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Seamless Steel PipeshareProduct name:Seamless steel pipe, seamless pipe, seamless carbon steel pipe, carbon seamless pipe, Hot rolled seamless steel pipe, Cold drawn seamless steel pipe, smls steel pipe, cs pipe, mild steel pipe, mild smls pipe Materials:  GR.B, X42, X56, P11, P22, ST37, ST44, ST52, S235JR, S355JR, STP430. Standard:API 5L, A106, A53, A335, A333, DIN1629, DIN2448, GOST8731, JIS G3454.

https://www.slpipeline.com/Seamless-Steel-Pipes.html

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Three processes for forging pipe fittings

1. Pipe fittings die forging

For small size pipe fittings such as socket welding and threaded tees, tees, elbows, etc., their shapes are relatively complicated, and they should be manufactured by die forging.

The blanks used for die forging should be rolled profiles, such as bars, thick-walled tubes, or plates. When using steel ingots as raw materials, the steel ingots should be rolled into bars or forged and then used as blanks for die forging to eliminate defects such as segregation and looseness in the steel ingots.

The billet is heated and put into the die forging. The pressure makes the metal flow and fills the cavity. If the blank after dies forging has flash, it has to go through the step of flushing of the flash material to complete all the forging work.

2. Pipe fittings free forging

Pipes with special shapes or those that are not suitable for die forging can be manufactured by the free forging process. For free forging, the general shape of the pipe fittings should be forged, such as the tee, the branch pipe parts should be forged.

3. Pipe fittings cutting

Some tubular parts with a cylindrical shape can be directly formed by cutting rods or thick-walled tubes, such as double-socket tube hoops and unions. The fiber flow direction of the metal material should be roughly parallel to the axial direction of the pipe during processing. For tees, tees, elbows, and pipe fittings, it is not allowed to be directly formed by cutting bars.

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Hardness of precision seamless pipe

Precision seamless pipe hardness and hardness change after heat treatment Precision seamless pipe is high-quality carbon structural steel, which is not high in hardness and easy to be machined. It is commonly used in molds as templates, tips, guide posts, etc., but requires heat treatment.

No. 45 steel should not be heat treated by carburizing and quenching. After quenched and tempered parts have good comprehensive mechanical properties, they are widely used in various important structural parts, especially those connecting rods, bolts, gears that work under alternating loads, but the surface hardness is low, and they are not wear-resistant. Quenching and tempering can be used to improve the surface hardness of parts.

Carburizing treatment is generally used for heavy-duty parts with surface wear resistance and core impact resistance, and its wear resistance is higher than that of quenching and tempering. If carburizing with 45 # steel, hard and brittle martensite will appear in the core after quenching, losing the advantages of carburizing treatment. The materials that use the carburizing process now have low carbon content, which can reach very high at 0.30%, which is rare in applications.

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Carbon steel seamless pipe

Carbon steel seamless pipe is a hollow cross-section, with no seams around long steel. Steel tube with a hollow cross-section, for a large number of pipes conveying fluid, such as the transportation of oil, natural gas, coal gas, water, and some solid materials pipeline.

Solid steel such as steel pipes and round steel compared to the same flexural torsional strength while lighter, which is economic-section steel, is widely used in the manufacture of structural parts and mechanical parts, such as drill pipe, automotive transmission, bicycle frame construction using steel scaffolding. Ring with steel pipe manufacturing parts can improve material utilization and simplify the manufacturing process, saving materials and processing time, such as bearing rings, jack sets, which have been widely used to make steel.

Steel pipe or a variety of conventional weapons is an indispensable material barrel, the barrel must be steel pipe manufacturing. The steel pipe different shape of the cross-sectional area can be divided into the tube and Yixingguan. Since the equal conditions in the perimeter area of a circle with a round pipe can deliver more fluid. In addition, when subjected to internal or external radial pressure, the annular cross-sectional force is more uniform, therefore, most of the pipe is a circular tube.

