| 摘要 |
PURPOSE:To make it possible to apply a polypropylene lining in a very simple manner by first, spraying polypropylene powder over the inner surface of a carbon steel pipe which is heated and thus melting the powder, and cooling the molten polypropylene to become hardened after sealing a pressurized gas into the pipe. CONSTITUTION:For example, first the inner surface of carbon steel pipe with an internal diameter of 4'' and a length of 200mm is cleaned by blast process, then this pipe is heated at 250+ or -20 deg.C, and, for example, polypropylene powder with an average grain diameter of 100mum is sprayed so that the thickness of a lining is 2mm. In addition, the powder is thermally molten, flanges 2, 2 and a pressurized gas feed pipe 3 are installed on both ends of the pipe 1, and further, for example, nitrogen gas is pressurized and sealed into the pipe 1 at a specified pressure. Thus the powder is cooled to become hardened and thereby the carbon steel pipe lined with polypropylene is prepared. Consequently, the contraction and stress concentration of polypropylene during the cooling/ hardening process, are moderated by sealing the pressurized gas into the pipe, so that the generated polypropylene lining can be prevented from peeling off. |
