1.1.1 This practice assumes that over the range of anticipated operating conditions, including maximum external loading and minimum internal pressure, the soil/pipe system will offer sufficient structural stability to resist possible excessive diametrical deformation, or even collapse. It is beyond the scope of this practice to describe these procedures in detail since it is recognized that significant differences exist in their implementation depending on kind and type of pipe material, pipe size and wall thickness, soil conditions, and the specific end use. Scope 1.1 This practice governs procedures and references ASTM specifications for underground installation of thermoplastic pressure piping, 63-in. Specific precautionary statements are given in Sections 10 and 11.ġ. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. 1.2 The values stated in inch-pound units are to be regarded as the standard. Soils in which trenches are dug shall be examined and identified and the trenches prepared and backfilled in accordance with sound bedding procedures and this practice. However, proper installation techniques are required to ensure that the necessary support at the bottom and passive soil pressures at the sides of the pipe are developed and maintained. This flexibility allows ductile thermoplastic pipe to activate through pipe deformation lateral soil forces which create a pipe/soil system capable of safely supporting–even in pipes subject to little or no internal pressure–the earth and superimposed loads which are encountered in most pipe installations. Piping made from such materials has the ability to bend under a load without breaking and to deform in other ways, while offering continued resistance. In general, thermoplastics pressure piping materials behave as ductile materials under load, meaning that they can undergo considerable deformation without damage. This standard has been approved for use by agencies of the Department of Defense. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. A number in parentheses indicates the year of last reapproval. Underground Installation of Thermoplastic Pressure Piping1 This standard is issued under the fixed designation D 2774 the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision.