Users should pay attention to the following matters in the use of flat welding flange products:
- 1. In order to prevent the eye corrosion caused by the heating of the flat welding flange cover, the welding current should not be too large, less than 20% of the carbon steel electrode, the arc should not be too long, and the interlayer should be cooled quickly, and the narrow weld bead is preferred.
- 2. The welding rod shall be kept dry during use. The titanium calcium type shall be kept dry at 150 ℃ for 1 hour, and the low a hydrogen type shall be kept dry at 200-250 ℃ for 1 hour to prevent oil and other dirt on the electrode coating, so as to avoid increasing the carbon content in the weld and affecting the quality of the weldment.
- 3. During the welding of flat welding flange pipe fittings, carbides are precipitated due to repeated heating, which reduces the corrosion resistance and mechanical properties of products.
- 4. Chrome flat welding flange pipe fittings have large hardenability American standard flange after welding, which is easy to produce cracks. If the same type of chromium stainless steel electrodes (G202, G207) are used for welding, preheating above 300 ℃ and slow cooling treatment at about 700 ℃ after welding must be carried out. If the weldment cannot be subject to post weld heat treatment, welding rods (A107, A207) for flat welding flange pipe fittings shall be selected.
- 5. For the flat welding flange, an appropriate amount of stability elements Ti, Nb, Mo, etc. are added to improve the corrosion resistance and weldability. The weldability is better than that of the chromium flat welding flange. When the same type of chromium flat welding flange electrode (G302, G307) is used, it shall be preheated at more than 200 ℃ and tempered at about 800 ℃ after welding. If the weldment cannot be heat treated, the welding rod (A107, A207) for flat welding flange shall be selected.
Main functions of flat welding flange:
- 1. Connect the pipeline and keep the pipeline sealing performance;
- 2. Facilitate the replacement of a certain section of pipeline;
- 3. Easy to disassemble and check the pipeline;
- 4. Facilitate the sealing of a certain section of pipeline.