TECHNICAL MANUAL - Sharq.biz

parallelism and crossingFor parallel routes to urban railway lines, the minimum distance measuredhorizontally between the external surface of the pipeline and the closer railcannot be lower than 0,50 meter.For the crossing of railway lines the laying depth of pipelines cannot be lower than1 meter measured between the upper generatrix of the pipeline and the railwaylevel. Furthermore, the pipeline must be inserted in a prolonged protection pipe,at both crossing sides for at least 1 meter, measured from the external rail.For the water crossing and for the overcoming of slopes, the use of preexistingworkings (bridges, underpasses, ecc) are allowed.In case of overpasses or underpasses with other pipelines, the distance betweenthe surfaces must allow maintenance interventions on both services.bending of pipesAs for gas pipelines, direction changes are allowed also for the polyethylenepipes for water distribution. They take advantage in the flexibility characteristicsof the pipe. Anyway, in order to avoid any excessive stress on the material, it isnecessary to respect the minimum bending radii shown in the following table,valid for temperature of 20°C:SDR pipefrom 7,4 to 17from 21 to 26bending radius≥ 25 d e≥ 35 d e33 ≥ 40 d eIf the requested bending radii are lower, it is necessary to use injection mouldedelbows or segment bends.71