A gas fitter handles the installation, maintenance, and repair of natural gas pipes for residential, commercial, and industrial buildings. You may work as a gas fitter for utility companies, gas companies, or the construction industry. As a gas fitter, your job duties include installing gas equipment like valves, burners, regulators, and meters, testing and servicing equipment, installing gas lines for appliances like boilers, stoves, ovens, and barbeque grills, and repairing pipes and fixtures. Your job may call for other tasks, like working on underground gas mainlines.