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This technical specification is suitable for the bidding for the procurement of steel pipe projects. Executive standards The steel pipe shall meet the following standards: Quality standard like Spiral Welded Submerged Arc Welded Steel Pipes for Urban Heating CJ/T3022-1993 or Technical Delivery Conditions of Oil and Gas Industry Transportation Steel Pipes GB/T9711.1-2017 should be implemented for spiral welded pipes. Seamless Steel Pipe for Fluid Transportation GB/T8163-2008 should be carried out as quality standards for seamless steel pipes. Technical requirements for steel pipes Materials The steel pipe should be made of spiral seam welded steel pipes with Q235B.  The seamless steel pipe should adopt 20# steel. Technical specifications The quality and size of spiral seam welded steel pipes should conform to IS09330-1 or GB9711.1～2017 standards. Spiral seam welded steel pipes should ensure that the minimum yield strength is greater than 235N/mm2. Weld joints of steel pipes must meet the technical requirements of DIN1626 or GB3323-87. Specifications, weights and errors of steel pipes The supply of steel pipes shall comply with the relevant regulations in the latest GB9711.1-2017 or GB8163-2008. The normal supply length of the steel pipe should be 12m with a length deviation of 0/+25mm.  When the length of the steel pipe is less than 12m due to the valve, compensator or pipeline turning, it should be supplied according to the actual length on site. The thickness deviation requirements of the raw material steel plate of the steel pipe: when DN is 800mm, the negative thickness deviation should be smaller than or equal to 0mm.  When DN is greater than 800 and smaller than or equal to 1100mm, the thickness negative deviation should be less than or equal to 0mm.  When DN is greater than 1100 and smaller than or equal to 1200mm, the thickness negative deviation should be less than or equal to 3%. The end of the steel pipe should be grooved.  The groove angle should be 30° and the deviation 0°/5°.  The size of the blunt edge should be 1.6±0.8mm. The end surface of the steel pipe shall be perpendicular to the axis of the steel pipe.  When the nominal outer diameter is less than 508mm, the limit deviation shall not be greater than 1.5mm.  When the nominal outer diameter is greater than or equal to 508, the limit deviation shall not be greater than 2.0mm. The ovality of the steel pipe end within 100mm shall not exceed ±1%D. Requirements for manufacturers In order to ensure the quality of the project, the following requirements are put forward for the materials and manufacturers of steel pipes and fittings: The steel quality standards of steel pipes are equal to or higher than those of famous steel pipe manufacturers in China. The quality standard of the steel pipe is equal to or higher than the product standard produced by the bidder, and the selected manufacturer must be approved by the tenderer and indicate in the bidding document. At the same time, photocopies of the delivery quality certificate of the steel pipe raw materials, the quality certificate of the steel pipe, the special equipment manufacturing license (pressure pipe) that the manufacturer should have, and the inspection report issued by the local quality inspection department must be attached to the bidding documents.

