text: Pipefitters should not be confused with pipelayers. Both trades involve pipe and valves and both use some of the same tools. However, pipelayers usually work outside, laying pipe underground or on the seabed, whereas pipefitters typically work inside, installing piping in buildings, aeroplanes, or ships. One author summarizes the different tasks this way:
  <blockquote><poem>Pipe layers operate the backhoes and trenching machinery that dig the trenches to accommodate the placement of sanitary sewer pipes and stormwater sewer drainpipes. They use surveyor’s equipment to ensure the trenches have the proper slope and install the pieces of pipe in the trenches, joining the ends with cement, glue, or welding equipment. Using an always-open or always-closed valve called a tap, pipe layers connect them to a wider system and bury the pipes.
  Pipe fitters plan and test piping and tubing layouts; cut, bend or fabricate pipe or tubing segments; and join those segments by threading them, using lead joints, welding, brazing, cementing, or soldering them together. They install manual, pneumatic, hydraulic and electric valves in pipes to control the flow through the pipes or tubes. These workers create the system of tubes in boilers and make holes in walls and bulkheads to accommodate the passage of the pipes they install.