PSI Explained: Design Codes and Standards Employed

In addition to the technical documentation that we have discussed previously (P&IDs, Ventilation System Design, Relief System Design and Design Basis, etc.), Title 8 CCR §5189(d)(3)(A)(6) and Title 29 CFR §1910.119(d)(3)(i)(F) require that a facility have documentation describing the “Design Codes and Standards Employed” readily available for each PSM chemical process. This documentation serves multiple purposes:

• Demonstrates that the process was designed/installed in accordance with recognized practices (often referred to a RAGAGEP – recognized and generally accepted good engineering practice).
• Provides a basis for future audits and inspections. Codes and standards change over time (more on this here), but that does not necessarily force a facility toward upgrades.
• Serves a guideline for approving changes to a chemical process. When Design Codes and Standards Employed is clearly documented, an owner or his representative can objectively verify changes against the code/standard which can help avoid disputes later.

For ammonia refrigeration processes, the International Institute of Ammonia Refrigeration (IIAR), is the leader in developing standards. Anyone wishing to gain expertise in ammonia refrigeration must ensure that they have access to IIAR’s suite of standards in their technical library. Currently, IIAR has published the following standards which cover all aspects of refrigeration system design, installation, commissioning, and decommissioning:

• ANSI/IIAR Standard 1-2012 American National Standard for Definitions and Terminology Used in IIAR Standards
• ANSI/IIAR 2-2014 American National Standard the Safe Design of Closed-Circuit Ammonia Refrigeration Systems
• ANSI/IIAR Standard 3-2012 American National Standard for Ammonia Refrigeration Valves
• ANSI/IIAR Standard 4-2015 Installation of Closed-Circuit Ammonia Refrigeration Systems
• ANSI/IIAR Standard 5-2013 Start-up and Commissioning of Closed-Circuit Ammonia Refrigeration Systems
• ANSI/IIAR Standard 7-2013 Developing Operating Procedures for Closed-Circuit Ammonia Mechanical Refrigerating Systems
• ANSI/IIAR Standard 8-2015 Decommissioning of Closed-Circuit Ammonia Refrigeration Systems

Other organizations also publish design codes and standards that are applicable to ammonia refrigeration. A summary of some of the key documents includes:

• IAPMO – Uniform Mechanical Code
• IAPMO – California Mechanical Code
• ICC – International Mechanical Code
• ASME – Boiler and Pressure Vessel Code Section VIII
• ASME – ASME 31.5 Refrigeration Piping and Heat Transfer Components
• ISEA – ISEA Z358.1 Emergency Eyewash & Shower Equipment
• ASHRAE – ASHRAE 15 Safety Standard for Refrigeration Systems
• NFPA – NFPA 1 Fire Code
• ICC – International Fire Code
• ICC – California Fire Code

It is best practice to require the designer and/or installer to provide a signed statement specifying the codes and standards that were used during design and construction of the process.

Note: For more information on Ammonia Design Codes and Standards, you can review the technical presentation that Peter Thomas, P.E. presented at the 2017 CUPA Conference in San Diego, CA.