Carbon steel seamless pipe is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automotive drive shafts, bicycle frames, and construction used in steel scaffolding. Ring with steel pipe manufacturing parts, can improve material utilization, simplify the manufacturing process, saving materials and processing time, such as bearing rings, jack sets, have been widely used to make steel.

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Advantages of TPEP anticorrosive steel pipe

Advantages of TPEP anticorrosive steel pipe

Product advantages:

1. TPEP anti-corrosion is an advanced anti-corrosion technology at home and abroad, and its service life is more than 50 years. The external 3PE anti-corrosion is imported from Russia. It has a history of nearly one hundred years. The internal coating uses hot-melt epoxy powder coating, which has a history of more than 70 years.

2. It can adapt well to different terrains and has good flexibility.

3. The installation is simple, the length of a single pipe can reach 12 meters, and the connection interface can be reduced by half.

4. The inner wall is smooth and dust-free, which can meet food quality requirements.

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The form and advantages of 3pe anti-corrosion steel pipe

3PE anti-corrosion steel pipe inside and outside wall anti-corrosion form

3PE anti-corrosion steel pipe refers to the 3-layer structure polyethylene coating (MAPEC) external anti-corrosion steel pipe, which is a kind of anti-corrosion pipeline commonly used in China. Other there are IPN8710, FBE epoxy powder, epoxy coal asphalt and other anti-corrosion ways. Generally refers to the outer wall of steel pipe anti-corrosion.

Steel pipe outer wall anti-corrosion form

3PE anti-corrosion generally consists of 3-layer structure.

The first layer of epoxy powder (FBE>100um)

The second layer of adhesive (AD) 170 ~ 250um

The third layer of polyethylene (PE) 1.8 ~ 3.7mm

The actual operation of the three materials mixed into one, after processing to make it and the steel pipe firmly combined to form an excellent anti-corrosion layer. Its processing method is generally divided into two kinds of winding type and round mold wrapping type.

3PE anticorrosive steel pipe coating is also known as (three-layer polyethylene anticorrosive coating), which is a new anticorrosive steel pipe coating resulting from the clever combination of 2PE anticorrosive layer in Europe and epoxy powder anticorrosive steel pipe coating (FBE) widely used in North America. It has been recognized and used all over the world for more than ten years.

The coating of 3PE anti-corrosion steel pipe is the bottom layer and the steel pipe surface contacted by the epoxy powder anti-corrosion coating, and the middle layer is the copolymer binder with branching structure functional group. The top layer is high-density polyethylene anti-corrosion coating.

3pe anti-corrosion coating integrates the high impermeability and high mechanical properties of epoxy resin and polyethylene material. So far, it is the best anti-corrosion coating for pipeline with the best effect and performance globally, and thus is used in many projects.

Steel pipe wall anti-corrosion form

Steel pipe wall anti-corrosion is divided into two types: one is hot melt epoxy resin powder anti-corrosion (high temperature fusion), a liquid epoxy coating, commonly used liquid epoxy IPN8710 (room temperature cold spray). These two forms of inner wall anti-corrosion anti-corrosion process and performance is different specifically in: drag reduction type pipeline (liquid epoxy coating) and anti-corrosion type pipeline (high temperature fusion epoxy resin powder coating), anti-corrosion pipeline used in the hot fusion epoxy coating raw materials solvent-free, food-grade powder, environmentally friendly. Anti-corrosion process is hot melt spraying, and 250 ℃ steel pipe substrate reaction, the generation of steel-plastic alloy layer. The coating thickness is higher, the corrosion resistance is stronger, the friction coefficient is lower, and the theoretical life is higher.

