| 摘要 |
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.
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