RAGAGEP: Codes, Standards, and Good Engineering Practices (Part 6)

March 20th, 2018 | , ,

Peter Thomas, P.E. recently wrote a technical paper and presented at the 2017 RETA National Conference on the topic of RAGAGEP: Codes, Standards, and Good Engineering Practices. This is the sixth in a series of blogs which include excerpts from his technical paper. The previous blogs are available in the following links: Part 1, Part 2, Part 3, Part 4, and Part 5.


The term grandfather is often used in reference to requirements contained within new codes and standards. The typical situation that occurs is that a facility or system is built according to the “codes” in place at the time of design and construction. Over the course of time, new codes and standards are released which contain new requirements which were not implemented during the initial design and construction. Is the facility exempt from the new requirements because they are “grandfathered” to the earlier codes? The answer is likely “Yes”, but the scenario below will assist in providing further explanation:


  • Cold Storage Facility with an ammonia refrigeration system was built in 1969 in accordance with the 1967 Uniform Mechanical Code (UMC).
  • In 1998, modifications were made to the machinery room
    • One (1) new compressor installed
    • AHJ required ventilation and detection to be upgraded
    • All changes were performed in accordance with 1997 UMC
  • In 2014, the facility hired a contractor to construct a new cold storage room
    • No machinery room modifications were required
    • New room complied with 2012 International Mechanical Code (IMC) and ANSI/IIAR 2-2008 Addendum B
    • The facility elected to upgrade the ammonia detection system for entire facility to comply with 2012 IMC

In this example, all four RAGAGEPs would be applicable at the facility, but their applicability would vary based on when the equipment was installed at the facility. 1967 UMC would continue to be the RAGAGEP for the originally installed and unmodified parts of the system. 1997 UMC would apply as RAGAGEP for the machinery room modifications that took place in 1998. 2012 IMC and ANSI/IIAR 2-2008 Addendum B would be RAGAGEP for the ammonia detection system and new cold storage room.

It is important to note that some RAGAGEPs are applicable to all systems as soon as they are published. For example, ANSI/IIAR 5-2013 Start-up and Commissioning of Closed-Circuit Ammonia Refrigeration Systems addresses the “basic minimum requirements for the safe start-up and commissioning of completed closed-circuit mechanical refrigerating systems utilizing ammonia as the refrigerant and to additions and modifications made to such systems.” Therefore, this standard would apply to the start-up and commissioning activities for all newly completed or modified ammonia refrigeration systems, regardless of when the system was built.

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