SSAW Pipe

What is welding slag inclusion? Welded pipe slag inclusions are slag that remains inside the weld. Welding slag inclusions are generally divided into two categories: The first category is metal slag inclusions. The second category is non-metallic slag, which refers to the slag remaining in the weld after welding, including electrode coating or flux, sulfide, oxide and nitride. According to its formation, it can be divided into point-like slag inclusions, linear slag inclusions, chain-like slag inclusions and dense slag inclusions. Slag inclusions will reduce the plasticity and toughness of steel pipe welds, and slag inclusions with sharp corners will cause stress concentration at the tip, and the tip will develop into a crack source, especially in welds with a large tendency to air quenching. Under the action of stress on the steel pipe, cracks will first appear at the slag inclusions in the weld and develop along the way, resulting in a decrease in strength and cracking of the weld. T...

Welded steel pipes are widely used in the structural parts of bicycles, motorcycles, tractors, automobiles and large buses. The pipe has a large forging coefficient, strong bending and torsion resistance, smooth surface and light weight. Variable cross-section tubes are used to make collector poles on trolleybuses, because this high-strength welded steel tube has good toughness and elasticity. Welded steel pipes are widely used in instruments, telecommunication equipment and medical equipment to manufacture brackets, guide rails, and frames of boxes and cabinets, so that they have the characteristics of light weight, beautiful appearance, novel style, and easy handling and portability. Surgical operations directly use the plum-blossom needle high-strength welded steel pipe as the bone-setting material. The waveguide for UHF radio communication is also made of special high-strength welded steel pipe with precise dimensions. On various thermal equipment, mechanical equipment or radio rec...

 Seamless steel pipe is the best choice when it comes to boiler tube. Welded steel pipe has a weld seam, so if the working temperature is with high pressure or high pressure, welded steel pipe may not your best choise, because weld seam may can’t endure working temperature or pressure to be so high. Weld seam may crack under high pressure or high pressure. Product range of seamless boiler tube is from 10.3mm to 914.4mm. Most common seen standard and steel grade are as below: DIN 17175 EN10216-1, EN10216-2, EN10028-2. JIS G 3461, JIS G 3462, JIS G 3456, JIS G 3458. ASME SA-106, ASME SA-209, ASME SA-210M, ASME SA-213M, ASME SA-335M, ASME SA-192M, ASME SA-333. http://www.tjxysteel.com/news/A-guide-to-Seamless-Boiler-Tube-270.html

 10th,Jan,2018, Because of need for equipment, Mr Mehdi from Europe was looking for UN Standard welded steel pipes in small quantity.Because it’s the first time for Mr Mehdi to import, after consulting with other companies, they sent the first enquiry to Tianjin Xinyue Steel Group’s website(www.xysteelpipe.com). According to client’s saying, part of the mill refused to quote because of the small quantity and high technics. After receiving the quotation, xinyue steel confirmed the drawing asap and deal with it immediately. All orders, no matter it’s big or small, are very important to us. After negotiating with the clients, after three months, because of the high technics and serious diameter tolenrance, Mr Mehdi finally placed an trial order with one container to us. After one month and an half, the goods finally arrived the destination.However, because of the transportation problem and the thin wall thickness, one or two pipes are twisted. After knowing the problem, we actively co...

　　API early in 1926 released by the American Petroleum Institute (API) API-5L standard, initially including three steel grade A25, A, B, and later released several times. Prior to 2000, the worldwide use X70, about 40%, X65, X60 are in the 30%, a considerable number of small-caliber product oil pipeline selection of X52 steel grade, mostly for resistance welding straight pipe ( ERW steel pipe ). 　　China is currently used in the Petroleum Pipeline tube spiral welded pipe (SSAW), LSAW pipe (LSAW), electric resistance welded pipe (ERW). Diameter less than 152mm selection of seamless steel tubes. Of the late 1960s to the 1970s, spiral pipe plant rapid development of crude oil pipelines almost all spiral welded steel pipe, "West-East pipeline region selection spiral welded steel pipe. The spiral welded steel pipe of the disadvantage is the internal stress is large, the dimensional accuracy is poor, the probability of generation of defects. According to expert analysis, should adopt t...

