Xiamen Dervos Valves Industry Co., Ltd

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Defective Valve Castings
- Jan 23, 2017 -

1, deficiency judgment
In practice, some of the casting defect repair welding is not allowed, such as through cracks, penetration defect (end of wear), honeycomb-shaped holes, failed to clear sand of slag and area of more than 65cm2 such as shrinkage, and other cannot contract the repair of major defects. In front of the weld should determine the type of defect.
2, defect removal
Carbon arc gouging can be used in a factory defects to blow, and then with a hand-held angle grinder grinding defects to reveal metallic luster. But more directly in production using carbon steel electrode electric current to remove defects and angle grinder grinding metallic luster. General casting defects removed <4mm-J422 electrode, 160~180A current, defects in addition to clean, angle grinder will defect into u-shape, reduced welding stress. Defect removal and complete, weld quality.
3, defective parts preheating
Carbon steel and austenitic stainless steel castings, welding parts of area <65cm2, depths < casting thickness of 20% or 25mm, usually without preheating. ZG15Cr1Mo1V, ZGCr5Mo, Pearlite steel castings, steel hardened, cold welding crack, preheating, preheating temperature is 200~400℃ (with stainless steel electrode welding, small value of temperature), time should not be less than 60min. If the casting is not overall warming, oxy-acetylene heating after the defective parts and extend 20mm to 300-350 c (background Visual observation of dark pale red), big torch neutral flame guns on the flaws and fast swing around in a circle for a few minutes, then into a slow move to keep 10min (depending on the thickness and defects), defects after fully preheated, rapid repair.