37 INSTALLATION, MAINTENANCE AND REPAIR OF MARINE SECTOR AND OFF-SHORE GAS AND OIL EQUIPMENT, NAMELY, PISTONS, RINGS, VALVES, CRANKSHAFTS, CRANKCASE AND CYLINDER HEADS, CYLINDERS AND LINERS, COOLER TUBES, BEARINGS, JOINTS, 0-RINGS, FILTERS, CONRODS, RELIEF VALVES AND OIL PUMPS; WEAR RINGS, IMPELLERS, SHAFTS, MECHANICAL SEALS, CASINGS, COUPLINGS, WASHERS, SLEEVES, SPACERS, TOP COVERS, INNER COVERS, BEARING BUSHES AND COUPLING SPACERS; AIR BLOWER UNITS, AIR BLOWER IMPELLERS AND BEARINGS,SHAFT SEALS, DECK WATER SEALS, PRESSURE/VACUUM BREAKERS, OIL AND GAS BURNERS; PARTS OF MACHINES, NAMELY, VALVES, CLACK VALVES, PRESSURE VALVES; HYDRAULIC PRESSURE VALVES, VOLTAGE REGULATING VALVES, COMPRESSORS, STEAM TURBINES AND PUMPS; AIR BLOWER UNITS, AIR BLOWER IMPELLERS AND BEARINGS, SHAFT SEALS, DECK WATER SEALS, PRESSURE/VACUUM BREAKERS, AND OIL AND GAS BURNERS; HOSES AND TUBES, DIFFUSER ELEMENTS, MACERATORS, AIR PUMPS, LEVEL SWITCHES, THERMOSTATS, THERMOCOUPLES AND FILTERS; BULK HEAD PENETRATION ARRANGEMENTS, SHAFT SEALS, SHAFT BEARINGS, GAS SEPARATORS AND GAS AND LIQUID DEWATERING EQUIPMENT; PARTS OF HEATING INSTALLATIONS, NAMELY, THERMOSTATIC VALVES, AIR VALVES FOR STEAM HEATING INSTALLATIONS