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Steel strip in coil, which has been slit into the required width from wide strip, is shaped by a series of forming rolls into a multiple length shell. The longitudinal edges are continously joined by high frequency resistance/induction welding. Tube and Pipe Manufacturing Processes Steel pipes are made by two different processes. The overall production method for both processes involves three steps. First, raw steel is converted into a more workable form. Next, the pipe is formed on a continuous or semicontinuous production line. Finally, the pipe is cut and modified to meet the customer’s needs. Ingot production 1 Molten steel is made by melting iron ore and coke (a carbon-rich substance that results when coal is heated in the absence of air) in a furnace, then removing most of the carbon by blasting oxygen into the liquid. The molten steel is then poured into large, thick-walled iron molds, where it cools into ingots. 2 In order to form flat products such as plates and sheets, or long products such as bars and rods, ingots are shaped between large rollers under enormous pressure. Producing blooms and slabs 3 To produce a bloom, the ingot is passed through a pair of grooved steel rollers that are stacked. These types of rollers are called “two-high mills.” In some cases, three rollers are used. The rollers are mounted so that their grooves coincide, and they move in opposite directions. This action causes the steel to be squeezed and stretched into thinner, longer pieces. When the rollers are reversed by the human operator, the steel is pulled back through making it thinner and longer. This process is repeated until the steel achieves the desired shape. During this process, machines called manipulators flip the steel so that each side is processed evenly. 4 Ingots may also be rolled into slabs in a process that is similar to the bloom making process. The steel is passed through a pair of stacked rollers which stretch it. However, there are also rollers mounted on the side to control the width of the slabs. When the steel acquires the desired shape, the uneven ends are cut off and the slabs or blooms are cut into shorter pieces. Further processing 5 Blooms are typically processed further before they are made into pipes. Blooms are converted into billets by putting them through more rolling devices which make them longer and more narrow. The billets are cut by devices known as flying shears. These are a pair of synchronized shears that race along with the moving billet and cut it. This allows efficient cuts without stopping the manufacturing process. These billets are stacked and will eventually become seamless pipe. 6 Slabs are also reworked. To make them malleable, they are first heated to 2,200° F (1,204° C). This causes an oxide coating to form on the surface of the slab. This coating is broken off with a scale breaker and high pressure water spray. The slabs are then sent through a series of rollers on a hot mill and made into thin narrow strips of steel called skelp. This mill can be as long as a half mile. As the slabs pass through the rollers, they become thinner and longer. In the course of about three minutes a single slab can be converted from a 6 in (15.2 cm) thick piece of steel to a thin steel ribbon that can be a quarter mile long. 7 After stretching, the steel is pickled. This process involves running it through a series of tanks that contain sulfuric acid to clean the metal. To finish, it is rinsed with cold and hot water, dried and then rolled up on large spools and packaged for transport to a pipe making facility. Pipe making 8 Both skelp and billets are used to make pipes. Skelp is made into welded pipe. It is first placed on an unwinding machine. As the spool of steel is unwound, it is heated. The steel is then passed through a series of grooved rollers. As it passes by, the rollers cause the edges of the skelp to curl together. This forms an unwelded pipe. 9 The steel next passes by welding electrodes. These devices seal the two ends of the pipe together. The welded seam is then passed through a high pressure roller which helps create a tight weld. The pipe is then cut to a desired length and stacked for further processing. Welded steel pipe is a continuous process and depending on the size of the pipe, it can be made as fast as 1,100 ft (335.3 m) per minute. 10 When seamless pipe is needed, square billets are used for production. They are heated and molded to form a cylinder shape, also called a round. The round is then put in a furnace where it is heated white-hot. The heated round is then rolled with great pressure. This high pressure rolling causes the billet to stretch out and a hole to form in the center. Since this hole is irregularly shaped, a bullet shaped piercer point is pushed through the middle of the billet as it is being rolled. After the piercing stage, the pipe may still be of irregular thickness and shape. To correct this it is passed through another series of rolling mills. Final processing 11 After either type of pipe is made, they may be put through a straightening machine. They may also be fitted with joints so two or more pieces of pipe can be connected. The most common type of joint for pipes with smaller diameters is threading—tight grooves that are cut into the end of the pipe. The pipes are also sent through a measuring machine. This information along with other quality control data is automatically stenciled on the pipe. The pipe is then sprayed with a light coating of protective oil. Most pipe is typically treated to prevent it from rusting. This is done by galvanizing it or giving it a coating of zinc. Depending on the use of the pipe, other paints or coatings may be used. SEAMLESS PIPE MANUFACTURING Our seamless pipe manufacturing process involves the following steps: Transformation of raw materials into steel bars (Electric arc furnace, ladle furnace, vacuum degassing and continuous casting processes) Transformation of steel bars into mother pipe, which is manufactured in different types of rolling mills Each product is manufactured in accordance with customer specifications, including heat treatment for more demanding applications. Our pipes are threaded and undergo non-destructive testing before delivery to the customer. We also offer cold-drawing for pipes with the diameter and wall thickness required for use in boilers, superheaters, condensers, heat exchangers, automobile production and several other industrial applications. Our seamless pipe production facilities are located in North and South America, Europe and Asia. WELDED PIPE MANUFACTURING Our manufacturing facilities perform three types of welding processes: Electric Resistance Welding: During ERW, a high frequency electrical current is transmitted to the material by means of copper sliding contacts so that the abutting edges initiate fusion as they come into contact. Longitudinal Submerged Arc Welding: In LSAW, the butt joint of the pipe is welded in at least two phases, one of which is on the inside of the pipe. The welds are made by heating with an electrode arc between the bare metal electrodes. Pressure is not used. Filler metal for the welds is obtained from the electrodes. Spiral Submerged Arc Welding: Spiral SAW allows large diameter pipes to be produced from narrower plates or skelps. During this process, the weld pool is protected against oxidation by a flux produced from the electrode fed separately onto the weld. Our welded pipe production facilities are located in North and South America.

