iPRSM is a unique solution for the design, audit and documentation of both new and existing pressure relief systems, including the associated disposal (flare) system.

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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. 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 following are the standard scenarios that can be automatically loaded into a Protected System in iPRSM. For further information on overpressure scenarios, please consult the API 521 guidance document.

  • 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
  • Other

Users are not limited to the above scenarios and may define alternative scenarios for their facilities within iPRSM.

Want to learn more?

For further information, a demonstration or evaluation session and training classes, please contact us at:

T: +1.281.724.2222 | E: FES@curtisswright.com

Document repositoryArrow
Beyond performing complex calculations, iPRSM also acts as a historian and file server for all of your company and facility’s important documents. iPRSM is not designed to replace asset management software, rather it complements your existing packages. iPRSM utilizes an easy to understand hierarchy. At the corporate level you might store items like engineering standards and directives or industry codes. At the unit level, store your process unit’s P&ID’s and heat and material balances. And at the protected system level iPRSM will house all of the information upon which your relief calculations are based. You can store required equipment parameters like discharge coefficients, flow capacity, links to vendor brochures, etc and attach them directly to the corresponding equipment. Uploading field data sheets, process data sheets, spreadsheets, pictures, etc is simple. Now you can have all of the information for these complex calculations housed in one convenient location.
Evaluate all overpressure scenariosArrow
iPRSM will automatically consider any scenario selected by the calculating engineer. iPRSM can automatically load all standard scenarios per API 521, or the calculating engineer can select scenarios as deemed appropriate. Custom scenarios can also be considered. Scenarios not considered can be appropriately documented to meet PSM requirements.
Integrated thermodynamicsArrow
iPRSM uses an integrated thermodynamics calculation engine to determine flow rates, phase information, temperatures, pressures, etc, for your process conditions and determines the conditions your equipment may experience during a relieving scenario. iPRSM has many different equations of state to select from depending on the type of compounds you are working with. iPRSM can easily handle normally time consuming calculations like two-phase flow using direct integration. iPRSM’s physical properties library contains more than 2,000 pure components and allows the flexibility to add custom compounds.
Project work flow toolArrow
iPRSM will help your multi-discipline team move efficiently through each phase of a relief system design or audit project. iPRSM has task queues available to assign work to different team members. iPRSM enhances the effectiveness of a project team by making work handoffs and collaboration seamless.
Relief device sizing calculationsArrow

iPRSM calculates the required orifice area and inlet and outlet pressure drops of a relief device. All of the calculations are performed per the latest codes and standards.

iPRSM also uses all of the latest and most accurate calculation methods to appropriately size relief devices. Among the current calculation methods for two phase flow are the DIERS Omega method and Direct Integration.

What are the alternatives to iPRSM?Arrow

The traditional method of performing relief system calculations has involved complex spreadsheets combined with process simulators to obtain physical properties and thermodynamic data. A major deficiency with a spreadsheet approach is that it is difficult, if not impossible, to automatically evaluate the effects of process or equipment changes on multiple protected systems. This approach will likely provide you with an accurate snapshot of the process as calculated. However, with ongoing changes to your process and equipment, deficiencies in your relief systems are likely to slip by undetected. The most dangerous issue at your facility is the one you don’t know about.

Other PC based software packages are available. These packages lack the connected nature that iPRSM offers as a web based tool. In iPRSM, users collaborate in a single, common database as opposed to working from isolated computers. This approach ensures that all users always work with the most current data.

Other packages also require your entire team to have a common computing platform which becomes an issue when operating systems or other related software are upgraded. iPRSM simply needs a device with a web browser and can even be accessed via tablet or smart phone. With iPRSM the calculations take place on secured servers. The result is the bare minimum of computing power requirements.

Why audit a Relief System with iPRSM?Arrow

As the equipment and process at a facility undergoes changes over time, it is important to verify that installed relief devices remain adequate for their protection role. iPRSM is built with protected systems as the building blocks. Protected systems are comprised of equipment that is protected, protecting, ancillary, or an overpressure source. It is common for equipment to be linked to more than one protected system and to play a different role to each system. For example, a pressure relief valve may be protecting a piece of equipment in one system, but also be ancillary to an upstream protected system. iPRSM is the only tool available that identifies the multiple roles played by a single piece of equipment. The result is that iPRSM will illuminate issues in your relief system that may have otherwise gone undetected.

If you need help auditing your relief system, Farris Engineering Services routinely audits our customers’ relief systems to ensure they will protect their assets.

Why design a Relief System with iPRSM?Arrow
Relief Systems are put in place to protect equipment in the process facilities from pressures the equipment was not designed to tolerate. When relief systems are called upon, they protect the equipment to which they are connected and also the people and environment in the immediate vicinity. Relief systems have an extremely important role and their appropriate design and implementation is a difficult undertaking. iPRSM was built to handle all aspects of relief system design, from calculations to PSM documentation to project management. And because iPRSM is both web based and an efficient project management tool, it connects your project team like you may have never thought possible. If you are ready to design a relief system for your facility, iPRSM will be an invaluable part of the process. If you need assistance designing your relief system, Farris Engineering Services has the experience and expertise to help you protect your most important assets.
Why Use iPRSM?Arrow
iPRSM is the most comprehensive tool available for the study of pressure relief systems and the associated Process Safety Management (PSM) compliance. Once your website is built in iPRSM, it becomes an evergreen document and integral part of your Management of Change (MOC) process. iPRSM is a long term answer to the challenge of ongoing PSM compliance. Using iPRSM will eliminate the need to revisit the efficacy of your relief systems year after year. iPRSM will save you time and money, but more importantly, it will help you ensure that your people, equipment, the community, and environment are protected.

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