Machining tool and method for double-wall gas pipe of marine diesel engine

The invention discloses a machining tool and method for a double-wall gas pipe of a marine diesel engine, the machining tool comprises a base, a fastening supporting piece, a pressing plate, a fastening bolt and an adjusting supporting piece, firstly, interface flanges are welded to pipe openings of all through pipes of the double-wall gas pipe, and one machining tool is clamped on each interface flange; then all the machining tools are fixed to a working table of a machine tool, the pressing plate and the fastening supporting piece stably clamp the interface flanges from the upper direction and the lower direction, the adjusting supporting piece is used for adjusting the height of the pressing plate, and the flange faces of all the interface flanges are sequentially cut and machined one by one through the machining tool; it is ensured that the flange face is perpendicular to the axis of the through pipe of the double-wall gas pipe. The process scheme that the interface flange is welded firstly and then the f