Analyze the gap in the production process of domestic valves and foreign valves-the gap in processing technology
Gaps in processing technology
In the welding process, in order to meet the radiation resistance requirements of the sealing materials of nuclear valves, KSB has widely used special solder powder for cobalt-free welding; the French Welan Valve Company will preheat, automatic welding, and post-weld treatment in The same equipment or the same production line is completed, regardless of the pre-welding, welding, and post-welding treatments, the temperature can be automatically controlled to ensure the welding quality.
However, the domestic valve welding technology is backward, and some still use outdated welding methods, the welder's technical level is low, and the welding materials are also ordinary materials, which cannot meet the design requirements of special valves. Many companies are busy with production and sales all day, and seldom conduct research and improvement on the process.
In the application of the new technology of die forgings, German KSB company mainly produces high-temperature alloy steel F91 and F22, and high-pressure valves are mainly forged parts, which ensures the reliability and economy of the products. Die forging is used for gate valves below 600Lb in large batches, and welding is carried out. The valve does not have many defects such as porosity and looseness due to casting, and greatly reduces the material waste of free forging, and the economy is greatly improved.
In the domestic industry, most of the valve blanks are castings, and die forging is rarely used. Valve die forging with high pressure below 600Lb is even rarer. In order to reduce costs, many companies in this regard mostly use steel castings, and low-pressure ones use more cast irons, with low material costs and simple processing techniques.