Pipefitters fabricate, assembles, and installs piping systems. When assigned a project, the pipefitter chooses the appropriate materials and size of the pipes, then manipulates the metal to fit the installation area by using techniques such as threading, welding, grinding, rigging, cutting, bending, and soldering. Pipefitters are also responsible for transporting the pipes, installing them, and testing the system to ensure it runs properly. At the commercial level, these systems are typically heating and cooling systems, but pipefitters may also work with plumbing and water systems.