Common precautions in welding of stainless steel pipe fitting tee

　　1. In order to prevent the corrosion between clear and bright due to heating, the welding current should not be too sticky, 20% less than that of carbon steel electrode, the arc should not be too long, and the interlayer cooling should be fast, and the narrow weld bead is suitable.

　　2. The hardening of stainless steel pipe fitting tee is sticky after welding and easy to crack. If the welding of typical stainless steel pipe fitting tee is accepted, preheating above 300 ℃ and slow cooling treatment at 700 ℃ after welding are necessary. If the weldment cannot be post weld heat treated, stainless steel pipe fitting tee welding rod shall be selected.

　　3. The weldability of stainless steel pipe fitting tee is better than that of stainless steel pipe by adding appropriate amount of invariant elements Ti, Nb, Mo to improve corrosion resistance and weldability. When accepting the same typical chromium stainless steel electrode, it should be preheated above 200 ℃ and tempered at 800 ℃ after welding. If the weldment cannot be heat treated, chromium nickel stainless steel electrode shall be used.

　　4. Stainless steel pipe fitting tee welding rod with exquisite corrosion resistance and oxidation resistance is widely used in chemical industry, chemical fertilizer, petroleum and medical machinery manufacturing.

　　5. The coating of stainless steel pipe fitting tee has titanium calcium type and low hydrogen type. The titanium calcium type can be used for AC and DC welding, but the penetration is shallow during AC welding, and it is convenient for reddening. Therefore, DC power supply is generally accepted.

　　6. Stainless steel pipe fitting tee have certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance and wear resistance. Generally used for power station, chemical industry, petroleum and other equipment and materials. Due to poor weldability of stainless steel pipe fittings, attention should be paid to welding process and selection of suitable electrode before heat treatment.

　　7. The welding rod shall be kept dry during operation. The titanium calcium type shall be dried at 150 ℃ for 1 hour, and the low hydrogen type shall be dried at 200-250 ℃ for 1 hour (repeated drying is not allowed, otherwise the coating will be easy to crack and peel off). Pay attention to oil and other dirt on the coating of the welding rod, so as to avoid adding carbon content in the weld and affecting the quality of the welding parts.

　　8. When stainless steel pipe fitting tee is welded, carbides are precipitated by repeated heating, which reduces the corrosion resistance and mechanical function.