ACI Committee 376 was formed and subsequently ACI 376-11 was drafted in response to a request from the National Fire Protection Association (NFPA) Technical Committee 59A on liquefied natural gas (LNG). That committee is responsible for NFPA 59A, which is an internationally recognized standard governing the production, storage, and handling of LNG at an operating temperature of –168°C.NFPA 59A contains provisions for the use of reinforced concrete and prestressed concrete for two principal applica-tions: 1) impoundment––secondary containment in conjunc-tion with a metallic primary container; and 2) storage––primary containment.
NFPA 59A is somewhat limited; it does not provide guidelines specifically tailored to concrete use at cryogenic temperatures. This limitation was the impetus for Committee 59A’s request. Although the request was related specifically to containment of LNG, this code addresses concrete use for other refrigerated liquefied gas (RLG) as well, ranging in operating temperatures from +4 to –200°C. This makes the code and commentary analogous to the American Petroleum Institute’s API 620, which governs design and construction of steel and aluminum RLG storage tanks to –168°C.
The most common use of reinforced concrete and prestressed concrete in cryogenic storage applications is for secondary containment around metal primary storage tanks. Prestressed concrete primary containment tanks were built in North America and Europe from the 1960s through the 1980s. Renewed interest in the use of concrete for primary containment and the need for a code that addressed secondary concrete containment led to the development of this code, which includes pertinent excerpts from ACI 318M-11 and ACI 350M-06.
The commentary includes considerations by the committee in developing the code. The commentary is not intended to provide a complete historical background concerning development of the code, nor is it intended to provide a detailed summary of the studies and research data reviewed by the committee in formulating its provisions.