Uses of 3PE anti-corrosion steel pipe

For the use of 3PE anti-corrosion steel pipe many people only know one of them but not the other, its role really covers a wide range, its applicable to coal mine underground water supply and drainage, underground slurry spraying, positive and negative pressure ventilation, gas extraction, fire sprinkler and other pipeline networks. Thermal power plant process water waste slag, return water transport pipeline. It has excellent applicability for the water supply pipeline of anti-sprinkler and sprinkler system. Cable protection casing for electric power, communication, highway, etc. Suitable for high-rise building water supply, heat network heating, water supply engineering, gas transmission, buried water transmission pipeline. Process piping for oil transmission pipeline, chemical and pharmaceutical, printing and dyeing industries conveying corrosive media. Sewage treatment discharge pipe, sewage pipe and biological pond anti-corrosion project. Agricultural irrigation pipe, deep well pipe, drainage pipe and other networks and other uses, it can be said that 3PE anti-corrosion steel pipe is essential in the current construction, and I believe that through the extension of science and technology, its future still has more brilliant achievements.

Advantages of 3PE anti-corrosion steel pipe

Ordinary steel pipe in the use of a bad environment, there will be serious corrosion, which will reduce the use of steel pipe years, the service life of anti-corrosion insulation steel pipe is also relatively long, in general, can be used for about 30-50 years, and the correct installation and use can also make the network maintenance costs become low, anti-corrosion insulation steel pipe can also be set up alarm system, automatic detection of pipe network leakage failure, accurate knowledge of the location of the fault and also can be used to detect the fault. Accurate knowledge of the location of the fault and will also automatically alarm.

3PE anti-corrosion insulation steel pipe insulation performance is good, heat loss is only twenty-five percent of the traditional pipe, long-term operation can still save relatively large resources, significantly reduce energy costs, and still has a relatively strong waterproof and corrosion resistance, and also does not need to be attached to the pipe trench, directly into the ground or water, in the construction is also simple and rapid, the comprehensive cost is also relatively low, in low temperature conditions Under low temperature conditions, it also has good corrosion and impact resistance, and in a certain environment can be directly buried in the permafrost.

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Advantages and disadvantages of hot-rolled seamless steel pipe

What is hot-rolled seamless steel pipe?

Seamless steel pipe is a steel pipe made from a whole round steel perforated without welded seams on the surface, called seamless steel pipe. According to the production method, seamless steel pipe can be divided into hot-rolled seamless steel pipe, cold-rolled seamless steel pipe, cold-drawn seamless steel pipe, extruded seamless steel pipe, top tube and so on. Cold rolled seamless steel pipe is a steel pipe that is rolled below the crystallization temperature, while hot rolled seamless steel pipe is a steel pipe that is rolled above the crystallization temperature.

Advantages of hot-rolled seamless steel pipe

The casting organization of the ingot can be destroyed, refining the grain of steel and eliminating microstructural defects, so that the steel organization is dense and the mechanical properties are improved. This improvement is mainly reflected in the direction of rolling, so that the steel is no longer isotropic to a certain extent; bubbles, cracks and looseness formed during casting can also be welded together under high temperature and pressure.

Disadvantages of hot-rolled seamless steel pipe

1. After hot rolling, the non-metallic inclusions inside the steel (mainly sulfides and oxides, and silicates) are pressed into thin sheets, and the phenomenon of delamination (lamination) occurs. Delamination greatly deteriorates the properties of the steel in tension along the thickness direction, and there is a risk of interlaminar tearing during weld shrinkage. The local strain induced by weld shrinkage often reaches several times the yield point strain, which is much larger than the load-induced strain.

2. Residual stresses caused by uneven cooling. Residual stress is the internal self-equilibrium stress in the absence of external forces, a variety of cross-sectional hot-rolled steel have such residual stresses, generally the larger the cross-sectional size of the steel, the greater the residual stress. Although the residual stress is self-balancing, but the performance of steel members under the action of external forces still has a certain impact. Such as deformation, stability, fatigue resistance and other aspects may have a negative effect.

3. Hot-rolled steel products, for the thickness and edge width of this aspect is not good control. We are familiar with thermal expansion and contraction, as the beginning of the hot rolled out even if the length and thickness are up to standard, the final cooling will still appear a certain negative difference, the wider the negative side width, the thicker the performance of the more obvious. Therefore, it is impossible to be too precise about the width, thickness, length, angle, and edge line of the steel for large size steel.

