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Gantry Crane Welding Repair Technology

Jul 28, 2017
The key technology of gantry crane welding repair is to avoid hot cracking and cold cracking. The way to prevent cracks during welding is to reduce the diffusion of hydrogen content, reduce the harden tendency and heat input, reduce the welding stress and so on.
 
1. Opening. Respectively open the V-shaped groove at the both side of tooth root and cast steel base combination, the depth is about 12mm.
 
2. Selection of welding material. In order to reduce the content of diffused hydrogen, the J557 welding rod with low hydrogen and good crack resistance is good selection for the welding material.
 
3. Gantry crane welding process. The bottom should select 3.2mm J557 welding rod, welding current 110A, the other layers use 4mm J557 welding rod, current 130 ~ 160A, the power supply polarity apply DC reverse.
 
4. Welding. The J557 welding rod should bake at 350 ℃ temperature for 1 hour  before welding, warm up the welded parts to 300 ℃ or so  with the flame, apply the arc welding, multi-layer multi-channel welding. (Note: the gantry crane should be coated with yellow mud with remaining non-welding surface). The welding rod should be hammered as soon as welded in order to eliminate stress, each weld should be hammered. During welding, the interlayer temperature is not less than 300 ℃, after welding, should cover with asbestos cloth to keep warm for 8 hours, the use the  angle grinder to clean and repaire the welding point.

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