These are the skilled craftsmen and craftswomen of Plumbers, Steamfitters & Refrigeration Fitters Local Union #393:

Plumbers

Plumbers are responsible for providing pure water to residential, commercial or industrial buildings, for drinking, cooking, washing, cleaning, manufacturing, or personal use, and for removing waste water.
Plumbing and plumbing fixtures must be installed in accordance with plumbing codes and health and safety regulations.
Plumbing Service and Repair Mechanics

Plumbing service and repair mechanics are responsible for the service, repair and remodeling of existing plumbing systems in residential, commercial and industrial buildings.

Steamfitters

Steamfitters are responsible for designing and installing complex heating systems, special piping for acid, gas, oil, air, oxygen, nitrogen, ultra-high-purity water and gas systems, and other substances.

Refrigeration and Air Conditioning Mechanics/HVAC

Refrigeration and air conditioning mechanics are responsible for the service, repair, installation and retrofit of all types of refrigeration equipment, from the smallest air conditioning systems to the air conditioning and refrigeration units used in hospitals, skyscrapers, research and development laboratories, supermarkets and other complex installations.