The Materials Transportation Bureau (MTB) is considering amendments to the requirements of §§ 192.121 and 192.- 123(b) (2) which" prescribe the design pressure and maximum allowable operating temperature of plastic pipe used in gas pipelines. The amendment to § 192.121 would establish (1) for thermoplastic pipe, alternative temperature bases for determining the long-term hydrostatic strength used in computing pipe design pressure, and (2) a single design factor for use Irk the design formula for plastic pipe. The amendment to § 192.123 (b) (2) would prohibit the use of thermoplastic pipe where operating temperature of the pipe will exceed the temperature used as a basis for determining long-term strength under § 192.- 121. In addition, the marking requirements of § 192.63 would be amended to require that thermoplastic pipe be marked to state its long-term hydrostatic strength and related temperature basis.