1.1 This specification covers metal insert fittings and copper crimp rings for use with cross-linked polyethylene (PEX) tubing in ³/₈ , ¹/₂ , ⁵/₈ , ³/₄ , 1, 1 ¹/₄ , 1¹/₂ , and 2 in. nominal diameters that meet the requirements for Specification F876 or F3253 and for use with polyethylene of raised temperature (PE-RT) tubing in ³/₈ , ¹/₂ , ⁵/₈ , ³/₄ and 1 in. and 1 ¹/₄ in. nominal diameters that meet the requirements of Specifications F2623 and F2769. These fittings are intended for use in 100 psi (689.5 kPa) cold- and hot-water distribution systems operating at temperatures up to, and including, 180 °F (82 °C). In addition, the fittings covered by this specification are intended for use in, but not limited to, residential and commercial systems, reclaimed water, fire protection, municipal water service lines, radiant heating and cooling systems, hydronic distribution systems, snow and ice melting systems, geothermal ground loops, district heating, turf conditioning, compressed air distribution and building services pipe. The requirements for materials, workmanship, dimensions, and markings to be used on the fittings and rings are also included.