Pressure Relieving System Design

The Flare is a major part of the pressure relieving system for hydrocarbon processing plants. For most plants it is the last line of defence against potential hazards. Flare design should include thermal radiation limits, explosion hazards, liquid carryover, noise, temperature limits, and ground level concentrations of combustion products.

In Hydrocarbon Service there has been several flare line ruptures, therefore it is something each Processing Plant should review, particularly at every revamp or expansion.

We believe that Every Organization should have specific training and knowledge in these Safety Areas;

1. Hazard Identification

2. Pressure Relief Valve and Flaring System Design and Operation

3. Guide Lines for Safe Commissioning of Process Units

Pressure Relieving and Flare Design

It is very important that when this system is designed or modified that the design team understand the fundamentals of pressure relieving system design and the critically of this system.

This system includes;

  1. Pressure Relief Valves
  2. Flare Header
  3. Flare Knock Out Pot
  4. Flare Liquid Pumps
  5. Flare Stack
  6. Flare Seal
  7. Flare Tip

A typical Pressure Relieving System Design or Review includes;

1. Develop Pressure Relief Valves design for multiple cases

  1. Gather Relevant data - PSV Data Sheets, P&IDs, Piping Isometrics
  2. Develop Creditable Relief Scenarios, Power Failure, Cooling Water Failure, ect
  3. Calculate Correct Relief Valve Size after steps 2 and 3 are completed to determine the true back pressure

2. Complete Relieving System Heat and Material Balances with thermodynamic packages in Process Design Simulator such as PRO II, which includes condensation and two phase flow affects for the correct back pressure calculations

  1. Physical properties generated for each stream

3. Development of Flare Header hydraulics and sizing utilizing the Heat and Material Balance Corrected Flows

  1. Developed the True Back Pressure of each relief valve<

4. Development of Flare Knock Out Pot sizing and velocities

5. From the Heat and Material Balance develop KO Pump sizing

6. Review Flare Seal Design from Vendor

7. Review Flare Tip Design from Vendor

8. Develop Flare Radiation Heat Circles and Required Stack Heights


Additional Items that can be developed or reviewed include;

1. Reduced Flaring Systems by the use of High Integrity Protection Systems (HIPS)

2. Evaluation of maximum flaring cases with existing flare system

3. Revamp strategies and modifications for existing flare systems

4. Generate all required documentation or OSHA or internal company requirements

KLM's Team of highly experienced engineers can assist your team in developing the basic design or detailed design of a Pressure Relieving System.

Pressure Reliving System White Papers

Flare Design Manual (Engineering Design Guidelines)

Pressure Relief Valve Design Manual (Engineering Design Guidelines)

Vessel Sizing Design Manual (Engineering Design Guidelines)

Flare Header Design Manual (Engineering Design Guidelines)

Flare Case Study #1

Flare Case Study #2