sanitary drainage or storm drainage facilities;

venting systems; public or private water supply systems;

septic tanks; drainage and supply wells;

swimming pool piping;

irrigation systems; or

solar heating water systems and all appurtenances, apparatus, or equipment used in connection with these, including boilers and pressure process piping and including the installation of water, natural gas (excluding liquid petroleum gases), and storm and sanitary sewer lines; and
water and sewer plants and substations;

the design and installation, maintenance, repair, alteration, or extension of air-piping, vacuum line piping, oxygen line piping, nitrous oxide piping, and all related medical gas systems;

fire line standpipes and fire sprinklers to the extent authorized by law; ink and chemical lines;

fuel oil and gasoline piping and tank and pump installation, except bulk storage plants; and

pneumatic control piping systems