11 MACHINE PARTS IN THE NATURE OF PLUMBING FITTINGS FOR USE IN BUILDING SERVICES ENGINEERING, GENERAL PLANT ENGINEERING, CHEMICAL PLANTS, PHARMACEUTICAL PLANTS, POWER STATIONS, REFINERIES, SHIPBUILDING, AND IN OFF- AND ON-SHORE FACILITIES, NAMELY, RETURN VALVES, [ REDUCING ] FLANGE RETURN VALVES, [ REDUCING] FLANGE DOUBLE CHECK VALVES, BOTTOM VALVES, DRAIN VALVES, SAMPLING VALVES, [ MULTI-WAY VALVES, EMERGENCY TRIP VALVES, ]WAFER TYPE CHECK VALVES, WAFER TYPE SWING CHECK VALVES, WAFER DUO CHECK VALVES, VACUUM-BREAKING VALVES FOR RELIEVING VACUUM IN CLOSED VESSELS AND PIPELINES, NON-RETURN CHECK VALVES, THERMO-STOP VALVES, HYGIENIC VALVES, HYGIENIC CHECK VALVES, BLANKS AND LINE BLINDS, NAMELY, CIRCULAR PLATES FITTED INTO A PIPELINE IN THE REGION OF A FLANGE CONNECTION USED FOR THE PROVISIONAL CLOSING OF PIPE SECTIONS DURING MAINTENANCE WORK OR WHEN TAKING A PRESSURE READING, SPECTACLE-TYPE BLANKS AND SPECTACLE-TYPE BLINDS, namely, TWO CIRCULAR PLATES CONNECTED BY A BRIDGE AND FITTED INTO A PIPELINE IN THE REGION A FLANGE CONNECTION USED FOR THE PROVISIONAL CLOSING OF PIPE SECTIONS DURING MAINTENANCE WORK OR WHEN TAKING A PRESSURE READING