Method for coating inner faces of metal pipes of small diameter
AssigneeDai Nippon Co., Ltd.
InventorsHaruhiro Kato, Tsunehiko Toyoda, Hiroyuki Tanabe
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Abstract
This invention relates to a method for coating inner faces of metal pipes of a small diameter which comprises feeding a stream of a powdery resin at a rate of 2 to 10 m/sec into a metal pipe of a small diameter preheated at a temperature higher by 20.degree. to 70.degree.C. than the melting or softening point of said powdery resin so that the concentration of said powdery resin or a mixture of said powdery resin and a carrier is 5 to 40% by volume.
Claims4
A method for coating the inner faces of small diameter metal pipes which comprises feeding under pressure a stream of an air or inert gas-diluted powdery mixture composed of 20 to 90 parts by weight of a powdery resin having an average particle size of 5 to 100.mu. and 80 to 10 parts by weight of a carrier having a melting point at least as high as the melting point of said powdery resin and having an average particle size of 150.mu. to 5 mm and from 5 to 100 times greater than the average particle size of the powdery resin, said carrier forming substantially no part of said coating, through the interior of the metal pipe preheated to a temperature 20.degree. to 70.degree.C higher than the melting point of said powdery resin, at a rate of from 2 to 10 m/sec, so that the powdery mixture concentration is 5 to 40% by volume throughout the coating operation.
Dependencies are inferred from the claim text.