(1)  All piping, including tubing, fittings, gaskets, and packing, shall be made of material suitable for use with nitrogen fertilizer solutions and designed for the maximum pressure to which they may be subjected.

(2)  Screwed joints are permissible provided they are able to withstand maximum pressures to which they are subjected. Pipe joint compounds shall be resistant to nitrogen fertilizer solutions and compatible with materials employed.

(3)  Provision shall be made in the piping system to compensate for expansion, contractions, jarring, vibration and settling.

(4)  After assembly, all piping and tubing shall be tested and proved to be free from leaks at a pressure not less than the normal operating pressure of the system.