What are the precautions for using stainless steel flanges

While stainless steel flanges have unique advantages in terms of material, even the best products require certain precautions to ensure their longevity.

What specific precautions should be taken when using stainless steel flanges?

1. To prevent intergranular corrosion caused by heating the flange cover, the welding current should not be too high, about 20% less than that of carbon steel welding rods. The arc should not be too long, and rapid cooling between layers is recommended, with narrow weld beads.

2. Welding rods should be kept dry before use. Titanium-calcium type rods should be dried at 150℃ for 1 hour, and low-a-hydrogen type rods should be dried at 200-250℃ for 1 hour (do not repeatedly dry them, otherwise the coating will easily crack and peel off). Prevent the welding rod coating from being contaminated with oil and other dirt, as this will increase the carbon content of the weld and affect the quality of the weld.

3. During welding, stainless steel flanges and pipe fittings are subjected to repeated heating, which causes carbide precipitation, reducing corrosion resistance and mechanical properties.

4. Chromium stainless steel flanges and pipe fittings have a higher degree of post-weld hardening, making them prone to cracking. If using the same type of chromium stainless steel welding rods (G202, G207), preheating to above 300℃ and slow cooling to around 700℃ after welding are required. If post-weld heat treatment is not possible, stainless steel flange and pipe fitting welding rods (A107, A207) should be used.

5. Stainless steel flanges, with appropriate additions of stabilizing elements such as Ti, Nb, and Mo 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 to above 200℃ and tempering to around 800℃ after welding are required. If post-weld heat treatment is not possible, stainless steel flange and pipe fitting welding rods (A107, A207) should be used.