ERW pipe means Electric Resistance Welded Pipes. A plate rolled to become a pipe and welded using Electric Resistance Welding process. Usully for for high diameter. (cheapest process avaiable) Typical ERW pipe (Electrical Resistance welded Pipe) Manufacturing Process Our manufacturing process generally involves the following stages in a step by step procedure. Slitting HR Coils are slitted to pre-determined widths for each and every size of pipes Uncoiling, End Shearing And Welding The slitted coil is uncoiled at the entry of ERW mill and the ends are sheared and welded one after another. This results in a single endless strip. Forming The slitted coils are initially formed into U shape and after that into a cylindrical shape with open edges utilizing a series of forming rolls. Welding In this stage, the open edges are heated to the forging temperature through high-frequency, low-voltage, high current and press welded by forge rolls making perfect and strong but weld without filler materials. De beading In this stage, the weld flash on top and inside (if required) is trimmed out using the carbide tools. Seam Annealing If required, the welding portion and heat affected zone is put to normalizing and then are cooled down in a air cooling bed. Sizing After water quenching, slight reduction is applied to pipes with sizing rolls. This results in producing desired accurate outside diameter. Cutting In cutting stage, the pipes are cut to required lengths by flying cut off disc/saw cutter. End Facing And Bevelling This is usually stage, where the pipes ends are faced and bevelled by the end facer. All these processes are continuous with automatic arrangements. These plain ended tubes further go for processing as per the customer requirements such as galvanizing, threading, black varnishing and more. Galvanizing Galvanizing Line Continuous Hot-Dip galvanizing mill roll out galvanized coils of International quality. These lines are supported with on line tension leveling, trimming lines and skin pass mills, to take care of special requirements of customers in terms of coating mass, width, thickness etc.. Sheet Corrugation Corrugation machine (Sheet-to-Sheet type) capable of profiling Galvanized sheets upto 3 meters length with maximum dimensional accuracy. All these facilities are also supported by a service center, which tailor makes the coils to customer- requirements by slitting & cutting and by delivering sheets/ coils to customer specifications. Electric Resistance Welded (ERW) ->Solid phase butt weld, was produced using resistance heating & high pressure to make the longitudinal weld (ERW), ->Nowadays Most pipe mills now use high frequency induction heating (HFI) for better control and consistency. However, the product is still often referred to as ERW pipe, even though the weld may have been produced by the HFI process. ->The defects that can occur in ERW/HFI pipe are those associated with strip production, such as laminations and defects at the narrow weld line. ->Lack of fusion due to insufficient heat and pressure is the principal defect, although hook cracks can also form due to realignment of non metallic inclusions at the weld interface. Because the weld line is not visible after trimming, and the nature of the solid phase welding process, considerable lengths of weld with poor fusion can be produced if the welding parameters fall outside the set limits. ->In addition, early ERW pipe was subject to pressure reversals, a problem that results in failure in service at a lower stress than that seen in the pre-service pressure test. This problem is caused by crack growth during the pressure test hold period, which in the case of early ERW pipe was due to a combination of low weld line toughness and lack of fusion defects.

