1.Corrosive environment. In the tubes of the tubular heat exchanger, the main medium is liquid titanium tetrachloride, and it also contains chlorides such as ferric chloride and sodium chloride. Due to the absence of purging and drainage devices in the tubular heat exchanger, air and water droplets enter during long-term shutdown, causing the hydrolysis of titanium tetrachloride in the pipeline and clogging it. Chloride ions reduce the corrosion resistance of the material, accelerating corrosion.

　　2.Material. The tube material of the tubular heat exchanger is1Cr18Ni9TiStress corrosion is prone to occur in a chloride ion environment, which is generally transgranular fracture.

　　3.Residual stress. The residual stress of the elbow has not been eliminated. The stress comes from the residual stress generated during the manufacturing process and the working stress caused by the load. Under the influence of internal pressure, thermal stress, welding residual stress, etc., the elbow of the tubular heat exchanger has the condition of horizontal tensile stress.

　　Solution

　　1.Maintenance management. To ensure the long-term operation of the tubular heat exchanger, it is necessary to strictly enforce the rules and regulations of the heat exchanger, review the existing defects, promptly grasp the development of defects during operation, and take appropriate measures to reduce the corrosion of the equipment.

　　2.Strictly follow the operating procedures. The process operation and process conditions have a significant impact on the corrosion of austenitic stainless steel elbows. Therefore, strictly control the medium composition, flow rate, medium temperature, pressure,pHAdd corrosion inhibitors within the allowable range of process conditions based on the values and other process indicators.

　　3.Stress control: Through stabilization treatment after solution treatment, some stress can be eliminated and the crack resistance of the material can be improved. However, when considering this method of eliminating local stress, various problems that may be caused by sensitization should be well weighed.

　　4.Select materials resistant to stress corrosion. In recent years, a variety of stainless steels resistant to stress corrosion have been developed: high-purity austenitic chromium-nickel steel, high-silicon austenitic chromium-nickel steel, high-chromium iron steel and ferritic-austenitic duplex steel. Among them, ferritic-austenitic duplex steel has better resistance to stress corrosion.

　　The main difference between stainless steel elbows and carbon steel elbows lies in their materials. The chemical components they contain can prevent the surface of the elbows from rusting and being corroded for a long time.


　　How to do a good job in the maintenance and repair of stainless steel elbows

　　1.Stainless steel elbows that have been stored for a long time should be inspected on time. The exposed surfaces should be kept clean, free of dirt and neatly stored in a well-ventilated and dry indoor place. It is strictly prohibited to stack or store outdoors. Always keep the stainless steel elbows dry and well-ventilated, maintain the cleanliness and tidiness of the equipment, and store them in accordance with the correct storage methods.

　　2.When installing, stainless steel elbows can be directly installed on the pipeline according to the connection method, and stainless steel elbows can also be installed according to the usage position. Generally speaking, it can be installed at any position on the pipeline, but it needs to be convenient for inspection during operation. Note that the medium flow direction of the stainless steel elbow should be from the bottom of the longitudinal valve disc to the top. The stainless steel elbow can only be installed horizontally. When installing the stainless steel elbow, pay attention to sealing to prevent leakage and avoid affecting the normal operation of the pipeline.

　　3.Stainless steel elbow ball valves, globe valves and gate valves can only be opened or closed and are not allowed to adjust the flow rate to avoid corroding the sealing surface and accelerating wear. The gate valve and the upper threaded stop valve are equipped with inverted sealing devices, and the top position of the handwheel is fastened to prevent the medium from leaking from the filling point.

　　　　Foshan Weilihuang Trading Co., Ltd. is a leading manufacturer specializing in the production and sales of international and domestic stainless steel hardware accessories and its own brands. The company is located at Tianjinli Hardware Accessories Center, Lanshi 2nd Road, Chancheng District, Foshan City, Guangdong Province8seat10-12The number (i.e., the main entrance of the market) has an abundant supply of goods, a complete range of varieties, wide coverage, favorable prices, and stable and superior quality!

　　　　The company uses high-quality stainless steel and exquisite craftsmanship to ensure there are no weld marks at the interfaces. Its products feature novel designs, elegant craftsmanship, and long-lasting durability. The company has always adhered to the principle of quality first and reputation first. It is equipped with mature production facilities and has strong technical strength, thus ensuring the quality of its products. The company is willing to make unremitting efforts to join hands with our customers to create a win-win situation and provide high-quality products for our partners.