Classification of hot-rolled seamless steel pipe

Hot-rolled seamless steel pipe is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, geological steel pipe and other steel pipes, etc.

Seamless steel pipe for general use: it is made of 10, 20, 30, 35, 45 and other high quality carbon knotted steel 16Mn, 5MnV and other low alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel hot rolled or cold rolled. 10, 20 and other low carbon steel seamless pipe is mainly used for fluid transportation pipeline. 45, 40Cr and other medium carbon steel seamless pipe is used to The seamless tubes made of 45, 40Cr and other medium carbon steels are used to manufacture mechanical parts, such as the stressed parts of automobiles and tractors. Seamless steel tubes are generally used to ensure strength and crush test. Hot-rolled steel pipe is delivered in hot-rolled state or heat-treated state; cold-rolled is delivered in heat-treated state.

Cangzhou Shenlong Pipe Manufacturing Co., Ltd. is an enterprise specializing in the production, processing and sales of various steel pipes and pipe fittings, with production base in Cangzhou, Hebei Province. It was founded in 1992, covering an area of more than 60,000 square meters, with more than 200 employees (including 30 inspectors) and an annual production capacity of about 150,000 tons of steel pipes and 40,000 tons of pipe fittings. We can provide first-class quality and professional technical service! Welcome to contact us! 

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How To MIG Weld Steel Tubing

What is MIG welding tubing

MIG welding plus gas as a medium to protect the metal droplet, welding molten pool high-temperature metal arc welding method and welding area, called MIG arc welding. With a solid core wire of the inert gas (Ar or He) shielded arc welding method called melting inert gas protection welding. MIG welding in addition to using metal wire instead of welding torch tungsten electrode in outside. Other and TIG welding. Therefore, the welding wire is by arc melting into the weld zone. Electric drive roller according to the welding wire from the spool needed into the welding torch. Dc electric arc heat source is, but the polarity and TIG welding is used for just the opposite. The protective gas is different and wants to join in the argon gas to be 1% oxygen to improve the stability of the arc.

Materials used in MIG welding

MIG welding has a wide range of applications. MIG welding can weld a variety of materials, but in recent years due to the carbon and low- alloy steels, and more using argon-rich hybrid GMAW welding, and rarely pure inert gas welding, metal inert gas, therefore, welding is commonly used for welding aluminum, magnesium, copper, titanium and its alloys and stainless steel. MIG welding can weld various thicknesses of the workpiece, but the actual production is generally thin plate welding, such as sheet thickness 2mm below using metal inert gas welding better. MIG welding can achieve intelligent control of all position welding.

MIG welding modes and applications

MIG welding has semi-automatic and automatic modes. Automatic MIG welding is applicable to the rules of the longitudinal seam, girth, and horizontal position of the welding; Short semiautomatic MIG welding is mostly used for tack welding, weld discontinuous welding, and aluminum container head, pipe joint, and reinforcing ring weldment of welding. Along with the expansion of MIG welding applications, only by Ar or He is difficult to meet the need of shielding gas, thus developed in an inert gas to join a small number of reactive gases such as oxygen, carbon dioxide gas mixture as shielding gas. Often called melt reactive gas, welding, or MAG. In the welding structure of production, especially in high alloy and nonferrous metals and their alloys in the production of welding, MIG welding occupies a very important position.

Recommended reading:

Stainless welded pipe

Large Diameter Welded Pipe

API SPEC 5L welded pipelines

LSAW Welded Steel Pipe

ERW Welded Steel Pipe

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Straight seam steel pipe length measurement and surface treatment

Length measurement method of straight seam steel pipe

1. Length measurement by measuring scale

The basic principle is: straight seam steel pipe outside the two ends are set up two fixed length of the scale, the use of rodless cylinder driven scale is characterized by high accuracy. However, the scale is expensive and difficult to maintain, sensitive to the impact of dust and site vibration.

