Importance

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Abstract

The method involves injecting into the hollow member adjacent its upper end a body of the material for coating the interior of the member, and then forcing the body of coating material downwardly while forcing an annular portion of the material laterally outwardly into engagement with the walls of the hollow member. This is done by a brush having bristles facing outwardly and of sufficient flexibility to enable them to pass through a stricture of a predetermined degree in the hollow member and to expand when not in such strictures so that at all times the bristles are in close proximity to the inner surface of the hollow member and spread the coating material therealong, pushing the extra coating material ahead to subsequently coat lower portions of the interior of the hollow member. Part of the coating material will escape past the brush to the space thereabove, and when the brush reaches the lower extremity of the hollow member it will be retracted to coat the interior of the hollow member a second time upon upward movement of the brush to the upper end to the hollow member. The means for coating include a brush assembly made up of one or more brushes sized and constructed as above stated, disposed singly or one above the other in multiple, and having a weight connected thereto above or below the brush or brushes, of sufficient density and small enough cross section so that the brush assembly as a whole will move downwardly through the hollow member at a rate greater than would the material for coating the hollow member under the force of gravity alone. Means is provided for retracting the brush assembly after the downward coating trip.

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First Claim