Materials of alloy steel pipes Alloy steel pipes have good hardness, which are widely used for pipelines for transporting oil, natural gas, gas, water and certain solid materials. The common alloys are ferroalloys, ferro-chromium alloys, iron-nickel alloys, aluminum alloys(light weights) and copper alloys(good thermal conductivity). The main materials include 16-50Mn, 27SiMn, 20-40Cr, 12-42CrMo, 16Mn, 12Cr1MoV, T91, 27SiMn, 30CrMo, 15CrMo, 20G, Cr9Mo, 10CrMo910, etc. Alloy steel pipes made from 16Mn belong to low alloy steel pipes. Applications of alloy steel pipesAlloy steel pipes are mainly used for high-pressure and high temperature pipelines and equipment such as power plants, nuclear power, high-pressure boilers, high temperature superheaters and reheaters. Three expressions of alloy steel pipe specifications 1. The first one is the outer diameter plus wall thickness. For example, an alloy steel pipe with an outer diameter of 57mm can be indicated by 57x3. 2. The second one is using the inner diameter, that is, the nominal inner diameter. For example, an alloy steel pipe with an outer diameter of 57mm is indicated by DN50. 3. The third one is the inch. For example, an alloy steel pipe with an outer diameter of 57mm can be indicated by 2 inches (1 inch equals to 25.4mm.)  Specific welding steps of alloy steel pipesWelding processes of alloy steel pipes are heating before welding, quenching and tempering after welding. HeatingBefore welding the alloy steel pipe, it should be heated, and weld it after the temperature is controlled for 30 minutes. The heating and virtual beam temperature tempering of welding are actively operated by the temperature control cabinet for temperature adjustment. Adopt far infrared tracking heat treatment furnace plates. Intelligently and actively set the graph and record the graph, and use the thermal resistance to accurately measure the temperature. The thermal resistance measuring point is from 15mm to 20mm away from the edge of the weld during heating. Welding methods1. In order to prevent welding deformation of the alloy steel pipe, each column joint is welded symmetrically by two people, and the welding direction is from the middle to the two sides. After welding one to three layers, reverse planing should be carried out. After the carbon arc gouging is used, the welding equipment needs to be polished. The welding surface should be nitridation treated to show the metal texture and prevent the surface carbonization from causing cracks. The outer hole is welded once, and the remaining inner holes are welded once. 2. When welding alloy steel pipes with two layers, the welding direction should be opposite to that of the layer of alloy steel pipes. The butt welds of each layer are separated by 15 to 20mm.3. The welding current, welding speed and number of overlapping layers of multiple welding machines should be maintained.4. In welding, you must start welding from the pilot arc board and finish welding on the pilot arc board. Cut, polish and clean after welding.  Quenching and tempering after weldingAfter the seam are welded, it should be tempered within 12 hours. If the alloy steel pipe cannot be quenched and tempered immediately, heat preservation and slow cooling should be adopted. When the alloy steel pipe is tempered, temperatures of the two thermal resistances should be measured and the thermal resistance should be welded on both sides of the seam.

It mainly uses steel wire brush and other tools to polish the steel surface, which can remove loose or raised oxide skin, rust, welding slag, etc. Generally, chemical and electrolytic methods are used for pickling treatment. Chemical pickling is only used for pipeline corrosion protection, which can remove oxide skin, rust and old coating. Sometimes it can be used as the reprocessing after sand blasting. Although chemical cleaning can make the surface reach a certain degree of cleanliness and roughness, its anchor pattern is shallow and easy to pollute the environment. Spray (throwing) rust removal is a high-speed rotation of spray (throwing) blades driven by a high-power motor, so that steel sand, steel shot, wire section, minerals and other abrasives can spray (throwing) on the ASTM A106 A53 Gr. B Carbon Steel Seamless Fluid Pipe surface under the centrifugal force, which can not only completely remove rust, oxides and dirt, but also achieve the required uniform roughness under the action of strong impact and friction of abrasives. After spraying (throwing) and removing rust, not only the physical adsorption on the pipe surface can be expanded, but also the mechanical adhesion between the anticorrosive coating and the pipe surface can be enhanced. Therefore, spraying (throwing) is an ideal way to remove rust. Generally speaking, shot blasting (sand) is mainly used for inner surface treatment of pipes, while shot blasting (sand) is mainly used for outer surface treatment of pipes.

Hot dip galvanized steel pipe is widely used in construction, machinery, coal mine, chemical industry, electric power, railway vehicles, automobile industry, highway, bridge, container, sports facilities, agricultural machinery, petroleum machinery, prospecting machinery and other manufacturing industries. ASTM A53 Galvanized Steel Pipe is a welded steel pipe with hot-dip or electro galvanized surface.  Galvanizing can increase the corrosion resistance of steel pipe and prolong its service life.  The galvanized pipe is widely used, not only as the pipeline for water delivery, gas, oil and other general low-pressure fluid, but also as the oil well pipe and oil pipe of the petroleum industry, especially the offshore oil field, the oil heater, condensate cooler, coal distillate wash oil exchanger pipe of the chemical coking equipment, as well as the trestle pipe pile, the support frame pipe of the mine tunnel, etc.   ASTM A53 Galvanized Steel Pipe is to make molten metal react with iron matrix to produce alloy layer, so that the matrix and coating are combined.  Hot dip galvanizing is to pickle the steel pipe first, in order to remove the iron oxide on the surface of the steel pipe, after pickling, it is cleaned by ammonium chloride or zinc chloride aqueous solution or the mixture of ammonium chloride and zinc chloride aqueous solution tank, and then it is sent into the hot dip galvanizing tank.  Hot dip galvanizing has the advantages of uniform coating, strong adhesion and long service life.  

