What standard applies for underground malleable iron threaded fittings of Class 150?

ASME B16.3 is the specific standard that establishes the requirements for Malleable Iron Threaded Fittings in Classes 150 and 300. NFPA 13, the governing standard for the installation of sprinkler systems, explicitly references ASME B16.3 for this type of component. While the fitting is for underground use, its manufacturing specifications are dictated by its material (malleable iron), type (threaded), and pressure class (150), which are all covered under the scope of ASME B16.3.

A. ASME B16.1: This standard applies to gray iron flanged fittings, not malleable iron threaded fittings.

C. ASME B16.4: This standard applies to gray iron threaded fittings, not malleable iron.

D. ASME B16.5: This standard applies to pipe flanges and flanged fittings, not specifically malleable iron threaded fittings.

1. NFPA 13, Standard for the Installation of Sprinkler Systems, 2022 Edition. Table 7.3.1.1, "Fitting Materials and Dimensions," row for "Malleable Iron."

2. ASME B16.3-2021, Malleable Iron Threaded Fittings, Classes 150 and 300. Section 1, "Scope."

3. Meyer, M. L. (2006). Piping Systems Manual. McGraw-Hill Education. Chapter 3, "Piping System Components," Section on "Malleable Iron Fittings," which references ASME B16.3 for threaded fittings. (This is a widely used academic and professional engineering text).