wilsonpipeline’s fitting product of stainless steel lap joint stub end, on the hole processing method is: technology and materials. If you would know of stainless steel lap joint stub end hole method also depends on the surrounding of the hole, in general around the hole is not the disadvantage such as burr, damage, the stainless steel lap joint stub end flanging is better and easy. In today’s processing technology, stainless steel lap joint stub end hole on the data are made hole machining is smaller than the average. If you can use this mode of drilling plan will have higher production effect, but production of large hole words will let rim burr, cracks and other defects. wilsonpipeline’s fitting product: stainless steel lap joint stub end is used in punching processing, heat treatment is also used in processing after burr on the surface, hole processing, this approach can get the lower limit of flanging coefficient, but also very suitable for mass production.

For the stainless steel elbow we talked a lot, also wrote a lot, we also basically understand the various features and advantages of stainless steel elbow. Today small make up about a special term – mechanical polishing. I think most of stainless steel elbow manufacturers know what mechanical polishing, what about the polishing of the stainless steel elbow have what kind of method, after the stainless steel elbow manufacturers for many years of experience the following three types: mechanical polishing, chemical polishing, electrolytic polishing. And we are introduced by this article is the mechanical polishing. Stainless steel elbow mechanical polishing of common terms are: abrasive, grease, cutting force, etc. The stainless steel elbow process has three steps: coarse grinding, grinding and fine grinding. The polishing wheel of the stainless steel elbow is how to choose the size, because the power of the motor is decisive for the size of the polishing wheel, and motor shaft and polishing wheel to form a complete set.

ERW pipes means Electric Resistance Welded Pipes. ERW pipes and tubes are used in various engineering purposes, fencing, scaffolding, line pipes etc. ERW pipes and tube are available in various qualities, wall thicknesses, and diameters of the finished pipes.echnical requirementsFor oil and gas transport For low pressure fluid conveying  MaterialGr.bGr.b Pipe body diameter D＜508mm, ±0.75%; D≥508mm, ±0.75% D≤168.3, ±1.0%;  168.3＜D≤508,±0.75%;   Wall thicknessD＜508mm,+15.0%，－12.5%; D≥508mm, +17.5%，－10% ±12.5% Bending≤0.2% ≤0.2% Ovality D≥508mm，≤±1% ≤±0.75% Bevel ≤1.59mm ≤5mm Hydrostatic testing  100%  100%  Nondestructive testing 100% non-destructive weld inspection Ultrasonic flaw detection is 100% The technical requirements of ERW pipes Yield strength of the N80 is higher than the J55 up to 173 ~ 206 MPa. On the same area of ​​the sample, the elongation of N80 is higher than J55. Under the same size, the same sample orientation, the same minimum sample size, J55 grade couplings, coupling stock, coupling material, semi-finished and coupling attachment material can absorb lower than N80 steel grade. The nondestructive testing methods of seamless pipe,coupling stock, welded tube with J55 and N80 is differeent. J55 and N80 steel grade is not the same color: length greater than or equal 1.8m, J55 painted a bright green, N80 painted a red; J55 chosen by the manufacturer, or organize according to the order specified length normalized (N), normalizing and tempering (N & T) or quenching and tempering (Q & T). N80 is a whole, full-length heat treatment is mandatory. By the manufacturer selected for normalizing (N) or normalizing and tempering (N & T) + quenching (Q).

