This specification covers plastic insert fittings for polyethylene (PE) plastic pipe. The fittings shall be made from one of the following plastics: nylon plastics, propylene plastics, and poly(vinyl chloride) plastics. Dimensions and burst pressure for the fittings should meet the requirements specified. The fittings shall be homogeneous throughout and free of cracks, holes, foreign inclusions, or other defects. The fittings shall be as uniform as commercially practicable in color, opacity, density, and other physical properties.