　　Spiral steel pipe is also called a spiral steel pipe, which is generally referred to as a spiral steel pipe with a diameter of more than 1 meter. Steel pipes are subject to water pressure, tortuosity and pressure. Flat and other experiments have certain requirements on the surface quality. The general delivery length is 12 meters, often requiring fixed delivery. A metal material with a yielding phenomenon, the stress of the sample is not added (persistently stable) during the stretching process, and the stress at the time of elongation is continued, which is called the yield point. 　　If the force attack declines, the upper and lower yield points should be distinguished. The unit of the yield point is N/mm2 (MPa). The sample is connected during the stretching process. The maximum force (Fb), the stress (σ) obtained from the original cross-sectional area (So) of the sample, is called the tensile strength (σb), and the unit is N/mm2 (MPa). It shows the maximum ability of metal materia...

　　The technology of welded steel pipe is continuous online production. So the thicker the wall thickness is, the greater the investment in the unit and welding equipment is, and welded steel pipe will have less economical efficiency and practical applicability. The wall thickness is thinner, its input-output ratio will be decreased accordingly. The process of the product determines its advantages and disadvantages. In general, the welded steel pipe with high precision, uniform wall thickness, high brightness of tube inside and outside (surface grade of steel plate determines the surface brightness of steel pipe), can be fixed length wilfully. Therefore, welded steel pipe reflects its economy and aesthetics in the high-precision, low-pressure fluid applications. 　　The production process of welded steel pipe is simple, the production efficiency is high, the cost is low, and develops rapidly. The strength of the spiral welded pipe is generally higher than that of the straight seam weld...

　　1) The seamless pipe is a long strip of steel with a hollow section and no joints around it. It is a steel pipe without seams, hot rolling or cold drawing process. Seamless steel pipe characteristic is that its pressure endurance is fairly good. 　　2) Welded steel pipe, also called welded pipe, is a steel pipe made by welding a steel plate or a strip steel after being crimped. Can be divided into straight seam welding and spiral seam welded steel pipe. More than an inappropriate example, you roll rectangular white paper into a tube, and then the edge is welded is a straight seam welded pipe, if you roll up and then welded, it is a spiral seam welded steel pipe. The welded steel pipe has a simple production process, high production efficiency, many varieties and specifications, the strength is generally lower than that of the seamless steel pipe, more than 800mm are welded steel pipes, which are welded by steel plates, which is determined by the current state of the art. 　　3) Featu...

　　Oxyfuel and plasma cutting play an important role during the production process of making welded steel pipe like ERW steel pipe . And forgetting to grind the joint after oxyfuel or plasma cutting would be an common mistake for a new welder. 　　Today, we can make it alone to make an essay to tell all of us who need to choose steel pipes or producing tubes. Adding a layer of oxide to the cut edge during the oxyfuel and plasma cutting processes would be the necessary step for steel pipe. And here are the notices: 　　First of all, the oxide layer has to be removed prior to welding due to the higher melting point of oxide than base metal. 　　What’s more, the oxides can also remain in the weld and cause porosity, inclusions, lack of fusion and other defects. 　　In addition, welders have to keep in mind to grind the joint down to the parent material prior to welding, as well as grind the inside and outside diameters of the pipe to remove these oxides and other potential contaminants.

　　Mechanical tests would be an important step for final steel pipe product. What’s the points we should pay attention to for this step when we make tests for seamless steel pipe or other welded steel pipe . 　　First of all, we should familiar with the test types, such as transverse or longitudinal tension test, flattening test, hardness test, or bend test. 　　Then, for different materials, we should use different methods to test too. For example, if the material heat treated in a batch-type furnace, tests shall be made on 5% of the pipe from each treated lot. For small lots, at least one pipe shall be tested. 　　What’s more, for material heat treated by the continuous process, tests shall be made on a sufficient number of pipe to constitute 5% of the lot, but in no case less than 2 pipe.

