Thick-walled seamless steel pipe is as the best choice for liquid delivery But over time, the probability of damage to the pipe is also high. This time, the role of thick-walled seamless steel pipe appeared. Thick-walled seamless steel pipe is now used to transport liquids, the main pipeline, its strength is higher than the average steel pipe, corrosion resistance is also stronger, the use of life increased by more than tenfold.    In addition to thick-walled seamless steel pipe as the best choice for liquid delivery pipe, or the production of the car above the main shaft material. After all, the strength of thick-walled seamless steel pipe is very high, the production of the shaft will not easily deformed, fully able to ensure traffic safety. This shows that thick-walled seamless steel pipe to our life to help, but also very large. But over time, the probability of damage to the pipe is also high. This time, the role of thick-walled seamless steel pipe appeared. Thick-walled seamless steel pipe is now used to transport liquids, the main pipeline, its strength is higher than the average steel pipe, corrosion resistance is also stronger, the use of life increased by more than tenfold.    In addition to thick-walled seamless steel pipe as the best choice for liquid delivery pipe, or the production of the car above the main shaft material. After all, the strength of thick-walled seamless steel pipe is very high, the production of the shaft will not easily deformed, fully able to ensure traffic safety. This shows that thick-walled seamless steel pipe to our life to help, but also very large.

Resistance welding machine , the efficiency of the TIG welding than traditional 3 to 5 times. After often due to lack of penetration of the root and crater and other pit defects instead of using TIG welding end MIG welding filling and capping process, although the improved welding process basically solves the root of the problem of incomplete penetration, reduces the welding efficiency, increased investment in equipment while also complicating operational procedures. Recently, the pot, pot imported from abroad hot wire TIG automatic pipe machine. The principle of hot wire TIG welding is that the filler wire is supplied by a separate constant voltage AC power supply before it is fed into the weld puddle.  Resistance heating to 650 ~ 800 ℃ high temperature, which greatly accelerated the wire melting rate, the deposition rate close to the same diameter MTG welding deposition rate. In addition, the TIG method of good back cover features to ensure the back cover of the weld quality, therefore, hot wire TIG welding is the preferred choice of a small diameter wall thickness butt welding method. However, this should not be a complete denial of the feasibility of pulsed MIG welding in the application of small diameter wall thickness pipe joints. In a large number of experiments, it has been found that in the MIG welded butt joints of thick-walled tubes, more than 90% of the root end penetration is located in the super-arc section, and the crater droop causes overheating due to the metal heat accumulation in the molten pool during continuous multi-layer welding. If the welding power arc power for precise control, you can completely eliminate the formation of the above defects. However, due to the introduction of the MIG welding machine automatic welding machine original wife of the thyristor pulse power supply, can not achieve the arc power of program control, such as switching to the most advanced all-digital control of inverter pulse welding power supply or waveform control pulse welding power supply (computer software control small), you can easily according to the welding process requirements, the power of the welding arc for precise control to ensure the welding quality joints.

The impact of high-frequency welding on the quality of steel pipe, welding technology and technical parameters of the control, the induction coil and the placement of the resistance of the orientation of the weld quality of steel pipe welding, the following four aspects about.   1) Weld seam weld control of steel into the welded pipe unit by the forming roll, the guide roller orientation, the formation of a circular gap with a hollow tube, adjust the amount of kneading the kneading roll, making the weld gap control in 1 -3mm, and keep the two ends of the weld flush. Weld gap control too large, will make the welding seam is not welded or cracking bad; weld gap control too small, because the heat is too large, the formation of the weld burning, molten metal splash, affecting the welding quality of the weld.   2) High-frequency induction coil orientation control loop should be placed in the same base line with the steel tube, induction coil front end from the base line of the kneading roll line spacing, without prejudice to the premise of kneading roll should be regarded as the standard steel pipe as close as possible. If the induction ring away from the kneading roll far, the effective heating time longer, wide heat affected zone, making the strength of welded steel pipe decreased or incomplete penetration; the other hand induction ring easily burned kneading roll.   3) Impedance azimuth regulator is a or a group of dedicated welding rod bar, the cross-sectional area of the resistor should not be less than 70% of the cross-sectional area of the inner diameter of the pipe, its role is to make the induction coil, the weld bead margin and magnetic rod form an electromagnetic induction loop, the proximity effect occurs, the eddy current heat concentrated in the vicinity of the weld bead margins, so that the edge of the tube heated to the welding temperature. Impedance should be placed in the V-zone heating section, and the front end of the base roll in the direction of the roller so that the base line and the tube base line common. If the orientation of the impeller is not good, it will affect the welding speed and welding quality of the welded pipe, causing the crack of the steel pipe.   4) Technical parameters of high-frequency welding - Input heat control high-frequency power input to the pipe weld heat is called the input heat.

