What you'll learn:
- Understand the role of pressure relief systems in protecting equipment and personnel.
- Identify and compare various types of PRVs and rupture discs, including their applications and limitations.
- Evaluate different overpressure scenarios and select appropriate relief strategies.
- Size and Select Pressure Relief Valves in Accordance with API Standard and ASME Code for gas, steam and liquid services
- Analyze the effects of back pressure, blowdown, and inlet pressure losses on valve performance.
- Understand the documentation needed for relief system design package
This course is also available as part of my engineering training library on chemengpro, where I share tools, templates, and bonus materials for engineers.
Chapter 1: Introduction to Pressure Relief Devices
Understand the purpose of pressure relief valves (PRVs) in industrial systems
Compare pressure relief valves vs rupture discs — pros, cons, and typical use cases
Learn the function of relief devices in series and when dual protection is required
Chapter 2: Types of Relief Devices and How They Operate
Explore the types of pressure relief valves: spring-loaded, weight-loaded, balanced, and pilot-operated
Understand the impact of back pressure on PRV performance
Compare conventional vs balanced pressure relief valves
Learn key pressure safety definitions:
Set pressure, design pressure, maximum allowable working pressure (MAWP), overpressure, accumulation, blowdown, closing pressure, relieving conditions
Identify the mechanical components of a PRV
Understand open vs closed bonnet designs
Learn the differences between gas relief valves and liquid relief valves
Introduction to:
Balanced PRVs
Pilot-operated PRVs
Rupture disc devices
Rupture pin technology
Chapter 3: Pressure Relief Standards and Codes
Understand the difference between codes vs standards
Introduction to ASME Boiler and Pressure Vessel Code (BPVC)
Overview of ASME certification requirements for PRVs
Introduction to API 520, 521, and 526 standards related to relief valve sizing and design
Chapter 4: Overpressure Protection Scenarios and Design Philosophy
Identify common overpressure scenarios in process industries
Differentiate between reasonable and unreasonable scenarios
Understand the concept of double jeopardy in risk assessment
Analyze causes of overpressure with examples:
Operator error
Instrumentation failure
Blocked or closed valves
Check valve failure
Utility failure (e.g., cooling water, steam, power)
Plugged filters or vents
Heat exchanger tube rupture
Chemical reactions
Hydraulic expansion
Fire exposure:
Fire in liquid-filled vessels scenario
Fire in gas-filled vessels scenario
Learn best practices for fire overpressure protection
Understand the limits of PRVs — when additional safeguards are needed
Introduction to underpressure scenarios and vacuum relief
Learn about the required documentation for a complete relief system design package
Chapter 5: Relief Valve Sizing Calculations and API/ASME Methodology
Follow API/ASME-compliant pressure relief valve sizing guidelines
Understand key sizing considerations:
Orifice area selection
Effective area vs actual area
Rated vs effective discharge coefficient (Kd)
Review PRV inlet pressure loss and outlet back pressure limitations
Understand Cold Differential Test Pressure (CDTP)
Determine relieving pressure for:
Single-failure contingencies
Multiple (double) contingencies
Fire case scenarios
Perform PRV Sizing Calculations for:
Gas service – Critical flow
Gas service – Subcritical flow
Steam relief valves
Liquid relief valves (High Viscosity and Low Viscosity)
Rupture Disc Sizing and Selection
Learn rupture disc sizing methodology under API/ASME
Define and apply:
Burst pressure
Manufacturing range
Burst tolerance
Operating ratio
Understand how to select, specify, and size rupture discs for industrial applications
