quality Stainless Steel Seamless Pipe & Seamless Stainless Steel Tubing manufacturer

Stainless steel flat welded flange side accessories are customized. The fixture must first reach the leak point. The main point is to create a closed cavity between the stainless steel flange of the valve body and the pipe joint. To prevent leakage between the valve body and the stainless steel flange due to pressure retention, a ring cavity is provided where the outer edge of the clamp and the stainless steel flange of the valve body overlap. The tooth contact clamp is used as a limiting device because the clamp on the small diameter stainless steel flange is easily moved to the small diameter stainless steel flange during the injection process. After the sealant has hardened during operation, check for stress relaxation and then perform a local re-injection to close the injection port.   Stainless steel flat welding flange installation procedure   1, welding current should not be too large, about 20% smaller than carbon steel electrode, arc can not be too long, interlayer cooling can not prevent heating flange cover corrosion corrosion must be fast.   2, the electrode must be dried before use. Perovskite type should be dried at 150°C for 1 hour, low hydrogen type should be dried at 200-250°C for 1 hour (do not repeat drying more than once. Do not increase the welding, the carbon content of the welding is to prevent the electrode coating from adhering to the oil and other dirt, so as not to affect the quality of the parts.   3. When welding stainless steel flange fittings, carbide precipitation and mechanical properties will occur due to repeated heating and corrosion resistance.   4. After welding, the flange of the hardenable American standard chromium stainless steel flange fittings is larger and easier to crack. Similar types of chrome-stainless steel electrodes (G202, when using G207) must be preheated to 300°C or higher after welding and gradually cooled to about 700°C after welding. If heat treatment of the weld is not possible, the rod (A107, A207) must be used for welding of stainless steel flanges.   5, stainless steel flange, appropriate amount of stable elements Ti, Nb, Mo, etc., to improve corrosion resistance and weldability, weldability is better than chromium stainless steel flange, when using the same type of chromium stainless steel flange electrode (G302, G307), preheat it to 200°C or higher, and tempered to about 800°C after welding. If not, it needs to be used.   6, stainless steel flange electrode (A107, A207), stainless steel flange fittings, welding flange electrode with excellent corrosion resistance and oxidation resistance is widely used in the manufacture of chemicals, fertilizers, petroleum, medical machinery.

