304 stainless steel is a universal stainless steel material, and its rust resistance is stronger than that of 200 series stainless steel materials. The high temperature resistance is also relatively good, and the general operating temperature limit is less than 650 °C. 304 stainless steel has excellent corrosion resistance and good resistance to intergranular corrosion. For oxidizing acids, it was found in experiments that 304 stainless steel has strong corrosion resistance in nitric acid with a concentration of ≤65% below the boiling temperature. It also has good corrosion resistance to alkaline solutions and most organic and inorganic acids.

It shows that the leakage of the pipeline is caused by the sensitization treatment during welding and the rapid occurrence of intergranular stress corrosion cracking under the dual action of chloride and sulfide solution. Corresponding protective measures are proposed.

The production of large and small heads is basically based on pressing, but the pressing process will increase the hardness and density of the steel, but if it is not heated, cracks will easily occur.

For the control of the reducing range, under normal circumstances, the first processing range of the size head is within the first grade. For example, the size head of 325-159 needs to be heated several times. The diameter of the tube is pressed to 273. This pressing also needs to be heated. The second diameter reduction is the process of 273 to 219. This time, the tube needs to be heated to the specified temperature and then pressed. Then there is the process of reducing the diameter of 219 to 159. Each time the diameter is reduced, heat treatment is required.

Various materials have their own characteristics such as hardness and tensile strength, so it is determined that the pressing force of each material is also different. The same type of head, different materials, different processing methods and procedures will also be very different, such as It is said that the head of ordinary carbon steel will be formed after 3 times of heat treatment. However, the greater the hardness of the head of the alloy material, the more times of pressing and heating, and the more complicated the forming process.

Yanshan Jintai Pipe Fittings Manufacturing Co., Ltd.