The use of trench pipe fittings connection technology, the scene only need to cut machine, groove machine and button bolt with the hand, the construction organization is convenient. But the welding and flange connection, equipped with the complex of power cables, cutting machine, welding machine and oxygen and acetylene gas, etc., it gives the construction organization and brings complexity and there are leakage and fire hazard. Welding and cutting and welding slag, inevitably fall into the internal pipeline, use easy to produce pipeline valve or even blocking of the equipment, water pollution tube.
         In addition, welding and flange connection inevitably requires long periods of high strength of the work, but also prone to production safety accidents.