TECHNICAL MANUAL - Sharq.biz

gas and water pipeline layingThe installation procedures must be carried out by expert operators.The pipes must be laid either altimetrically or planimetrically in the exact positionas shown in the project drawings, unless otherwise suggested by the WorksDirection.The single pipelines made outside the excavation must be laid inside the trenchusing ropes or hemp/nylon or similar materials bands, avoiding possible scrapingon the soil or on the trench edge. The pipe sections with external surface cutswith depth exceeding 10% of their thickness must be cutted off.Control devices such as valves and gate valves which can stress the pipes dueto their weight must be hold by independent supports avoiding any stress on thepipeline and on the jointings.laying bed and filling upThe pipelines laid on the bottom of the excavation must have stable support onthe bottom of it along the whole lower generatrix and along its whole length. Toachieve this the trench base must be flat, made by an uniform material in orderto avoid possible mechanical stresses to the pipe.If on rocky, gravelly or with filling material soils, the trench bottom must be leveledwith sand or other material with similar granulometric characteristics. Anywaythe polyethylene pipelines must be always laid on a proper bed made of sand orriddled soil with thickness higher than 10 cm. The pipeline must be protected onits whole circumference with the same material suitably compressed.When the pipeline is finally laid in the trench, it must be covered with a layer ofsand not lower than 10 cm, measured from the upper generatrix of the pipe.The compacting of the layer till about 2/3 of the pipe must be particularly cared,made manually avoiding any movement of the pipe. The compressed sand mustbe of good consistency and uniformity, covering the pipe on each side.72