Although stainless steel flanges have unique advantages in materials, even the best things need to be used carefully so that they can be used for a longer period. What precautions should be known for the specific use of stainless steel flanges?
1. To prevent inter-eye corrosion due to the heating of the flange cover, the welding current should not be too large, which is about 20% less than that of carbon steel electrodes, the arc should not be too long, and the interlayers are cooled quickly.
2. The welding rod should be kept dry when used. The calcium-titanium type should be dried at 150°C for 1 hour, and the low-a hydrogen type should be dried at 200-250°C for 1 hour (do not repeat the drying many times, otherwise the coating is easy to crack and peel off), to prevent The electrode coating sticks to oil and other dirt, so as not to increase the carbon content of the weld and affect the quality of the weldment.
3. When welding stainless steel flange pipe fittings, carbides are precipitated after repeated heating, which reduces corrosion resistance and mechanical properties.
4. The chromium stainless steel flange pipe fittings have a large hardening after welding, and the American standard flange is relatively large, which is prone to cracks. If the same type of chromium stainless steel electrode (G202, G207) is used for welding, preheating above 300°C and slow cooling at about 700°C after welding must be carried out. If the weldments cannot be heat treated after welding, stainless steel flange pipe fitting electrodes (A107, A207) should be selected.
5. In Stainless steel flanges, to improve corrosion resistance and weldability, the appropriate amount of stable elements Ti, Nb, Mo, etc. are added appropriately, and the weldability is better than that of chromium stainless steel flanges. When using the same type of chromium stainless steel flange welding rod (G302, G307), it should be preheated above 200 ℃ and tempered at about 800 ℃ after welding. If the weldments cannot be heat treated, stainless steel flange pipe fitting electrodes (A107, A207) should be selected.
The above is a brief introduction to the use of stainless steel flanges, but the specific use process may be more complicated, depending on the situation.
Post time: Mar-31-2023