2. Camera length measurement

Camera length measurement is the use of image processing to achieve the length of steel pipe measurement, the principle is to install a series of equal distance photoelectric switch on a section of the straight seam steel pipe conveyor roller conveyor, in another section with a light source and camera. When the steel pipe passes through this area, the length of the steel pipe can be determined according to the position of a photoelectric switch on the screen through the image taken by the camera.

The feature is that online measurement can be realized, and the length data can be obtained when the steel pipe passes through the length measurement area without interval. The disadvantage is that: if you do not use ad hoc light source irradiation, the steel pipe will be subject to interference from external light, and the use of ad hoc light source due to the high brightness of the steel pipe after chamfering the end of the tube and the reflection of light is very strong, easy to cause reading errors.

3. Encoder length measurement

The principle is to install the encoder at the cylinder, using the cylinder to push the steel pipe in the roller conveyor movement, on the other side of the installation of a series of equal distance photoelectric switch, when the steel pipe is pushed by the cylinder end touches the photoelectric switch, from the recorded encoder readings, converted to the cylinder stroke, so that the length of the steel pipe can be calculated.

The characteristic is that the steel tube needs to be lifted when measuring the length. In addition, there is some error in photoelectric switch detection, which may require full measurement.

4. Improved encoder length measurement

This method is an indirect measurement method, by measuring the distance between the two ends of the steel pipe and the respective reference point, the length of the steel pipe is measured indirectly. At each end of the steel pipe set up a length measurement trolley, the initial position of zero, the spacing is L. Then move the editor length to the respective pipe end of the walking distance (L2, L3), L - L2 - L3, that is, the length of the steel pipe.

This measurement method to overcome the huge size of the steel pipe, the production site environment is complex, the measurement mechanism can not cross the lower steel pipe support bench and other difficulties. This method is easy to operate and the measurement accuracy is within ±10mm, with a repeatability of ≤5mm.

Surface treatment of straight seam steel pipe

With the continuous development of China's economy, the country vigorously develop the energy industry, long-distance oil and gas pipeline is an important way of energy security, in the process of oil and gas pipeline anti-corrosion construction, straight seam steel pipe surface treatment is one of the key factors to determine the service life of the pipeline anti-corrosion, it is the premise that the anti-corrosion layer and steel pipe can be firmly combined. Verified by research institutions, the life of the anti-corrosion layer in addition to the type of coating, coating quality and construction environment and other factors, straight seam steel pipe surface treatment on the life of the anti-corrosion layer of about 50% of the impact, therefore, should be strictly in accordance with the requirements of the anti-corrosion layer specification for the surface of the steel pipe, continuous exploration and summary, and constantly improve the surface treatment of steel pipe.

1.cleaning of straight seam steel pipe The use of solvents, emulsions to clean the steel surface to remove oil, grease, dust, lubricants and similar organic substances, but it can not remove the steel surface rust, oxide skin, welding powder, etc., and therefore only as an auxiliary means in the production of anti-corrosion.

2. tool rust removal of straight seam steel pipe Mainly using tools such as wire brushes to polish the steel surface, which can remove loose or buckled oxidation, rust, weld slag, etc. Manual tool rust removal can reach Sa2 level, power tool rust removal can reach Sa3 level, if the steel surface is firmly attached to the iron oxide skin, tool rust removal effect is not ideal, not up to the depth of the anchor pattern required for anti-corrosion construction

3. Pickling of straight seam steel pipe Generally, two methods of chemical and electrolytic pickling are used to do the pickling treatment, and only chemical pickling is used for pipeline corrosion protection, which can remove the oxide skin, rust and old coating, and sometimes it can be used as reprocessing after sandblasting rust removal. Although chemical cleaning can make the surface reach a certain degree of cleanliness and roughness, its anchor pattern is shallow, and it is easy to cause pollution to the environment.

