Quality flange manufacturer

    Different flange characteristics and use attention

    Compared with carbon steel, stainless steel has the following characteristics:

     1) High cathode rate, about 5 times that of carbon steel.

    2) Large linear expansion coefficient, 40% larger than carbon steel, and as the temperature rises, the value of the linear expansion coefficient increases accordingly.

    3) Low thermal conductivity, about 1/3 of carbon steel.

    Caution for use:

    1. In order to prevent corrosion between the eyes due to the heating of the flange cover, the welding current should not be too high Larger, about 20% less than carbon steel electrode, the arc should not be too long, the interlayer cools quickly, and the narrow weld bead is better.

    2. Welding rods should be kept dry when used, titanium calcium type should be dried at 150 ℃ for 1 hour, and low a hydrogen type should be dried at 200-250 ℃ for 1 hour (no more Repeat the drying times, otherwise the coating will easily crack and peel) to prevent the coating of the electrode from sticking 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 flange pipe fittings are welded, carbides are precipitated by repeated heating, which reduces corrosion resistance and mechanical properties.

    4. After welding, the hardenability of the chrome flange pipe fittings is larger and the American standard flange 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 treatment at about 700°C after welding must be carried out. If the weldment cannot be subjected to post-weld heat treatment, flange pipe fitting electrodes (A107, A207) should be used.

    5. Flange, in order to improve the corrosion resistance and weldability, appropriate amount of stability elements Ti, Nb, Mo, etc. are added appropriately, and the weldability is better than that of chrome flanges. When using the same type of chromium flange electrode (G302, G307), it should be preheated above 200℃ and tempered at about 800℃ after welding. If the weldment cannot be heat treated, flange pipe welding rods (A107, A207) should be used.

    6. Flange pipe fittings, butt welding flange electrodes have good corrosion resistance and oxidation resistance, and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.

    Flange is a disc-shaped part, the most common in pipeline engineering, flanges are used in pairs and matching flanges on the valve. In pipeline engineering, flanges are mainly used for pipeline connection. In the pipelines that need to be connected, a flange plate is installed for various installations. The low-pressure pipeline can use the wire connection flange, and the welding flange is used for the pressure above 4 kg. A gasket is added between the two flanges and then tightened with bolts. Flanges with different pressures have different thicknesses and use different bolts.

    Flanges are stainless steel flanges, because stainless steel has good corrosion resistance, so it can make structural components permanently maintain the integrity of the engineering design. The flange will not produce corrosion, pitting, rust or wear. The chromium-containing flange also integrates mechanical strength and high extensibility, and is easy to process and manufacture parts, which can satisfy the needs of architects and structural designers. All metals react with oxygen in the atmosphere to form an oxide film on the surface. If holes are formed, paint or oxidation-resistant metal can be used for electroplating to ensure the surface of carbon steel, but, as people know, this kind of protection is only a thin film.

    In pipeline engineering, flange flanges are mainly used to connect pipelines. Pipes that need to be connected, flanges for various installations, low-pressure pipes can use wires connected to the flanges, use more than 4 kg of pressure to weld the flanges, seal the two flanges between the points, and then fasten them with bolts. Different pressure flanges have different thicknesses and use different bolts to connect pumps and valves and pipes. These parts of the equipment are also made into corresponding flange shapes.

    Comparing the physical properties of stainless steel and carbon steel, the density of carbon steel is slightly higher than that of ferritic and martensitic stainless steel, but slightly lower than that of austenitic stainless steel; The resistivity is in increasing order of carbon steel, ferritic, martensitic and austenitic stainless steel; the order of linear expansion coefficient is similar, austenitic stainless steel is the highest and carbon steel is the smallest; carbon steel, ferritic and martensitic stainless steel The austenitic stainless steel is magnetic, and the austenitic stainless steel is non-magnetic. However, it will produce magnetism when it is cold-worked and hardened to form a tensite transformation. Heat treatment can be used to eliminate this martensitic structure and restore its non-magnetism.