Pressure Relief Valves provide protection of life and of the facility (and property within it). When an overpressure condition exists, a pressure relief valve will open and allow overpressure discharge from the pressurized equipment. Relief valves close upon return to normal conditions to prevent excess fluid loss (also protecting the environment in many cases).

Overpressure may exist for a variety of reasons. API Standard 521 applies to pressure relieving and vapour depressurizing systems, and while intended primarily for oil refineries, it also applies to other oil and gas and petrochemical facilities. API 521 provides guidelines for examining the causes of overpressure, determining relief rates, and more. API 521 also provides a list of common overpressure causes that include: 

  • Blocked outlet
  • Inadvertent valve opening
  • Check-valve failure
  • Cooling failure
  • Reflux failure
  • Loss of absorbent, quench, or cold feed
  • Automatic control failure
  • Abnormal heat or vapor input
  • Entrance of highly volatile material
  • Exchanger tube rupture
  • Chemical reaction
  • Thermal expansion
  • Fire
  • Instrument air failure
  • Power failure
  • Other utility failure

Depending on the situation, these occurrences can be independent of one another, or they may occur at the same time. They can be the cause of large or small fluid releases, and care must be taken to ensure that a maximum relief scenario is addressed. It is critical to have an experienced engineering team and design solution to work alongside your facility engineering and maintenance teams for both new and existing facilities. Farris provides this to Western Canadian clients through Tundra Process Solutions, headquartered in Calgary, Alberta. 

Farris doesn’t just provide pressure relief valves. The complete Farris solution includes iPRSM engineering software — a unique program to facilitate the design, audit and documentation of both new and existing pressure relief systems, including the associated disposal (flare) system. When evaluating the pressure relief requirements for a facility, it is important to examine all possible means by which a pressure relief requirement may arise. In addition, all applicable scenarios for a protected system should be evaluated and calculated.

For many systems, one scenario will require the largest orifice area, while another has the highest associated inlet pressure drop, and a third scenario has the highest associated outlet pressure drop. The ability to automatically calculate multiple applicable scenarios is one of the primary advantages of iPRSM over spreadsheet based calculation tools. The common overpressure situations mentioned above are standard scenarios that can be automatically loaded into a Protected System in iPRSM. To learn more about these scenarios, refer to the API 521 guidance document. 

Upon completion of design, analysis and audit, facilities equipped with the Farris line of spring loaded and pilot operated pressure relief valves enjoy the greatest level of protection. Farris has been at the forefront in design and manufacture of spring-loaded and pilot operated pressure relief valves since the 1940s. With more than 70 years of proven performance and Canadian installation expertise, Farris has and continues to provide automatic and positive protection against overpressure situations in thousands of facilities around the world. With the largest installed base of product in Canada, Farris is well versed in operational requirements and provides solutions to industries including hydrocarbon processing, refining, petrochemical, natural gas production and transmission, and more. 

Effective May 15, 2017, Tundra Process Solutions represents Farris and other companies of the Curtiss-Wright Valve group in British Columbia, Alberta and Saskatchewan. “Tundra is proud to represent the Curtiss-Wright product including Farris Engineering solutions. There is simply no one else that offers our industry this much expertise when it comes to overpressure protection,” says Iggy Domagalski, CEO Tundra Process Solutions. “The Farris line is an excellent complement to the complete valve and actuation portfolio of solutions that Tundra has assembled, and we look forward to serving all of our clients with this premier solution for many years to come.”

To learn more about the Farris line of products and solutions, or for more information, please visit tundrasolutions.ca/Farris.