This 2020 LOI rescinds the letter issued on July 25, 2019, to Ms. Hill, by removing the parenthetical in the second paragraph of the background section. This is an interpretation regarding a possible conflict on the minimum separation distance between aboveground liquefied petroleum gas (LPG) containers and buildings in OSHA’s 29 CFR § 1910.110 – Storage and Handling of Liquefied Petroleum Gas Standard, and National Fire Protection Association (NFPA) 58 – Liquefied Petroleum Gas Code (2017 Edition). This letter constitutes OSHA’s interpretation of the requirements discussed in the letter and may not be applicable to other questions not delineated within your original correspondence.
NFPA 58 (2017), Sections 6.28.2 and 6.28.3 allow for the minimum separation distance between aboveground LPG containers (used for stationary engines) and buildings to be one-half the distance required by OSHA’s Standard, 29 CFR § 1910.110(b)(6)(ii).
Under 29 CFR § 1910.110(b)(6)(ii), each individual LPG container must be located within a specific distance from the nearest important building or group of buildings in accordance with Table H-23.
NFPA 58 (2017) Section 6.28.2 requires containers for stationary engines to meet the separation distance requirements in Section 6.4.
NFPA 58 (2017) Section 6.28.3 includes a provision for LPG containers for stationary engines that have a fill valve with an integral manual shutoff valve to have a minimum separation distance one-half of the distance specified in Section 6.4. Section 6.4 references Table 6.4.1.1 that lists the separation distances between containers, important buildings, and adjoining property lines.
Question: Will OSHA accept NFPA 58 (2017), Sections 6.28.2 and 6.28.3, as a reduction in LPG container separation distance as being in compliance with 29 CFR § 1910.110(b)(6)(ii)?
Response: No, OSHA will not accept the reduction in LPG container separation distance specified in NFPA 58 (2017), Sections 6.28.2, and 6.28.3.
OSHA agrees that adding an engineering control (e.g., fill valve with an integral manual shutoff) may provide better isolation and may prevent flammable gas from escaping when the hose end valve is disconnected. This safeguard, however, relies on human intervention (e.g., operator closing the valve) and does not eliminate other LPG release scenarios that, when ignited, could affect a nearby building. Examples of other release scenarios include failure of a vapor withdrawal line or service valve, pressure relief valve venting, and liquid withdrawal valve failure. In addition, OSHA’s standard includes a provision for the minimum separation distance between LPG container filling connections, and combustion and mechanical air intakes, to reduce the possibility of ingesting and igniting flammable vapor inside intakes.
Furthermore, OSHA’s standard includes separation distance requirements for installing fixed electrical equipment in hazardous locations to assure control of ignition sources. OSHA concludes that NFPA 58 (2017), Sections 6.28.2 and 6.28.3, do not provide an equivalent level of safety as provided by the greater separation distance (a passive mitigation measure) required in 29 CFR § 1910.110(b)(6)(ii) and Table H-23.