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What are the precautions for using stainless steel flanges

2023-11-21

1. To prevent eye to eye corrosion caused by heating of the flange cover, the welding current should not be too large, which is about 20% less than carbon steel welding rods. The arc should not be too long, and the interlayer cooling should be fast. It is advisable to use a narrow welding pass.


2. When using welding rods, they should be kept dry. Titanium calcium type should be dried at 150 ℃ for 1 hour, while low A hydrogen type should be dried at 200-250 ℃ for 1 hour (repeated drying is not allowed, otherwise the coating may crack and peel off) to prevent the welding rod coating from sticking to oil and other dirt, so as not to increase the carbon content of the welding seam and affect the quality of the welding piece.


3. When welding stainless steel flange fittings, carbides are precipitated due to repeated heating, which reduces corrosion resistance and mechanical properties.


4. After welding, chrome stainless steel flange fittings have a larger hardenability as per American standard flanges, which are prone to cracking. If the same type of chromium stainless steel welding rod (G202, G207) is used for welding, preheating above 300 ℃ and slow cooling treatment around 700 ℃ after welding must be carried out. If the weldment cannot undergo post weld heat treatment, stainless steel flange pipe welding rods (A107, A207) should be used.


5. Stainless steel flanges, with appropriate addition of stable elements such as Ti, Nb, Mo, etc. to improve corrosion resistance and weldability, have better weldability than chromium stainless steel flanges. When using the same type of chromium stainless steel flange welding rods (G302, G307), preheating above 200 ℃ and tempering treatment around 800 ℃ after welding should be carried out. If the weldment cannot undergo heat treatment, stainless steel flange pipe welding rods (A107, A207) should be used.


6. Stainless steel flange fittings and welding rods for welding flanges have good corrosion resistance and oxidation resistance, and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.


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