There are thousands of varieties of steel used in various industries. Each steel has a different trade name due to different properties, chemical composition or alloy type and content. Although fracture toughness values greatly facilitate the selection of each steel, these parameters are difficult to apply to all steels. The main reasons are:   1. Because a certain amount of some or more alloying elements need to be added in the smelting of steel, different microstructure can be obtained after simple heat treatment, thus changing the original properties of steel; 2. Because the defects generated in the process of steelmaking and pouring, especially concentrated defects (such as pores, inclusions, etc.) are extremely sensitive during rolling, and different changes occur between different furnace times of the same chemical composition steel, and even in different parts of the same billet, thus affecting the quality of the steel. Because the toughness of steel mainly depends on the microstructure and the dispersion of defects (strictly prevent concentrated defects), rather than the chemical composition. Therefore, toughness will change greatly after heat treatment. In order to deeply explore the properties of steel and the causes of fracture, it is also necessary to master the relationship between physical metallurgy and microstructure and steel toughness.   The influence of processing technology   It is known from practice that the impact performance of water-quenched steel is better than that of annealed or normalized steel, because the rapid cooling prevents the formation of cementite at grain boundaries and promotes the finer of ferrite grains. Many steels are sold in the hot rolled state, and rolling conditions have a great influence on impact properties. The lower final rolling temperature will reduce the impact transition temperature, increase the cooling rate and promote the ferrite grain to become finer, thus improving the toughness of the steel. Because the cooling rate of thick plate is slower than that of thin plate, the ferrite grain is thicker than that of thin plate. Therefore, under the same heat treatment conditions, thick plates are more brittle than thin plates. Therefore, normalizing treatment is commonly used after hot rolling to improve the properties of steel plates. Hot rolling can also produce anisotropic steels and directional ductile steels with various mixed structures, pearlite bands and inclusion grain boundaries in the same rolling direction. The pearlite band and elongated inclusions are coarse dispersed into scales, which have great influence on the notch toughness at low temperature in Charpy transition temperature range.   The impact of carbon content in 0.3% ~ 0.8%   The carbon content of hypoeutectoid steel is 0.3% ~ 0.8%, and the proeutectoid ferrite is a continuous phase and first forms at the austenitic grain boundary. Pearlite is formed in austenite grains and accounts for 35% ~ *** of the microstructure. In addition, a variety of aggregation structures are formed within each austenite grain, making pearlite polycrystalline. Because the pearlite strength is higher than the pre-eutectoid ferrite, the flow of ferrite is limited, so that the yield strength and strain hardening rate of steel increase with the increase of the carbon content of pearlite. The limiting effect is enhanced with the increase of the number of hardened blocks and the refinement of the preeutectoid grain size of pearlite. When there is a large amount of pearlite in the steel, micro-cleavage cracks can be formed at low temperatures and/or high strain rates during deformation. Although there are some internal aggregate tissue sections, the fracture channel is initially along the cleavage plane. Therefore, there are some preferred orientations in the ferrite grains between the ferrite plates and in the adjacent aggregation structures.   Stainless steel fracture   Stainless steel is mainly composed of iron-chromium, iron-chromium-nickel alloys and other elements that improve mechanical properties and corrosion resistance. Stainless steel corrosion resistance is due to the formation of chromium oxide on the metal surface to prevent further oxidation - an impermeable layer. Therefore, stainless steel in an oxidizing atmosphere can prevent corrosion and strengthen the chromium oxide layer. However, in reducing atmosphere, the chromium oxide layer is damaged. The corrosion resistance increases with the increase of chromium and nickel content. Nickel can improve the passivation of iron. The addition of carbon is to improve the mechanical properties and ensure the stability of austenitic stainless steel properties. In general, stainless steel is classified by microstructures. Martensitic stainless steel It is an iron-chromium alloy that can be austenitized and post-heat treated to produce martensite. Typically 12% chromium and 0.15% carbon. Ferritic stainless steel. Chromium content about 14% ~ 18%, carbon 0.12%. Because chromium is a stabilizer of ferrite, the austenitic phase is completely suppressed by more than 13% chromium and is therefore a complete ferrite phase. Austenitic stainless steel. Nickel is a strong stabilizer of austenite, so at room temperature, below room temperature or high temperature, nickel content of 8%, chromium content of 18% (type 300) can make the austenite phase very stable. Austenitic stainless steels are similar to ferritic forms and cannot be hardened by martensitic transformation. The characteristics of ferritic and martensitic stainless steels, such as grain size, are similar to those of other ferritic and martensitic steels of the same class.

1, before installation, be sure to carefully check the various standards of stainless steel elbow, check whether the diameter meets the requirements of use, eliminate the defects caused by the transportation process, and remove the dirt of stainless steel elbow, and prepare for installation.   2, when installing, the stainless steel elbow can be directly installed on the pipe according to the connection method, and installed according to the position used. Under normal circumstances, it can be installed in any position of the pipeline, but it needs to be easy to operate maintenance, pay attention to the media flow of the stainless steel elbow should be upstream below the longitudinal valve disc, and the stainless steel elbow can only be installed horizontally. Stainless steel elbow should pay attention to sealing when installing to prevent leakage and affect the normal operation of the pipeline.   3, stainless steel elbow valve packing gland bolts should be evenly tightened, should not be pressed into a distorted state, so as not to hurt hinder the movement of the valve stem or cause leakage.   4, stainless steel elbow ball valve, globe valve, gate valve when used, only fully open or fully closed, not allowed to adjust the flow, so as to avoid the sealing surface erosion, accelerated wear. The gate valve and the upper thread stop valve have reverse sealing devices, and the hand wheel is turned to the upper position to tighten, which can prevent the medium from leaking from the packing place.