A coating apparatus for coating the interior surface of a relatively long, narrow pipe without any portion of the apparatus contacting the interior of the pipe has been provided, and comprises a mobile vehicle carrying a traveling boom on which is mounted a coating or spraying device for coating the pipe, an adjustment mechanism for moving the boom relative to the vehicle and to align the boom with the pipe, and a driving and supporting mechanism for the boom which drives and also supports the boom as it moves into and out of the relatively long, narrow pipe. In addition, several alternative embodiments of spraying devices for the coating apparatus are disclosed which eliminate or reduce "ghosting" or "shading" problems frequently experienced in coating such pipe.