TECHNICAL MANUAL - Sharq.biz

installationof PE pipelinesThe polyethylene differs from traditional materials used for pipelines carrying fuel gasand fluids under pressure for its particular physical and mechanical characteristicsof high flexibility and ductility. If in the past these characteristics were considereda performance limit the same are now an advantage allowing the laid pipelines tosupport the ground stress. If the laying and covering conditions are controlled,especially for the ground compressing, the use of PE pipes allow a greaternetwork safety in case of ground settlings, landslides or earthquakes. Furthermorethe PE pipelines flexibility allow the use of innovative laying technologies withimportant reduction in times and laying network costs. The PE lightweight and theeasy weldability give advantages in terms of speed of the laying operations.gas pipelinesgas pipeline classificationThe Decree of the Economic Development Ministry 16 th April 2008 classifies thepipelines relative to the natural gas distribution with density not higher than 0,8within seven different types, characterized from decreasing values of the maximumworking pressure (MOP) from 1 st up to 7 th type. For the materials and the productsto be used in the construction of the distribution systems, the Decree refers to thestandard UNI 9034, which allows the use of polyethylene pipes, fittings and specialjoints for pipelines with maximum working pressure lower or equal to 5 bar:typemaximum working pressure (MOP)4 th 1,5 bar < MOP ≤ 5 bar5 th 0,5 bar < MOP ≤ 1,5 bar6 th 0,04 bar < MOP ≤ 0,5 bar7 th MOP ≤ 0,04 barexcavationThe polyethylene pipes for the gas distribution must be normally used forunderground pipelines. The minimum buried depth defined by the standardUNI 9165, calculated from the upper generatrix of the pipe at ground level, isaccording to the pipeline type, to the laying area and to the laying conditions, asdetailed in the following table.pipeline typelaying areanotes4 th and 5 th 6 th and 7 thRoadway 0,90 m 0,60 mAreas without vehicle traffic(i.e. flowerbeds, pavements, traffic islands, city green areas)0,40 m 0,40 mCountry lands 0,90 m 0,60 mRocky soils 0,40 m 0,40 mOnly if the pipeline is laid at least 0,50 m fromroadway borderA buried depth with minimum of 0,50 m isallowed near to undulations, drainage ditch,bumps and similars fro short distancesInstallationof PEpipelines67