　　Forged: forging hammer use reciprocating impact force or press pressure so we need to change the blank shape and size of a pressure processing method. 　　Extrusion: steel metal is placed in closed extrusion Jane, put pressure on one end of the metal from the die orifice to obtain a predetermined extrusion has the same shape and size of the finished product processing method used for the production of non-ferrous metal steel . 　　Rolling: the metal blank of steel through a pair of gap (of various shapes) rotating rolls, due to compression of the material cross-section roll is reduced, the length of the increased pressure processing method. 　　Pullout: rolled metal blank (type tube, products, etc.) through a die orifice dial into reduced cross-section pulling length increased processing method is used mostly cold.

　　The first mode of production: the tube (plate, belt) molded directly welded into the pipe, the main steps of the strip forming, welding, sizing. Features: less production processes, engineering process is simple, short production cycle, product accuracy is slightly lower. 　　The second mode of production: the tube (plate, belt) first formed directly welded into a certain size pipe, then through the cold-drawn or cold-rolled into a finished tube, known as DOM welded steel pipe . The main processes are forming, welding, sizing, cold-rolled or cold-drawn (with mandrel or without mandrel), or continuous cold drawn (ie welding; joint production of cold drawn wire). Features: decentralized production processes, process and production cycle is long, large area, good dimensional accuracy, smooth inner and outer surfaces, mechanical properties and microstructure good state. 　　The third mode of production: the tube (plate, belt) first formed directly welded into the pipe after a certain siz...

　　Welded steel pipe is a hot-rolled coil after molding machine, the use of high-frequency current skin effect and proximity effect, so that the edge of the tube is heated to melt under the action of squeezing rollers pressure welding to achieve production. 　　High frequency resistance welding method used in pipe production of the 1950s. Over the past decade, the production technologies are maturing, continuously improve product quality. 　　First, ERW steel pipe used in the production of raw material quality has been significantly improved, the steel component design of the low C, low P, S, micro-alloying; smelting process smelting, ladle refining, vacuum degassing, continuous casting and other new using technology; ERW pipe - ERW rolling process controlled rolling, controlled cooling technology enables the use of medium and large caliber ERW steel pipes hot strip appearance of size, appearance quality, physical and chemical properties greatly improved. On behalf of my hot strip high...

　　There are various kinds of steel pipes both in domestic and international markets for your selection, like the welded steel pipe . The steel pipe can be used as the long-distance oil and gas pipeline actually which can ensure the energy security actually. However, the surface of the stee pipe should be treated with great care to avoid the corrosion. Although the surface can't determine the corrosion totally, it has great influence except the weather condition, enviromental factors, coating type, quality and so forth. Hence, it is of great importance to learn how to coat the steel pipe in a simple but effective way. 　　For example, you are advised to clean it very carefully. In order to remove the grease, oil, dust, lubricants, you are advised to use solvent, emulsion to clean the steel surface actually. However, such cleaning can't help remove the surface rust, oxide, welding flux and so forth. So, you may need a steel wire brush and other tools to polish the steel surface t...

　　In manufacturing and welding aspects 　　Comparatively speaking, longitudinal welded steel pipe has simple manufacturing and welding techniques. As the name shows, longitudinal pipe has a straight welding seam on the pipe surface. Different from the longitudinal pipe, the welding seam of which is vertical to the axial line of the pipe, helical welded pipe is rolled and welded according to certain helical angles. Therefore, helical welded pipe manufacturing, with complicated welding method, is more time-consuming. As for longitudinal welded pipes, to meet the required length of pipelines used in industry projects, short longitudinal pipes always need to be jointed and welded into a long enough pipe. Thus, inevitably, many T-shaped welding seams would appear in this welding process, largely increasing the possibility of welding defects. 　　Besides, T-shaped welding joints incline to cause welding residual stress, which lays potential risk for future fatigue crack. Therefore, though h...

