# 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.

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.

# 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.

# Analysis of PRV Stability In Relief Systems Part IV

On the estimation of speed of sound and thermodynamic properties for fluid flow and PRV stability. An independent and accurate estimation of the speed of sound can provide an important quality check for a multitude of single and multi-phase flow applications. More recently, proposed screening methods for the calculation of PRV stability require an accurate estimate of the speed of sound for the fluid/piping system. This paper outlines proper methods for the calculation of thermodynamic properties and speed of sound for single and multi-phase systems. Comparisons with actual measurements indicate that credible values can be obtained for single and multi-phase systems.

The speed of sound, c, characterizes the propagation of an infinitesimal pressure wave in a fluid that is unconfined. The speed of sound can be calculated for a single or two-phase unconfined fluid by evaluating the change in mixture density (with or without slip) with respect to pressure. Where the effects of conduction heat transfer are negligible, the equilibrium speed of sound is given by the derivative of pressure with respect to density at isentropic (adiabatic) conditions: where s is the isentropic compressibility,  is the fluid mass density, T is the isothermal compressibility, Cp is the real fluid heat capacity at constant pressure, Cv is the real fluid heat capacity at constant volume, and P is the system pressure. Where the effects of conduction heat transfer are dominant, the frozen speed of sound is given by the derivative of pressure with respect to density at isothermal conditions: The equilibrium (isentropic) speed of sound cs is always larger than the frozen (isothermal) speed of sound cT: For most liquids (see later section on heat capacity ratio) and two phase flow, the heat capacity ratio is typically close to 1 and the change of pressure with respect to density at constant temperature is close to that at constant entropy at low to moderate pressures. As a result, the speed of sound for most liquids can be approximated by:

## 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...

## Katherine Anderson, CCPSC

Principal Consultant Experienced project leader in hazard identification, evaluation, functional safety, process safety and risk management. 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...

## Gemma Dunjó, Ph.D.

Director, PSM Practice Lead Expertise in environmental auditing, HSE regulatory compliance, environmental modelling, environmental impact reports (EIR) and safety and risk management. Read more...

# PSE Emergency Relief System Design Workflow

Process Safety Enterprise<sup>&reg;</sup> 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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# 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.

## 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...

• May 21, 2020

• Apr 15, 2020

• Mar 12, 2020