to mass, element balance constraints, and where applicable, user defined constraints. Recent advances in the field of nonlinear optimization have greatly simplified the solution of this problem. Process Safety Office® SuperChems™ component uses the Wilson-Han-Powell successive quadratic programming (SQP) algorithm to directly minimize the Gibbs free energy for nonideal multiphase systems. Advantages of this algorithm include its low number of function and gradient evaluations and its ability to handle simple bounds on variables, such as non-negativity constraints which eliminates the need to transform variables in order to avoid singularities.

Our Team

Georges A. Melhem, Ph.D., FAIChE

President & CEO The founder of ioMosaic and internationally renowned expert in the areas of pressure relief and flare systems design, chemical reaction systems, process safety and risk analysis. Read more...

Neil Prophet

Senior Vice President and Partner Pressure relief and flare systems design project management and engineering expertise for chemical, pharmaceutical and petrochemical companies. Read more...

Daniel Nguyen, PE & PMP

Senior Vice President and Partner Responsible for a team of software engineers in the development of ioMosaic’s PSO software and manages pressure relief and flare systems evaluation and design projects. Read more...

John Barker, Ph.D.

Director The Director of our U.K. office and an expert in risk management for the international oil and gas and transportation industries. Read more...

Marcel Amorós-Martí

Director, California Office Lead His expertise includes pressure relief and flare systems design for large chemical and petrochemical companies around the globe and in the United States. Read more...

Charles Lea, P.E.

Director, Minneapolis Office Lead He directs a number of large technical projects across multiple offices and is also responsible for all project management in our Minneapolis office. Read more...

Ying Zhang, P.E., PMP

Senior Safety and Risk Management Consultant Chemical engineer focused on pressure relief and flare system design and analysis for large chemical and petrochemical companies in the U.S. Read more...

Matthew LeVere, P.E.

Senior Safety and Risk Management Consultant Experienced in PRFS design and analysis for clients in the petrochemical, chemical, and pharmaceutical industries. Read more...

Neal Dahlheimer, CPPM

Senior Safety and Risk Management Consultant Technical lead on PRFS projects for chemical, petrochemical and oil facilities as well as QA/QC reviews and training on advanced techniques for complex systems. Read more...

Featured Videos


PSE Emergency Relief System Design Workflow

Process Safety Enterprise Emergency Relief System Design Workflow performs efficient tracking of process safety related data and analysis. The customized workflow allows for a specific operating unit or the entire facility to be studied and evaluated to maintain compliance and ensures your facility remains protected.

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Featured Case Studies

Fire Exposure and Relief Protection for Vessels Containing Reactive Chemicals

The client was storing reactive materials in vessels that could be subject to fire exposure. They wanted to be sure that the relief protection on the vessels was correctly sized, or if not, what changes were necessary for an effective relief system.

View Case Study
A refinery approached ioMosaic for the purposes of ensuring that pressure relief capacity was adequate for the loss of liquid seal scenario in a high-pressure separator (2,000 psig). They were also concerned about the pressure waves that would occur in the high-pressure separator’s outlet lines on rapid closing of the isolation valves and sought our expertise.
A large oil refinery with a very complex flare network had become so complex that the tools the refinery was using to evaluate the flows through the flare network could not adequately model the system. Management no longer had confidence that their model results reflected the actual network performance and therefore, could not be sure the system would perform properly in the event of a global relief scenario at the facility.
A multinational energy company wanted to complete an evaluation of a PRV system in order to comply with the PSM standard OSHA 29 CFR 1910.119 which requires that employers compile information pertaining to the equipment in the process, including relief system design and design basis. 

Featured Services

Pressure Relief and Flare System Design

Our risk-based approach helps mitigate near-unventable scenarios to a tolerable level of risk and develop economical designs for more credible events. Read more...

Relief Header and Flare Analysis Systems

Delivering properly designed pressure relief systems for refineries and chemical plants that save both money and time. Read more...

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