　　There are three common methods for forming welded steel pipes: 　　1. Single radius forming method 　　The single-radius roll forming method has three methods: a circumferential bending forming method, an edge bending forming method, and a center bending forming method. The single radius forming method is: the hole type is composed of a single radius, and the forming machine horizontal roller and vertical roller are alternately arranged, and the strip is formed. From the middle of the horizontal roller and the vertical roller, the flat plate is gradually bent into a circular tube. 　　2. Circular bending forming method 　　The strip is bent and deformed at the same time in the whole width direction, and the bending radius of each frame is gradually reduced; the edge bending forming method starts from the edge of the strip, the bending radius is constant, and the deformation angle is gradually increased to reduce the middle portion of the strip. Width until the steel strip is rounded;...

　　In the production process of welded steel pipe , quality inspection is a very importance of foundation link. In general, pipe manufacturer will use optical microscope to test weld seam. Optical microscope is light waves to deal with visible and near-visible, bunching the beam to irradiate on the object, the imaging falls on the human retina, photosensitive film or other recording system, breaking the limitations of human physiology, the visual extension to The human eye can not tell the microscopic world. It is the most important optical precision instrument used to observe, record and study the fine structure of the object being examined. 　　High-frequency welded steel pipe is using the welding method to effectively connect the metal material. When pipe manufacturers produce high-frequency welded steel pipe (such as ERW steel pipe, LSAW steel pipe, spiral welded pipe), many factors in the welding process directly affect the weld metal and heat affected area of the macrostructure an...

　　When the factories manufacture welded steel pipe , the strip is fed into the welded pipe unit, rolled by the multi-way roll, the strip is gradually rolled up to form the circular tube with the opening gap, the pressing amount of the pressing roller is adjusted so that the gap of the weld is controlled at 1 ~ And make the ends of the weld flush. If the gap is too large, resulting in reduced proximity effect, insufficient eddy current heat, weld intergranular junction failure caused by non-fusion or cracking. If the gap is too small is caused by the adjacent effect increases, welding heat is too large, resulting in weld burns; or weld seam formed a deep pit after squeezing and rolling, which affects the surface quality of the weld. 　　1.The control of welding temperature 　　The welding temperature is mainly affected by the high-frequency eddy current thermal power. According to the correlation formula, the high-frequency eddy current heat is mainly affected by the current frequency, ...

　　Generally speaking, the welded steel pipes are divided into general welded pipe, galvanized welded pipe, oxygen welding tube, metric system welded tube, transformer tube, welding thin wall pipe and spiral welded pipe etc. 　　General welded pipe: General welded pipe adopts Q195A, Q215A and Q235A or mild steel as raw materials. It is used to transfer the low pressure fluid. In addition, the pipes need water pressure, bending and flattening test etc. Usually, it has some certain requirements on the surface quality. The length of delivery is often from 4 to 10mm. The specifications of welded pipe in nominal diameter are different from actual size. Depending on the wall thickness, welded pipe are also divided into common steel pipe and thicken steel pipe. 　　Galvanized welded pipe: In order to enhance the corrosion resistance, the general welded pipe is galvanized zinc as protective layer. Galvanized steel pipe has two types: hot dip galvanized pipe with thicken zinc layer and electric...

　　Welding preheating is the process before high frequency welding or submerged-arc welding process for producing welded steel pipes . When the environment temperature is too low, welding preheating process is quite necessary. Besides, this process is widely applied for the weldments has large thickness, high strength level, hardening tendency, and good thermal conductivity. 　　In general, the welding preheating is applicapable in the welded seam areas or the whole steel pipes. For example, during the ERW Steel Pipes manufacturing process, the welding preheating process will be only applied in the welded seam areas. 　　The purpose of the welding preheating process is to reduce the cooling speed of the welded joints and preheating temperature. Welding preheating can reduce the cooling speed, but it will not influence the high temperature maintaining time. Therefore, in order to decreases the hardening tendency, applying welding preheating process to reduce the cooling rate is significa...