When the stainless steel elbow processing, whether heating or cooling, they are not consistent because the cooling rate and the time of its surface and the formation of the temperature difference. This will cause the volume expansion and contraction caused stress, called thermal stress. Stainless steel elbow Stainless steel elbow under the action of thermal stress, the surface temperature will be lower than the heart, when the end of the cooling shrinkage, not free heart finally cooling, and the surface tension of heart compression. Under the action of thermal stress, the workpiece surface pressure and the heart of tension. Thus causes this kind of phenomenon is due to the influence of cooling rate, material composition and heat treatment process. Stainless steel elbow high frequency welding is the use of the alternating current trend skin effect and proximity effect, when the steel after rolling forming, forming a section break open the round tube blank, when the tube billet near the center of the induction coil near impedor, impedance and tube formed at the opening of an electromagnetic induction loop. In the trend of the skin effect and proximity effect, blank opening edges will produce powerful and concentrated heat effect, and the edge of the weld is rapidly heated, reach the required welding temperature in the roll extrusion, the molten metal to achieve intergranular bonding, cooling after forming a firm butt weld.

This article provides an overview of electric resistance welding (ERW). It dicusses high-frequency ERW (contact and induction) and rotary wheel contact welding (AC, DC, and square wave). It describes the differences among the processes, as well as the power supplies and weld rolls. Process, power supply, and weld roll basics Several electric resistance welding (ERW) processes are available for tube and pipe production. While each process has different characteristics, all ERW processes have one thing in common–all of them produce a forged weld. A forged weld is created by applying a combination of heat and pressure, or forging force, to the weld zone. A successful forged weld uses the optimum amount of heat, which is normally slightly less than the melting point of the material, and a nearly simultaneous application of circumferential pressure to the section, which forces the heated edges together (see Figure 1). As the name implies, the heat generated by the weld power is a result of the material’s resistance to the flow of electrical current. The pressure comes from rolls that squeeze the tube into its finished shape. The two main types of ERW are high-frequency (HF) and rotary contact wheel. The Basics of HF Welding The two main aspects of HF welding are processes and power supplies. Each of these can be broken down further into subcategories. Processes. The two HF welding processes are HF contact and HF induction. In both processes, the equipment that provides the electrical current is independent from the equipment that supplies the forge pressure. Also, both HF methods can employ impeders, which are soft magnetic components located inside the tube that help to focus the weld current in the strip edges. HF Induction Welding. In the case of HF induction welding, the weld current is transmitted to the material through a work coil in front of the weld point (see Figure 2). The work coil does not contact the tube–the electrical current is induced into the material through magnetic fields that surround the tube. HF induction welding eliminates contact marks and reduces the setup required when changing tube size. It also requires less maintenance than contact welding. It is estimated that 90 percent of tube mills in North America use HF induction welding. HF Contact Welding. HF contact welding transfers weld current to the material through contacts that ride on the strip (see Figure 3). The weld power is applied directly to the tube, which makes this process more electrically efficient than HF induction welding. Because it is more efficient, it is well-suited to heavy-wall and large-diameter tube production. Power Supplies. HF welding machines also are classified by how they generate power. The two types are vacuum tube and solid-state. The vacuum tube type is the traditional power supply. Since their introduction in the early ’90s, however, solid-state units have quickly gained prominence in the industry. It is estimated that between 500 and 600 of each type are operating in North America. The Basics of Rotary Contact Wheel Welding In rotary contact wheel welding, the electrical current is transmitted through a contact wheel at the weld point. The contact wheel also applies some of the forge pressure necessary for the welding process. The three main types of rotary contact wheel welders are AC, DC, and square wave. In all three power supplies, electrical current is transferred by brush assemblies that engage slip rings attached to a rotating shaft that supports the contact wheels. These contact wheels transfer the current to the strip edges. AC Rotary Contact Wheel Welding. In an AC rotary contact wheel welding machine, the current is transferred through the brushes to the rotating shaft, which has a transformer mounted on it. The transformer reduces the voltage and increases the current, making it suitable for welding. The two legs of the transformer’s output circuit are connected to the two halves of the rotating contact wheel, which are insulated from each other. The strip completes the circuit by acting as a conductor between the two halves of the wheel. Traditional rotary contact wheel welders used 60-hertz AC, or common line current. A drawback to this system is that the current–and therefore the weld heat–rises and falls, limiting the speed at which the tube can be welded. An AC sine wave reaches its maximum amplitude briefly, producing weld heat that varies just as the sine wave does. To help even out the heat variation, motor generator sets were introduced to create AC at higher frequencies. Some of the frequencies used were 180, 360, 480, and 960 Hz. A few solid-state units also were produced to generate higher-frequency currents. An AC sine wave at 960 Hz reaches its maximum amplitude 1,920 times per second, as opposed to 120 times per second with a 60-Hz signal. The 960-Hz sine wave produces heat with a much more consistent temperature. DC Rotary Contact Wheel Welding. The next step in rotary contact wheel welding was the DC power supply. The power produced has a nearly constant amplitude. Although this solves the problem of varying heat, a major drawback is that higher maintenance costs are associated with this type of welding machine. Because it is not possible to change the voltage of DC with a transformer, it is necessary to transmit the high-amperage, low-voltage weld current into the shaft through a large number of brushes (92 for DC versus 8 for AC) with a high current density. Transmitting high-amperage, low-voltage current produces excess (waste) heat that causes heavy wear, resulting in the high maintenance costs mentioned previously. Square Wave Rotary Contact Wheel Welding. The latest step in the evolution of rotary contact wheel welding is the square wave power supply. This method combines the consistent weld heat of DC with the lower maintenance associated with AC units (see Figure 4). While rotary contact weld methods preceded the more commonly used HF welding processes, they still have a vital role in specialty welding applications. Rotary contact welding is useful for applications that cannot accommodate an impeder on the ID of the tube. Examples of this are small-diameter refrigeration-grade tube and tube that is painted on the ID immediately after the welding process. How Many Roll Units Are Needed? The types of weld pressure rolls, or squeeze boxes as they sometimes are called, that apply the pressure required for the weld are as varied as the welding units used to supply the heat. Squeeze boxes for rotary contact wheel welding typically have two or three roll units, with the contact wheel serving as one of the rolls. The number of rolls in the weld squeeze box is proportionate to the size and shape of the product being welded. There are no hard and fast rules; however, common guidelines for round tube or pipe size ranges are as follows: 3/8 to 2 in. uses two-roll units. 1/2 to 3 1/2 in. uses three-roll units. 2 to 10 in. uses four-roll units. Larger than 10 in. uses five or more rolls. Today, much more so than in the past, many shapes–square, rectangular, hexagonal–are welded in the finished shape rather than being reshaped after being welded round. The weld boxes used for the shapes are custom-designed for each application and usually have no more than five rolls.

