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Precautions for welding stainless steel pipe fitting

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1. To prevent corrosion due to heating, the welding should not be too long, which is about 20% less than that of carbon steel electrodes. The arc should not be too long, and the layers will cool quickly. A narrow weld bead is preferred.
2. Stainless steel pipe fittings harden quickly after welding and are prone to cracks. When welding with typical stainless steel pipe fittings, preheating above 300°C and slow cooling at about 700°C after welding is necessary. If the weldment cannot undergo post-weld heat treatment, stainless steel pipe fitting electrodes should be used.
3. Stainless steel pipe fittings, to improve the corrosion resistance and weldability, appropriate amounts of stable elements Ti, Nb, Mo, etc. are added. The weldability is better than that of stainless steel pipe fittings. When using the same type of chromium stainless steel welding rod, preheating above 200°C and tempering treatment at about 800°C after welding should be carried out. If the weldment cannot be heat treated, chromium-nickel stainless steel welding rods should be used.
4. Stainless steel pipe welding rods have excellent corrosion resistance and oxidation resistance and are widely used in the chemical industry, fertilizer, petroleum, and medical machinery manufacturing.
5. The coatings for stainless steel pipe fittings are available in calcium titanium type and low hydrogen type. Calcium titanium type can be used for AC and DC, but the penetration depth is shallow during AC welding and it turns red at the same time, so connect it to a DC power source as much as possible.
6. Stainless steel pipe fittings have certain corrosion resistance (oxidizing acids, organic acids, cavitation), heat resistance, and wear resistance. It is usually used as equipment materials in power stations, chemical industries, petroleum, etc. Stainless steel pipe fittings have poor weldability, so attention should be paid to the welding process and appropriate welding rods should be selected before heat treatment.
7. The welding rod should be kept dry when used. The titanium-calcium type should be dried at 150°C for 1 hour, and the low-hydrogen type should be dried at 200-250°C for 1 hour (cannot be dried multiple times, otherwise the coating will easily crack and peel off). Pay attention to the welding rod. The coating will stick to oil and other dirt, so as not to increase the carbon content of the weld and affect the quality of the weldment.
8. When welding stainless steel pipe fittings, carbides will precipitate due to repeated heating, reducing corrosion resistance and mechanical properties.




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