Fire depressurisation analysis
and relief design

This seminar describes two important applications of dynamic analysis in fire overpressure protection. The first part of the seminar introduces an analytical methodology to assess system survivability under fire attack, and so inform blowdown system design in upstream processes. Updated industry standards, including the 6th edition of API 521, now recognise the need to consider vessel stress during blowdown and, critically, that guidance issued prior to 2014 may not be an appropriate basis for vessel survivability. This explains why vessels are at risk when exposed to fire, the potential for loss of containment and the possible escalation to a major hazard. The impact on process design is evaluated through a series of relevant project case studies in offshore platforms and gas processing facilities. These case studies demonstrate how a fully integrated dynamic model optimising transient blowdown loads with available flare capacity improves accuracy, reduces uncertainty, and provides solutions to complex situations where application of Passive Fire Protection is not practical or flare capacity is limiting.

In the second part of this seminar we discuss relief valves. These are considered more suitable for protection of vapour/liquid pressure systems in LNG and Refining/ Petrochemical plants. The fire relief load is often not governing for relief valve or flare sizing, however many manhours are expended on these calculations. This session reviews the basis for fire sizing and the common pitfalls with Industry sizing methods and introduces the application of dynamics to solve the fire heat input to the fluid and to provide the most accurate sizing of valves in a single tool.

The over-conservatism inherent with standard industry methods is significantly reduced. Users will also appreciate the benefit of reduced effort and uncertainty in preparing fire calculations with improved accuracy in valve sizing.

This session features a live demonstration of the tool and its features. Two case examples are presented from a recent relief valve verification study, where the tool was used to establish that valves were acceptable as designed after standard methods showed them to be undersized.

Seminar agenda

8:30 Registration, refreshments
9:00 Introduction
  • PSE Oil & Gas and gFLARE
  • Fire depressurisation analysis and relief design
9:10 Session 1 - Fire analysis and overpressure protection requirements
  • Basis for provision of pressure relief devices and depressuring systems
  • Pool and jet fires
  • API 521 6th edition requirements for depressuring
9:30 Session 2 - Guidelines and workflows
  • Guidelines for API 521 empirical and analytical methods
  • The analytical method for fire analysis
    • Vessel wall temperature
    • Stress calculations and rupture prediction
    • Validation: BAM fire test and analysis
  • Fire analysis workflows: flare limitations, rupture
    • Aims and key considerations RO sizing, flare limits, rupture, Passive Fire Protection
    • Conventional workflows, tools and limitations
    • Handling of uncertainty
Session 3 - Case studies - Enhancements to workflow and calculations
  • Case study 1: Reducing Passive Fire Protection (PFP) requirement on an offshore facility
  • Case study 2: Slug catcher staged blowdown sizing
11:00 Refreshment break
11:20 Session 4 - Fire relief sizing and application of dynamics
  • Use of dynamic simulation in fire relief design
  • Demonstration of new gRELIEF tool
  • Case study 1: Fire liquid vaporisation - LPG storage vessel
  • Case study 2: Fire gas expansion - Fuel gas heater

Seminar attendees are also granted complimentary access to the afternoon Oil & Gas session of the APM Forum.

12:30 Lunch
14:00 APM Forum - Oil & Gas and Refining Session

Please see the Oil & Gas open day agenda for complete information on the afternoon session. Topics will include:

  • Challenges for Oil & Gas operators: an industry perspective
  • New solutions for oil & gas - a showcase
    • New developments for oilfield production optimisation
    • Advanced steady-state and dynamic modelling and optimisation of Natural Gas Liquid Recovery units
    • Model-based real-time monitoring of a subsea gas pipeline network
  • Round table discussion: Production system modelling, integrated asset modelling, multiphase pipeline systems and related topics
  • CO2 capture in natural gas production using adsorption processes
  • New tools for optimising refinery operations
17:30 End


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