Resistance welding is a welding technology widely used in manufacturing industry for joining metal sheets and components. Resistance welding methods are mainly four kinds, namely, spot welding, seam welding, projection welding, butt welding. Depending on the shape of the workpieces and the form of the electrodes, resistance welding processes can be classified into several variants as described below: Resistance Spot Welding Spot welding is a resistance welding process for joining metal sheets by directly applying opposing forces with electrodes with pointed tips. The current and the heat generation are localized by the form of the electrodes. The weld nugget size is usually defined by the electrode tip contact area. Spot welding is the predominant joining process in automotive industry for assembling the automobile bodies and large components. It is also widely used for manufacturing of furniture and domestic equipment etc. Resistance Projection Welding Projection welding is a resistance welding process for joining metal components or sheets with embossments by directly applying opposing forces with electrodes specially designed to fit the shapes of the workpieces. The current and the heat generation are localized by the shape of the workpieces either with their natural shape or with specially designed projection. Large deformation or collapse will occur in the projection part of the workpieces implying high process/machine dynamics. Projection welding is widely used in electrical, electronics, automotive and construction industries, and manufacturing of sensors, valves and pumps etc. Resistance Seam Welding Seam welding is a resistance welding process for joining metal sheets in continuous, often leak tight, seam joints by directly applying opposing forces with electrodes consisting of rotary wheels. The current and the heat generation are localized by the peripheral shapes of the electrode wheels. Seam welding is mostly applied in manufacturing of containers, radiators and heat exchangers etc. Resistance Butt Welding Butt welding is a resistance welding process for joining thick metal plates or bars at the ends by directly applying opposing forces with electrodes clamping the workpieces. A forging operation is applied after the workpieces are heated up. Often no melt occurs, thus a solid state weld can be obtained. Butt welding is applied in manufacturing of wheel rims, wire joints and railway track joints etc.