Industrial production of large straight seam welded pipe by forming different ways can be divided into the following categories. 1, UOE process The so-called "UOE" process is the first U-shaped steel plate, and then by O forming and expanding, it with three hydroformed to open the tube, and then sent to the welding process. The steel plate is firstly longitudinally edged and chamfered on both sides, and positioned and soldered on the four fillets, and then sent to the crimping machine to progressively press the two sides into a curved shape along the longitudinal direction at first, and then to the hydraulic press flat steel plate pressed into U-shaped, and then transported to O forming hydraulic press, pressed by the upper and lower semicircular die into an open tube. The pressing process is carried out in a precise hydraulic control, giving the open tube a consistent tolerance of tolerance. UOE unit maximum production capacity, product quality, is the world's production of high-precision pipeline steel pipe lsaw pipe unit. 2, RBE (three roll bending plate) process Similarly, the edge of the board is also trimmed and chamfered on both sides in the longitudinal direction first, then the flat steel plate is repeatedly rolled into a circular open pipe body on a three-roll plate bending machine, the pipe body enters a plate edge roller press, rolling the curvature and diameter match. This molding method limits the thickness of the forming tube and the possibility of producing small diameter and thick walled tubes. 3, JCOE (compression molding) process The prepared steel plate is transported to the molding machine, and the operating plate is used to move the steel plate to a pressing station, wherein the steel plate is pressed into the pipe body through a series of steps by an arc-shaped die pressing head. The hydraulic press is operated by two manipulators, which are first pressed to form a semicircle, that is, "J" shape, and the second manipulator transforms the steel plate to form the other half of the bend. The thickness of the stamper affects the roundness of the open tubular body and the thickness is preferably kept to a minimum. Edge rolling and three-roll process is similar. 4, C pressure molding process The C-pressure forming process was first used by Pont-A-Mousson SA in France and is an effective method for producing large longitudinal welded pipes, especially for thick-walled pipe. Molding depends on high control accuracy and large pressure. After preloading of the plate by the roller bending machine, the plate was fed to the C pressure molding machine. Also, two operators were involved in forming the half of the plate on the first C press and then the other half on the other press, that is the first pressure into a "C" shape, and then pressed into "O" shape, so that the formation of an open circular tube. Both the tool and the platen hydraulic pad and stable suppression of small arc, while ensuring the length of the neat. 5, CFE (roll forming) process Roll forming a full-roll molding and semi-roll forming of the points. The so-called semi-roll forming is only the general roll forming machine drive roller frame (that is, flat roller frame) between the idler roll row of small rollers instead to improve the molding conditions. Small roller can adjust the position for a range of pipe size, do not have to change. The whole row of roller molding is in addition to leaving a general roll machine in the first drive roller rack, the other rack all on behalf of a small row of rollers, small roller, especially outside the small roller, applicable to all Steel pipe, do not have to be replaced, so this method is beneficial to increase productivity.

Straight seam pipe is formed by the surface layer of ultra-thin and very solid and stable chromium-rich oxide film (protective film), to prevent the continued infiltration of oxygen atoms, continue oxidation, and corrosion resistance. Once for some reason, the film was continuously damaged, the air or liquid oxygen atoms will continue to infiltrate or continuous separation of iron atoms in the metal, the formation of loose iron oxide, the metal surface will also continue to rust. This surface film is damaged in many forms, more common in everyday life are the following:   1. Straight seam pipe surface deposit with deposits of other metal elements of dust or heterogeneous metal particles in the humid air, the condensate between the attachment and stainless steel, the two connected into a micro-battery, triggering the electricity Chemical reaction, protective film damaged, called electrochemical corrosion.   2. Straight seam pipe surface adhesion of organic juice (such as vegetables, noodles soup, sputum, etc.), in the case of water oxygen, organic acids, organic acids for a long time on the metal surface corrosion.   3. Straight seam steel surface adhesion with acid, alkali, salt substances (such as the renovation of the wall of the alkali water, lime splashing), causing local corrosion.   4. In polluted air (such as a large amount of sulfide, carbon dioxide, nitrogen oxides in the atmosphere), the case of condensate, the formation of sulfuric acid, nitric acid, acetic acid point, causing chemical corrosion.