The present invention is directed to a method of cleaning and inspection of drilling mud carrying flow lines, each flow line having an inner surface. The method includes affixing a fitting to the flow line, the fitting having a main flow channel and a branch flow channel extending at an angle from said main flow channel. A first end portion of the fitting can have an attachment that enables connection of the fitting to the flow line at one flow line end portion. A second end portion of the fitting can have one or more doors that can be moved between opened and closed positions, the door or doors providing an opening that is not closed when the doors are in the closed position. A suction line can be connected to the branch flow channel. A cleaning tool can be guided first into the fitting and then into the flow line using a fluid carrying cable. The cleaning tool and jetting fluid can be used to clean drilling mud and debris from the inner surface of the flow line. The jetting fluid can be removed via the branch flow channel using the suction line. The cable can extend through the door opening or openings when the door or doors are in the closed position. A camera can be guided into the flow line using a camera cable wherein the camera cable extends through the door opening or openings. The cleaning tool is preferably too small to fit through the door opening.