Pipe bend, in addition to using the standard elbow, for the most part is made of steel tube bend and stainless steel elbow. The stainless steel elbow cold bending and hot bending two kinds of methods are available, and cold bending is the tube bending method at room temperature; Hot bending pipe is heated to a certain rules under the temperature of bending forming. Cold bending is 3 in a small-bore tube bend a son; Hot bending usually also called against bending, often used in large diameter and thick wall pipe bend (e.g., high pressure pipe, etc.). It can guarantee the quality of the stainless steel elbow, stainless steel pipe fittings, before work mostly rely on manual operation, the intensity of labor is big, efficiency is low, in order to adapt to the development of chemical production, there are many kinds of special stainless steel elbow device, greatly improving the quality of the stainless steel elbow work is and efficiency. When bending the pipe, the pipe elbow of the lateral wall by stretching, the medial wall is compressed, so in the process of stainless steel elbow, it will make the outer wall thinning. This kind of phenomenon in pipe diameter under the condition of the people and the smaller the bending radius, the more obvious, in order to ensure the quality of the stainless steel elbow, avoid tube wall thickness thinning, must choose reasonably stainless steel elbow bend radius. Practice proved that for a variety of pipe bend radius can be selected according to the nominal diameter of the pipe. Should also consider the method of the stainless steel elbow and pipe wall thickness, and whether the tube fills and other factors.

ERW pipes means Electric Resistance Welded Pipes. ERW steel pipes and tubes are used. ERW steel pipes and tubes are used in various engineering purposes, fencing, scaffolding, line pipes etc. Dimensional tolerance of erw pipes: Tolerance of outside diameter Standard Out Diameter Tolerance of Pipe End Tolerance of Pipe Body API 5L 219.1-273.1 +1.6mm, -0.4mm  ±0.75%  274.0-320 +2.4mm, -0.8mm ±0.75%  323.9-457 +2.4mm, -0.8mm ±0.75%  508 +2.4mm, -0.8mm ±0.75%  559-610 +2.4mm, -0.8mm ±0.75% Tolerance of wall thickness  Standard Grade Out Diameter Wall ThicknessAPI 5L / 219.1-457 +15%, -12.5% B 508-610 +17.5%, -12.5%  X42-X80 508-610 +19.5%, -8%

The surface of the stainless steel elbow protection: 1. Stainless steel elbow with barrel, after to clear in time of weld, the heat affected zone and the surrounding the welding slag, spatter, pollutants, and the examination of the PT and surface pickling. 2. Avoid knock against scratches on the surface of the stainless steel elbow. 3. Avoid direct contact with carbon steel, avoid iron contamination. 4. Not in open air, prevent the rain. 5. Avoid compound. Structure design to prevent constraint stress. Stainless steel pickling can’t use the restore acid such as hydrochloric acid. Stainless steel head is a part of the container, according to the geometry of the different can be pided into spherical or oval, disc, ball crown type, conical shell cover and so on several kinds of peace, the spherical or oval, disc, ball crown type elbow type is referred to as convex head. Used in all kinds of container equipment, such as storage tank, heat exchanger, tower, reaction kettle, boiler and separation equipment, etc.

Stainless steel elbow in different applications, may according to the actual need, its shape is processed again, make it more convenient to use, the following specific bend deformation of six common pipe fittings of stainless steel, as follows: 1. With flange refers to the pipe end to the medial or lateral convex and circular edge: in the circumference direction of the tube form a bulge or groove pipe fittings; 2. The stainless steel elbow variable wall thickness of pipe fittings, referring to along the length direction pipe wall thickness changes; 3. Turn straight into different curvature radius of bend, such as the elbow, bend, and so on; 4. Stainless steel elbow variable diameter pipe fittings, refers to one part of the tube or pipe diameter decreased; With edge and bottom sealing tube, increase the pipe’s overall strength to pipe the inner or outer edge or the pipe end seal pipe fittings; 5. Change the pipe cross section, according to the requirements, the circular section into a square, oval, polygons, and so on. In fact, stainless steel and stainless steel elbow is straight pipe processing, deformation.