【国外标准】 Standard Practice for Design and Installation of Underground Thermoplastic Irrigation Systems With Maximum Working Pressure of 125 psi (Withdrawn 2010)

This practice establishes the basic design and proper installation procedures for flexible thermoplastic piping systems for underground irrigation systems that operate at maximum working pressures of 125 psi. The thermoplastic pipes shall be made of poly(vinyl chloride) (PVC) or polyethylene (PE), and shall be assembled to withstand the design working pressure for the pipeline without leakage, internal restriction, or obstruction that could reduce line capacity below design requirements. The piping system shall conform to requirements for the working pressure, service factor, system capacity, friction losses, flow velocity, outlets, check valves, pressure-relief valves, and air-release and vacuum-relief valves. The procedures for trench and joints preparation, thrust block construction, line charging, and backfilling are also detailed thoroughly.1.1 This practice establishes procedures for the design and installation of thermoplastic flexible piping systems, for underground irrigation systems. Because there is considerable variability in end-use requirements, soil conditions, and thermoplastic piping characteristics, the intent of this practice is to outline general objectives and basics of systems design, proper installation procedures, and to provide pertinent references.1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units which are for information only and are not considered standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. 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.