Pressure Relief Valve Sizing & Selection (ASME/API)

Pressure Relief Valve Sizing & Selection (ASME/API) free download

Learn to size and select PRVs using ASME Section VIII & API 520/521. Includes relief scenarios, equations, and examples.

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