This amendment: (1) increases the maximum allowable operating temperature of thermoplastic pipe from 1000 F to 140 F, (2) prohibits the operation of thermoplastic pipe at a temperature higher than its longterm hydrostatic test temperature, (3) establishes alternative temperature bases for determining the long-term hydrostatic strength of thermoplastic pipe, (4) establishes a single design factor for all plastic pipe, and (5) re- quires that thermoplastic pipe be marked to indicate its long-term hydrostatic strength and related temperature basis. A major benefit of the amendment is that it provides for use throughout the United States and Puerto Rico of properly designated thermoplastic service risers enclosed in metallic casings.