Equipment and supplies Design and construction 7 Air conditioning 4 Heating 4 Maintenance and repair 4 Ventilation 4 Chemical engineering 3 mer ... Chemical plants 3 Fluid dynamics 3 Heat 3 Refrigeration and refrigerating machinery 3 Boilers 2 Chemical process control 2 Chemical processes 2 Chemistry 2 Combustion 2 Condensers (Steam) 2 Data processing 2 Environmental aspects 2 Environmental engineering 2 Heat exchangers 2 Materials 2 Petroleum pipelines 2 Photocatalysis 2 Pipelines 2 Piping 2 Plumbing 2 Pumping machinery 2 Purification 2 Sanitary engineering 2 mindre ...