Heat exchangers, being parts of machines; steel constructions, namely, steel frames in the nature of mounting brackets adapted for use with heat exchangers and heat exchanger blocks being parts of machines

Heat exchangers, heat exchanger tubes and structural and replacement parts therefore, pressure vessels, namely, hot water heaters and industrial boilers

HEAT EXCHANGERS, HEAT EXCHANGER TUBES AND COMPONENTS THEREFORE, PRESSURE VESSELS, NAMELY, HOT WATER HEATERS AND INDUSTRIAL BOILERS