Plumbers assemble, install, and repair pipes, fittings, medical gas systems, and fixtures of heating, water, and drainage systems, such as sinks, commodes, bathtubs, water heaters, hot water tanks, garbage disposal units, dishwashers, and water according to specifications and plumbing codes. They locate and mark the position of pipe, pipe connections, and passage holes for pipes in walls and floors using ruler, spirit level, and plumb bob. They cut openings in walls and floors to accommodate pipe and pipe fittings, using hand tools and a threading machine. Plumbers also bend pipe using a pipe-bending machine or by placing pipe over a block and bending it by hand; assemble and install valves, pipe fittings, and pipes composed of various metals or glass, vitrified clay, and plastic; and use hand tools and power tools. Plumbers may weld holding fixtures to structures.
Pipefitters work in the heavy manufacturing industry. They lay out, install, and maintain piping systems that provide steam heat, power, water, hydraulic pressure, air pressure, and oil. They bend, cut, weld, and bracket pipe; repair, pack, and adjust valves; test installed equipment for leaks; and check that the system meets government specifications.