Monday, August 18, 2014

Mechanical expanding and hydraulic expanding characteristics

(1) the production of large diameter steel pipe aging rate. Because when you need to charge hydraulic expanding low-pressure water and then pressurized to achieve further boost when the steel yield. With the production of pipe diameter increases, the efficiency is greatly reduced, for example, pipe length 12m dollars, when 609.6mm (24in) diameter steel pipe hydrostatic expansion, 36 per hour, while the mechanical expanding, each Hour 28. Right 1067mm (42in) steel pipe, expanding the use of water pressure, 18 per hour, while 23 per hour when mechanical expanding. That mechanical expanding, not its efficiency and diameter size relationship, so relatively speaking diameter increases, the efficiency also high.

(2) easy to meet the stringent requirements of the inner diameter of the pipe. When laying long-distance pipelines, welded steel pipes installed in the field site, with an inner diameter of the base, the smaller inner diameter of the wrong side of two steel tube end after docking, transport resistance also smaller, so the pipe inner diameter of the dimensional accuracy requirements increasingly stringent, and the pressure outside the enlarged diameter of the die case is precisely controlled with pipe diameter, the inner diameter accuracy can not be guaranteed. Mechanical expanding head is inserted into the expanded diameter steel pipe were expanding, therefore, can control the pipe diameter size precision, regardless of wall thickness.

(3) good ovality. When the pressure expanding, because contact with the outer mold outer sleeve seam to the wall near the depression, the degree of damage to the oval steel tubes. When the expanding machine, as long as the weld head aligned with the enlarged diameter groove segments, expanded diameter when unconstrained weld area to form a smooth surface, thus effectively reducing the damage caused by the welded parts.

(4) the shape and size of the pipe end and high accuracy. Weld expanding effect when compared to both ends of the pipe need to push the conical indenter pressed against the head set in radial seal ring seal up, so steel tube end portion of the indenter in contact with the pipe flaring effect the tubular body portion inconsistent. The expanding does not have this phenomenon, good shape and size of the pipe end of the Field Installation and butt are favorable.

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