"Certificate of approval" means a document issued and attached to the material, piping, or other location which is completely filled out and signed by the inspector.

"City engineer" means the city engineer or his duly authorized representative.

"Consumer" means any person, persons, customer, firm, association, municipal corporation or corporation that uses gas.

"Distribution system or lines" means and includes the gas pipes, pipe lines, mains, laterals, conduits, feeders, regulators, meters, fixtures, connections and all attachments, appurtenances and appliances necessary and incidental thereto or in any way pertaining to the distribution and use of gas.

"Gas" means natural, artificial and mixed gas.

"Gas company" means any person, firm or corporation holding and exercising a franchise or permit to distribute gas within the corporate limits of the city.

"Gas inspector" means any person authorized by the city engineer to inspect the gas distribution system or lines.