Standpipes: Protecting Horizontal Pipe What are Laterals? ROLAND J. HUGGINS, PE | American Fire Sprinkler Association
One of the aspects of NFPA 14, Standard for the Installation of Standpipe and Hose Systems, that has been regularly edited over the last several cycles of the standard is the protection of piping against fire damage. This article will look at these changes with a particular focus on laterals. It will also limit the discussion to Class I standpipes. The reason for this article is that although NFPA 14 is in pretty good shape, the driving force—that being the International Building Code (IBC)—is not yet as well defined. Let’s start with the portion of the IBC that addresses protection of the pipe. Section 905.4.1 states: “Protection. Risers and laterals of Class I standpipe systems not located within an interior exit stairway shall be protected by a degree of fire resistance equal to that required for vertical enclosures in the building in which they are located.” There’s then an exception that states: “In buildings equipped throughout with an approved automatic sprinkler system, laterals that are not located within an interior exit stairway are not required to be enclosed within fire-resistance-rated construction.” Seems simple enough except there’s no definition for lateral. IBC also directs us when no definitions are provided to do as follows: “ ... such terms shall have ordinarily accepted meanings such as the context implies... ” This is the same guidance provided by the NFPA standards except they take an additional step and state: “Merriam-Webster’s Collegiate Dictionary, 11th edition, shall be the source for the ordinarily accepted meaning.” In checking Merriam-Webster, we’re told that a lateral means “a branch from the main part (as in an irrigation or electrical system).” This seems to support the text in the IBC commentary (the equivalent to the Sprinkler Handbook for NFPA 13) that define laterals as “ ... and laterals (i.e., the horizontal segments of standpipe system piping)… ” The problem, though, is that the definition states that it’s a pipe section from the main part (aka the standpipe) and parts of the system go to the main part such as feed mains. Before diving this deep into the nuances of the English language (which we code nerds are supposed to do), keep in mind that for many years the feed main was not required to be protected. Even more of a problem is that historically NFPA 14 had a specific use for the term lateral. So, let’s now delve into the history of NFPA 14 regarding the protection of piping, and this thing called a lateral. 16 Sprinkler Age | September/October 2019
In the 1978 edition of NFPA 14 (13 cycles or 41 years ago), all it said was: “3-3.2 Standpipes shall be so located that they are protected against mechanical and fire damage.” No guidance is given on what that applies to or how to accomplish it. Other interesting items are you could have a single standpipe in smaller buildings (the driving criteria was “… that all portions of the building are within 30 ft of the nozzle when attached to not more than a 100-ft hose”), the minimum pressure for a Class I system was 65 psi, and locating the standpipe in the exit stairway was a recommendation in the annex. The body of the standard simply says to place the hose station, so it is conspicuous and not likely to be obstructed. The only use of lateral was in the annex for this section where it stated: “A-4-1.1 Hose may be located at one side of the standpipe and supplied by short lateral connections to the standpipe where necessary to avoid obstructions.” In other words, it’s in the immediate area of the standpipe. Let’s jump 18 years to the 1996 edition of NFPA 14. We’re now in more familiar country. There’s the placement within all required stairways (though it is interesting that the same annex material from the 1978 edition remains, saying they should be in stairways) along with adjacent to openings in horizontal exits. There’s also the now common 100 psi minimum pressure. Surprisingly, the 100-ft hose and 30-ft throw criterion are gone, having been replaced with a travel distance (though it lives on in the IBC so you must still be aware of it—but that’s a design issue). Feed mains (defined as: “that portion of standpipe system that supplies water to one or more standpipes”) and branch lines (defined as “a piping system, generally in a horizontal plane, connecting one or more hose connections with a standpipe”) have also been explicitly identified. It’s worth noting that branch line started as feeding more than one hose connection. More pertinent to the focus of this article is that explicit guidance on protection is provided. Section 4-1.2.2. states: “Standpipes and lateral piping SUPPLIED BY standpipes shall be located in enclosed exit stairways or shall be protected by a degree of fire resistance equal to that required for enclosed exit stairways in the building in which they are located.” This requires just the standpipe (aka vertical risers) and the horizontal feeds to hose connections (as indicated by the capitalized phrase “supplied by”) to be protected. It’s interesting to note that this section did not use the new term branch line. There is also an exception when the building is sprinklered that lateral piping to 21/2-in. hose connections is not required to be protected.