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Three-rod Butterfly Valve Body Casting Welding Production Steps
- Jun 14, 2018 -

Three-rod butterfly valve is a kind of sealed butterfly valve. Butterfly valve body casting is an important part of it. This kind of butterfly valve is widely used in metallurgy, chemical industry, electric power and other industries. It is installed in air and flammable gas pipelines to cut off the gas medium. The three-rod butterfly valve body casting adopts the Q235A steel plate welding structure. After the welding, the welding stress is removed by annealing, and then mechanical processing is performed.


Therefore, in the process of welding the casting of the three-rod butterfly valve body, the process quality thereof is also relatively strict. The main welding process is: preparation before welding → welding → appearance inspection → air tightness test. In the inspection of the weldment, it is mainly to check whether the geometrical dimension of the valve body pair-to-piece meets the pattern design requirements; check whether the welding filler material is consistent with the pattern design; check whether the welding equipment is consistent with the welding technology parameters.


After the welding is completed, the burrs, oil, water, rust, and other contaminants in the welding part of the three-rod butterfly valve body casting must be cleaned in a timely manner so that the welding place exhibits a metallic luster. Note that we must choose the appropriate electrode, welding order is to weld the first layer, the weld position of the weld bead, with the same welding method welding, the valve body all the first layer of the weld should be all welded, First remove the slag, then use a large diameter electrode and a larger welding current for the second layer of welding. The method of transport using a straight line, and a smaller crescent and zigzag shape, and the use of short arc welding.


After the welding is completed, it is also necessary to perform a visual inspection of the welded part of the three-rod butterfly valve body casting. It is usually required that the appearance of the fillet weld be visually smooth with the base material, smooth and beautiful, and there must be no welding defects such as pores, slag inclusions, and undercuts.


Usually before the surfacing treatment is applied on the valve casting of the three-rod butterfly valve body, the burr, oil, water, rust, and other contaminants in the weld bead should be removed. The arc is the same as the general electrode arc welding operation. It is necessary to make marks at the arc starting point to facilitate the final slick lap joint of the multilayer welding so as to ensure the flatness of the surfacing of the butterfly valve body casting.


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