Langfang DingYang

Blanking and Defects of National Standard Stainless Steel Flange

fittingflange | 30 January, 2019 09:34

Stainless steel flange is a kind of flange, which is widely used and popularized in the mechanical industry, and has been praised and favored by users. Rolled flange is widely used, and its scope of use is determined according to different characteristics. It is mostly used in mild medium conditions, such as low-pressure non-purified compressed air and low-pressure circulating water. Its advantage is that the price is relatively cheap. Rolled flange is suitable for nominal pressure not more than 2. 5 MPa steel pipe connection, the sealing surface of rolled flange can be made into smooth type, concave-convex type and mortise-groove type. Smooth rolled flange is widely used. The other two kinds of rolled flange are also common in use. The rolled flange includes many types and models. The butt-welded steel flange is used for butt welding of flange and tube, mainly in welding technology, and has good performance. Its structure is reasonable, its strength and stiffness are large. It has high temperature, high pressure, repeated bending and temperature fluctuation. Its sealing performance is reliable. The rolled flange with nominal pressure of 0.25-2.5 MPa adopts concave-convex sealing surface. The processing of stainless steel flange needs to know and pay attention to some problems: 1. Weld defect: The weld defect of stainless steel flange is serious. If manual mechanical grinding is used to remedy it, the grinding trace will cause uneven surface, which will affect the beauty. 2. Non-uniform passivation of grinding and polishing: After manual grinding and polishing, acid pickling and passivation treatment is carried out. It is difficult to achieve uniform and uniform treatment effect for large workpieces, and the ideal uniform surface can not be obtained. There are also its shortcomings, such as the cost of working hours and accessories. 3. Scratches are difficult to remove: integral pickling and passivation, chemical or electrochemical corrosion will occur in the presence of corrosive media, and impurities such as carbon steel and splash adhering to stainless steel surface due to scratches and welding splash can not be removed. So how to solve the problem of stainless steel flange processing? 1. Choose blanking, after completion, enter the next process, different stainless steel workpieces according to the processing requirements into the corresponding process; 2. When bending, first of all, according to the size of the drawing, the thickness of stainless 304 seamless steel pipe should determine the tool and groove used in bending. Avoiding the deformation caused by the collision between the product and the tool is the key to the selection of the upper die (in the same product, different types of upper die may be used), and the selection of the lower die should be determined according to the thickness of the plate. 3. In order to solder firmly, punching bumps on the workpiece to be soldered can make bumps contact with the plate uniformly before electrified welding, so as to ensure the consistency of heating at all points. At the same time, the welding position can be determined. Welding needs to be done. It is necessary to adjust the pre-pressing time, the holding time, the holding time and the resting time to ensure that the workpiece can solder firmly by spot welding. In the process of using stainless steel flange, leakage occurs because of improper connection of stainless steel flange or long service life. Users need not panic when this happens. First, look at the leakage site. It is impossible to inject sealant through the gap to eliminate leakage at the leakage site because of the minimum gap. Sealing construction method is based on the site survey of the leakage site to achieve limited sealing. Fixed fixture method is used to contain leaking points to form sealing chamber and inject sealant to eliminate leaking. Fixtures on one side are customized. Fixtures should satisfy the leaking point. In order to prevent potential leaking of valve body and carbon steel flange clearance due to pressure, annular cavity is installed at the joint of fixture and flange outer edge of valve body. Fixtures with different diameter stainless steel flange tend to be smaller in the process of injecting agent. The displacement occurs on the side of radial flange, so the restriction measure of tooth contact clamping is adopted. After solidification of the sealant during operation, after observation of the effect, local reinjection and compression are carried out to prevent stress relaxation, and then the injection hole is sealed.


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