49 CFR § 192.321 - Installation of plastic pipe.
(a) Plastic pipe must be installed below ground level except as provided in paragraphs (g), (h), and (i) of this section.
(c) Plastic pipe must be installed so as to minimize shear or tensile stresses.
(e) Plastic pipe that is not encased must have an electrically conducting wire or other means of locating the pipe while it is underground. Tracer wire may not be wrapped around the pipe and contact with the pipe must be minimized but is not prohibited. Tracer wire or other metallic elements installed for pipe locating purposes must be resistant to corrosion damage, either by use of coated copper wire or by other means.
(f) Plastic pipe that is being encased must be inserted into the casing pipe in a manner that will protect the plastic. Plastic pipe that is being encased must be protected from damage at all entrance and all exit points of the casing. The leading end of the plastic must be closed before insertion.
(1) The operator must be able to demonstrate that the cumulative aboveground exposure of the pipe does not exceed the manufacturer's recommended maximum period of exposure or 2 years, whichever is less.
(2) The pipe either is located where damage by external forces is unlikely or is otherwise protected against such damage.
(3) The pipe adequately resists exposure to ultraviolet light and high and low temperatures.
(1) Installed with protection from mechanical damage, such as installation in a metallic casing;
(2) Protected from ultraviolet radiation; and
(i) Plastic mains may terminate above ground level provided they comply with the following:
(1) The above-ground level part of the plastic main is protected against deterioration and external damage.
(2) The plastic main is not used to support external loads.
(3) Installations of risers at regulator stations must meet the design requirements of § 192.204.