Seamless steel pipe is a kind of long steel with hollow section and no joint around.  The seamless steel pipe has hollow section and can be used as the pipeline for conveying fluid, such as oil, natural gas, gas, water and some solid materials.  Compared with solid steel such as round steel, seamless steel pipe is lighter in weight when its bending and torsion strength is the same.  It is a kind of economic section steel, which is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffold used in construction.  Using seamless steel pipe to make annular parts can improve the material utilization rate, simplify the manufacturing process, save materials and working hours, such as rolling bearing rings, Jack sleeves and so on.  Steel pipe is also an indispensable material for all kinds of conventional weapons.  Gun barrel and barrel should be made of steel pipe.   According to different production methods, it can be divided into hot-rolled pipe, cold-rolled pipe, cold drawn pipe, extruded pipe, etc. 1.Hot rolled seamless steel pipe is usually produced on the automatic pipe mill.  After checking and removing the surface defects of the solid tube blank, it is cut into the required length, centring on the end face of the piercing end of the tube blank, and then sent to the heating furnace for heating and piercing on the piercing machine.  In the process of piercing, a cavity is gradually formed inside the tube blank under the action of the roller and the plug, which is called the blank tube.  Then it is sent to the automatic pipe rolling mill to continue rolling.  Finally, the wall thickness is adjusted by the whole machine, and the diameter is calibrated by the sizing machine to meet the specification requirements.  It is an advanced method to produce hot rolled seamless steel tube by continuous pipe mill. 2.  In order to obtain smaller size and better quality seamless tubes, cold rolling, cold drawing or a combination of both must be used.  Cold rolling is usually carried out on a two high mill.  The steel tube is rolled in an annular pass composed of a variable cross-section circular groove and a stationary conical plug.  Cold drawing is usually carried out on 0.5-100t single chain or double chain cold drawing machines.   3.  In extrusion process, the heated tube blank is placed in a closed extrusion cylinder, and the piercing rod and the extrusion rod move together to extrude the extruded part from the smaller die hole.  This method can produce small diameter steel pipe.

1. Using the three-dimensional space simulation module, the three-dimensional coordinate system of the curved surface is established according to the relationship between the curved surface and the building axis provided by the original design drawings, and the three-dimensional structure diagram of the hyperbolic arc roof is drawn. Three dimensional structural drawing of arc roof.  2. According to the load calculation, the vertical pole spacing and horizontal pole step distance of steel pipe scaffold for roof construction are determined, and the steel pipe scaffold is simulated and positioned in the three-dimensional structure diagram. Pre positioning of steel pipe scaffold.  3. The intersection of the vertical pole of the steel pipe scaffold and the horizontal pole of the steel pipe scaffold is generated into a plane projection grid line on the hyperboloid. Generate the steel pipe grid projection line.  4. Calculate the elevation of the corresponding point on the spatial hyperboloid at each grid node in the horizontal projection plane coordinate system.  5. Record the three-dimensional coordinates, grid point spacing and other parameters of all intersections.  

To determine the size of a flange, you will need to measure the diameter of the flange.  Here's how you can do it: 1.  Measure the outside diameter (OD) of the flange: Use a measuring tape or a caliper to measure the distance across the outer edge of the flange.  Make sure to measure from one side to the opposite side, passing through the center. 2.  Determine the flange size: Once you have the measurement of the outside diameter, you can refer to a flange size chart or consult the manufacturer's specifications to determine the corresponding flange size. It's important to note that flange sizes are typically specified in standard dimensions, such as inches or millimeters.  Additionally, some flanges may have specific designations based on their intended application or industry standards (e.g., ANSI, ASME, DIN, etc.). If you're unsure or need accurate measurements, it's recommended to consult a professional or refer to industry standards for precise flange sizing.        

