1982 Uniform Mechanical Code and “Adjoining Ground Level”

July 7th, 2015 | , ,

Anyone who operates an “older” ammonia refrigeration system in California should be familiar with the requirements of the 1982 Uniform Mechanical Code. Cal/OSHA regulation Title 8 CCR §3248(a) requires the following:

“Mechanical refrigeration systems placed in service before March 13, 1999, shall be designed, installed, tested, and maintained in accordance with Chapters 4, 15, and 16 of the 1982 Uniform Mechanical Code (UMC).”

1982 UMC

The precedent set by this law is that a model code which is updated on a 3-year cycle has been cemented into California law so that OSHA has authority to cite a facility built in 1998 for not adhering to the requirements of the 1982 UMC even though the UMC was revised five (5) times between 1982 and 1998.

With that as a backdrop, I recently consulted at a facility which had been cited for not complying with Title 8 CCR §3248(a). Specifically, the citation was in regards to the location of the atmospheric relief vent discharge termination pipe relative to the machinery room roof and adjacent roof.

1982 UMC §1517 reads:

1517
The client’s complaint was that the relief valve discharge termination point was more than 15 feet above the machinery room roof, but only 2 feet above the roof of the adjacent building. The client felt he was “in compliance” since the termination point was “not less than 15 feet above the adjoining ground level“.
The following was my response to the situation:

John, I understand your perspective relative to a plain reading of 1982 UMC. Before addressing your concern, let me first make clear what the current codes require relative to this situation:

ANSI/IIAR 2-2008 Addendum B §11.3.6.4 

The discharge from pressure relief devices to the atmosphere shall be not less than 15 feet [4.8 m] above the adjacent grade or roof level or as specified by the jurisdictional authority and shall be arranged to avoid spraying of refrigerant on persons in the vicinity.

As you can see the semantic issue is “adjoining ground level” (1982 UMC) vs. “adjacent grade or roof level” (ANSI/IIAR 2-2008 Addendum B). This is something that has been hashed out quite a bit in the refrigeration industry. Please review the attached Interpretation IC 15-2001-2 of ANSI/ASHRAE 15-2001 which uses the exact same language at 1982 UMC. As a result of this interpretation and others, the language “adjoining ground level” has been changed in codes to “adjacent grade or roof level” to be more clear on intent. However, precedent exists to treat a roof where employees may work as an “adjoining ground level“. With that in mind, the OSHA citation is valid relative to industry consensus on the meaning of “adjoining ground level“.

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