Bent supply piping shall have the bends smoothly made without any appreciable reduction in cross-sectional area and shall have no imperfection occasioned by the bending process.

Gas supply piping, tubing and fittings shall be rigidly supported with pipe hooks, metal pipe straps, bands or hangers suitable for the size of the piping or tubing. Gas piping shall not be supported by other piping.

Gas supply piping to which connections are made for burners, pilots, lighters or other branch supply lines shall be so assembled and rigidly supported as to prevent turning or displacement in making connections to the building piping or in the ordinary handling of the unit.

Compounds used on threaded joints of gas piping shall be resistant to the action of liquefied petroleum gases.

Connections for pilot gas supply lines shall be so located that pilot lines of semi-rigid tubing and pilot valves will not be unnecessarily exposed to damage hazards.

When iron pipe is used for pilot burner manifolds, its nominal size shall be not less than one quarter inch, and when used for individual pilot lines its nominal size shall be not less than one-eighth inch.

When semi-rigid tubing is employed as gas conduit, it shall be not less than nominal one quarter inch size.

Aluminum semi-rigid tubing shall not be exposed to condensate or to temperatures in excess of 700° F. Aluminum semi-rigid tubing shall not be used to pass through insulating material of other than neutral reaction unless the tubing is adequately protected from the insulation.

Unions in gas lines for use with liquefied petroleum gases or LP gas-air mixtures shall be either of the ground joint type or a flanged joint having packing resistant to the action of such gases.

A one-eighth inch I.P.S. plugged tapping accessible for test gage connection shall be furnished downstream from the last main line gas control for measuring gas pressure at the burner. The plug used shall not be of the slotted head type.