초록 ▼

A method of powder coating the inside of tubular goods, such as oil field pipe and the like, by connecting one end of the pipe to a means for producing a flow of compressible gases therethrough. The other end of the pipe is open to atmospheric pressure. A valve means is connected upstream of the pip

A method of powder coating the inside of tubular goods, such as oil field pipe and the like, by connecting one end of the pipe to a means for producing a flow of compressible gases therethrough. The other end of the pipe is open to atmospheric pressure. A valve means is connected upstream of the pipe between the inlet end thereof and a container for holding a single charge of plastic powder. The charge of powdered plastic is isolated upstream of the pipe inlet. The charge is of sufficient size to coat the entire inside peripheral wall surface of the pipe with a substantial uniform coating of plastic. The pipe is heated above the softening temperature of the plastic and rotated so that when the valve is opened air flows through the pipe and establishes a pressure gradient across the entire length of the pipe to cause the captured charge of plastic to form a pocket of dispersed plastic particles which is forced through the pipe by the air flow, causing plastic particles to be deposited and fused to the hot rotating inner surface of the pipe.

대표청구항 ▼

Method of powder coating the interior of a tubular element with a synthetic plastic resin material comprising the steps of: (1) preheating the element to a temperature in excess of the fusion temperature of a plastic resin powder; (2) rotating the preheated element about its longitudinal axis at a s

Method of powder coating the interior of a tubular element with a synthetic plastic resin material comprising the steps of: (1) preheating the element to a temperature in excess of the fusion temperature of a plastic resin powder; (2) rotating the preheated element about its longitudinal axis at a speed which enables any subsequently fused plastic resin to spread into a continuous film; (3) making a pocket-forming apparatus by providing a chamber with an inlet and an outlet; and, connecting one end of the element to the outlet of the pocket-forming apparatus while leaving the other end of the element unobstructed so that flow can occur therethrough; (4) placing a charge of plastic powder within said pocket-forming apparatus; said charge being slightly in excess of the amount of plastic required to uniformly coat the entire interior of said tubular element in a single pass of the charge through the element; (5) forming a pocket of plastic powder which is smaller in volume than the interior of said element and forcing said pocket into the interior of said element by flowing a stream of compressible fluid through the inlet of said pocket-forming apparatus to simultaneously move the entire charge from the chamber into said element, thereby coating the interior of said preheated, rotating element in a single pass; (6) said pocket, as it flows through the interior of said element, is limited to a length which is less than the length of said tubular element.