Refrigerator Water Tube Nut, 1/4-in. This water tube nut (part number WR57X57) is for refrigerators.Water tube nut WR57X57 connects lines to fittings such as the water valve or water line connectors.Safely store any food that could deteriorate while the power is off, unplug the refriger... - Refrigerator Water Tube Nut, 1/4-in.