... of crane travelling mechanism, hoisting mechanism, jib lubbing mechanism, huge steel beam, box structure, welding rack, welding cavity, unique welding structures, winch drums ... structure's machining. Usually in welde structural steel, carbon steel, low alloy steel, even stainless steel, which with good welding performance.There are ... MPI, complying with ASTM,AWS,ISO,EN. TPI also acceptable. Steel beam