Addresses the design and installation of fuel gas systems and gas fired appliances through prescriptive and performance requirements. Key changes include: A new Section was added to recognize arc-resistant CSST products. The code now allows Schedule 10 steel pipe to be used, whereas previously, Schedule 40 was the lightest steel pipe material allowed. Schedule 10 steel pipe joints are allowed to be welded, brazed, flanged or assembled with press-connect fittings. Schedule 10 pipe cannot be threaded. The code clarifies that appliance shutoff valves located behind movable appliances, such as ranges and clothes dryers, are considered to be provided with the required access. The code now calls for the plastic vent pipe material to be labeled as complying with the standards for the specific pipe material as called out by the manufacturer. As an alternative, the plastic pipe can always be listed to UL1738. The clearances between direct-vent appliance vent terminals and openings in the building exterior that could allow combustion products to enter the building have been revised.