PURPOSE: To prevent excess spraying and to eliminate the need for cleaning a threaded section adjacent to a coated threaded section by making a gaseous stream act as a mask to prevent the contact of pneumatrically transported powder with the second part of a pipe and forming a distinct boundary line with the first threaded end subjected to powder coating.
CONSTITUTION: While the powder is sprayed from a main nozzle 20 and an auxiliary nozzle 42, high-pressure air is discharged from nozzles 66, 68 toward the threaded section 82 directly adjacent to the endmost part 14 of the pipe 16. These air streams substantially function as the mask to prevent the contact and deposition of the excess spray powder with and to the surface of the threaded section 82 adjacent to the endmost threaded section 14 of the pipe 16. The deposition of the powder on the threaded section 82 adjacent to the surface of the coating part 14 of the pipe 16 is averted in such a manner, by which the sufficient electrical contact is assured between the non-coated threaded section 82 of the pipe 16 and a pipe joint for serially connecting the two pipes.
RARII DABURIYU KIIFUAA
TERENSU EMU FUARUKAASON
KENESU DABURIYU GUREI
