MSS SP-123-2018 covers copper and copper alloy unions with metal-to-metal seating, in nominal sizes 1/4 through 4, with solder-joint or threaded end connections, and for use with copper water tube that is compliant with ASTM B88. Included in this Standard Practice are: a. Pressure temperature ratings b. Abbreviations for end connections c. Size and method of designating openings of fittings d. Markings e. Materials f. Dimensions and tolerances g. Tests