ASME B31.1 prescribes minimum requirements for the design, materials, fabrication, erection, test, inspection, operation, and maintenance of piping systems typically found in electric power generating stations, industrial and institutional plants, geothermal heating systems, and central and district heating and cooling systems. It also covers boiler-external piping for power boilers and high-temperature, high pressure water boilers in which steam or vapor is generated at a pressure of more than 15 psig; and high temperature water is generated at pressures exceeding 160 psig and/or temperatures exceeding 250 degrees F. Key changes to this revision include: Now mandatory: rules for nonmetallic piping and piping lined with nonmetals; Cold-forming rules for creep strength enhanced ferritic steels have been incorporated into Chapter V Fabrication, Assembly, and Erection; Chapter VII Operation and Maintenance revised to include requirements for: documentation of dynamic events piping and pipe-support maintenance programs and personnel requirements; Preheat and post-weld heat treatment rules have been reformatted into tabular form for clarity. It is the owner’s responsibility to select the B31 Code Section(s) that apply to a proposed piping installation. For some installations, more than one Code Section in the B31 series may apply to different parts of a piping system or to different parts of the installation. ASME B31.1 is one of ASME’s most requested codes, widely adopted by jurisdictions worldwide. It is prominently referenced in ASME’s Boiler and Pressure Vessel Code, Section I. This Code serves as a companion to ASME’s B31.3 Code on Process Piping as well as to the other codes in ASME’s B31 series. Together, they remain essential references for anyone engaged with piping.