Today, let's talk about the elbow - a very common and humble pipe fitting. The elbow plays a very important role in the pipeline system, which can realize the bending and steering of the pipeline system. If there is no elbow our life will become very inconvenient! First of all, let me introduce the classification of elbow. Elbows are divided into long elbows and short elbows according to the bending Angle and radius of the pipe. Long elbow is used for small radius bending, and short elbow is generally used when the radius is relatively large. There is also a elbow called a tee, as the name suggests, is a three-tube mouth elbow. Elbow also has a very important indicator - the strength of the elbow. The strength of the elbow depends on its material and production process. When we choose the elbow, we need to choose the elbow strength according to the use environment and force situation of the pipeline. Under normal circumstances, we will choose a high-strength elbow to ensure the stability of the pipeline. So, what are the other advantages of the elbow? First of all, the elbow can play a role in sound insulation and shock absorption. In the pipeline system, the elbow can reduce the noise and vibration of the water flow, so as to ensure the comfort of living and working.Secondly, the elbow can adapt to the needs of pipe steering and bending. In different pipeline systems, the Angle and direction of bending are different, and the design of the elbow can make the pipeline system more flexible and diverse without affecting the connection of the pipeline. Finally, the material and production process of the elbow can affect the corrosion resistance and service life of the piping system. Therefore, when selecting the elbow, we need to consider the use of the pipeline environment and requirements, choose the appropriate elbow material and production process. In short, although the elbow looks unremarkable, it is an indispensable part of the pipeline system. Choosing the right elbow can ensure the stability, tear resistance and service life of the piping system. In the purchase of elbow, we need to consider the strength of the elbow, material, production process and use of the environment and other factors.

Carbon steel flange is a kind of common connecting pipe component, which is widely used in petroleum, chemical, natural gas and other industries. It is usually made of carbon steel, with high strength, corrosion resistance and high temperature characteristics, suitable for a variety of harsh working environment. There are many types of carbon steel flanges, including blind plate, butt welding, thread, flange, etc. . Each type has a different way of connecting and usage scenarios to meet a variety of different needs. Butt-welding flange is the most common one, it can be fixed to the pipeline through welding to ensure the stability and sealing of the connection. Thread flange is suitable for low pressure environment, through the thread connection to achieve pipe connection. Blind flange used to block the flow of fluid in the pipeline, often used for pipeline closure or repair. One of the advantages of carbon steel flanges is that the material strength is high, able to withstand high pressure and high temperature working conditions. It can be used in harsh environment for a long time, with a long life. The carbon steel flanges also have good corrosion resistance and are not easy to be corroded and oxidized when in contact with various media, thus ensuring the safety and reliability of pipelines. Carbon steel flanges are relatively simple to install and maintain and can be quickly removed and replaced. Its structure design is reasonable, has the good sealing, can prevent the leakage and the outside impurity entering. At the same time, carbon steel flanges have lower cost and play an important role in the design and construction of pipeline system. In a word, as an important part of connecting pipeline, carbon steel flange has the characteristics of high strength, corrosion resistance and high temperature resistance. The utility model has the advantages of reasonable structure design, simple installation, good sealing performance and lower cost, and is widely used in petroleum, chemical industry, natural gas industry and the like. Carbon steel flanges are a reliable and economical choice for both new construction and maintenance projects.

Summary: This article highlights the importance and applications of carbon steel elbows as fittings for steel pipe connections. Compared to other materials, carbon steel elbows offer affordability, lightweight construction, and easy installation. Selecting the specifications for these elbows ensures optimal sealing and minimizes stress damage risk. Additionally, the flanged or threaded ends enable secure connections with straight pipes and fittings. In conclusion, carbon steel elbows provide efficient and reliable solutions for pipe connections, enhancing safety and prolonging the lifespan of the pipeline system. Elbows are one of the important fittings in steel piping systems. As a connector for pipe turns, elbows allow pipes to make smooth directional changes. Choosing suitable elbows can improve the safety and service life of piping systems. Carbon steel elbows are commonly used fittings for steel pipes. Compared to stainless steel or cast iron elbows, carbon steel elbows are more economical, lightweight, and easy to fabricate and install. Carbon steel elbows are suitable for most steam, water, gas and other piping systems, especially widely used in general industrial and heating applications. The main specifications of carbon steel elbows include pipe size, wall thickness and elbow radius. Different elbow sizes can meet various pipe turning needs. Choosing proper elbows not only ensures sealing performance of the piping system, but also reduces risk of stress damage to the pipes. In addition, the flanged or threaded ends on the elbows can make reliable sealed connections with straight pipes and other fittings. In summary, carbon steel elbows provide economical and practical pipe connection solutions. Reasonable selection and installation of carbon steel elbows can improve safety, sealing and service life of piping systems. Key Words:90 degree elbow pipe ,90 degree elbow formula ,90 degree elbow,45 elbow,Carbon steel elbow,steel elbow,Stainless steel elbow,SS304,SS316,B16.9,GOST17375