Underground gas piping shall be installed with sufficient clearance from any other underground structure to avoid contact therewith, to allow maintenance, and to protect against damage from proximity to other structures. In addition, underground plastic piping shall be installed with sufficient clearance, or shall be insulated from any source of heat so as to prevent the heat from impairing the serviceability of the pipe.
Protection Against Damage: Means shall be provided to prevent excessive stressing of the piping where there is heavy vehicular traffic, or soil conditions are unstable and settling of piping or foundation walls could occur. Piping shall be buried or covered in a manner so as to protect the piping from the physical damage. Piping shall be protected from physical damage where it passes through flower beds, shrub beds, and other such cultivated areas where such damage is reasonably excepted.
Protection Against Freezing: Where the formation of hydrates or ice is known to occur, piping shall be protected against freezing.
Piping Through Foundation Wall: Underground piping, where installed below grade through the outer foundation or basement wall of a building, shall be encased in a protective pipe. The annular space between the gas piping and the sleeve shall be sealed at the foundation or basement wall to prevent entry of gas or water.
Piping Underground Beneath Buildings: Where the installation of gas piping underground beneath buildings is unavoidable, the piping shall be encased in an approved conduit designed to withstand the superimposed loads. The conduit shall extend into a normally usable and accessible portion of the building and, at the point where the conduit terminates in the building, the space between the conduit and the gas piping shall be sealed to prevent the possible entrance of any gas leakage. If the end sealing is of a type that will retain the full pressure of the pipe, the conduit shall be designed for the same pressure as the pipe. The conduit shall extend at least 4 in. (10 cm) outside the building, be vented above grade to the outside, and be installed so as to prevent the entrance of water and insects.