Cangzhou Shenlong Pipe Manufacturing Co., Ltd. is an enterprise specializing in the production, processing and sales of various steel pipes and pipe fittings, with its production base located in Cangzhou, Hebei Province. It was founded in 1992 and covers an area of more than 60,000 square meters. Our products are exported to the Middle East, Europe, Africa and America, and are widely used in the fields of oil mining, chemical industry, water conservancy, construction and so on. We can provide first-class quality and professional technical service! Welcome to contact us! 

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Flange

Flange type: integral pipe flange, steel pipe flange, threaded flange, slip-on flange (SO) slip-on welding flange,socket welding flange, lap joint flange (LJF), welding neck flange (WNF), blind flange, orifice flange.

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DIFFERENT USES OF STEEL WITH DIFFERENT TECHNICAL CONDITIONS

General seamless steel tubes for conveying water, gas, oil pipelines and manufacture of fluid structural components, the response to its mechanical properties such as tensile strength, yield strength and elongation for the sample test. Duct generally work under conditions of pressure, also called pressure test done and flaring, squash, curling and other process performance tests. For large-scale long-distance crude oil, refined oil, natural gas pipelines with a pipe is to increase the carbon equivalent, welding performance, low-temperature toughness, stress corrosion under harsh conditions, corrosion, corrosion fatigue strength and corrosion environment and other requirements. Ordinary boiler tubes used in the manufacture of structural steel pipe and superheated steam boilers boiling water pipes. High-pressure boiler tubes for high pressure or high pressure superheated steam boilers, heat exchangers and pipes for high pressure equipment.

The steel thermal equipment in different conditions of high temperature and pressure of work, should ensure good surface condition, mechanical and technological properties. Generally to test its mechanical properties, flattening, and hydrostatic testing to do, high-pressure boiler tubes also asked to do the test and the grain size of more stringent non-destructive testing. Mechanical seamless steel pipe according to the application requirements to be a higher dimensional accuracy, good mechanical properties and surface condition. Regulatory requirements such as bearing high wear resistance, homogeneous, and strictly within the diameter tolerance. In addition to doing general mechanical performance test items, we need to do low-magnification, fracture, annealing (ball of the organization, mesh light, strip), non-metallic inclusions (oxides, sulfides, dot, etc.), de- indicators of carbon layer and its hardness test. Fertilizer industry often use high pressure seamless steel pressure of 2200 ~ 3200Mpa, working temperature -40 ℃ ~ 400 ℃ and the corrosive environment, transport chemical medium (such as ammonia, methanol, urea, etc.). Fertilizer industry with high-pressure seamless steel pipe should have a strong corrosion resistance, good mechanical properties and surface condition. In addition to doing mechanical properties, flattening, and hydrostatic testing, it should be based on different kinds of steel corrosion test streamlined accordingly, managers and more rigorous degree of non-destructive testing. Petroleum, geological drilling pipe at high pressure, alternating stress, corrosive, harsh environments, it should be a high intensity level, and to wear, torsion and corrosion-resistant properties. According to the different grades of steel should be done tensile strength, yield strength, elongation, impact toughness and hardness tests. Used for oil well casing, tubing and drill pipe, is a detailed breakdown of the grade, category, and for different environmental, geological conditions selected by the user’s own additional requirements for high technical requirements, to meet different specific needs. Chemical, petroleum cracking, aviation and other machinery industry with a variety of acid-resistant stainless steel pipe and mechanical properties than do the pressure test, but also specifically for the intergranular corrosion test, flattening, flaring and non-destructive testing and other tests.

Cangzhou shenlong pipe pipe manufacture is a premier worldwide source for carbon steel pipes, stainless steel tube, seamless pipes,  welded pipe, galvanized tubes, casing pipes and steel fittings.

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CAUSES AND MEASURES OF PIPE WELD POROSITY

Cangzhou shenlong pipe manufacture is a premier worldwide source for carbon steel pipe, stainless steel tube, seamless pipes, welded pipes,galvanized tubes,casing pipes and steel fittings.

Weld pipeweld porosity affects not only the pipeline denseness, resulting pipeline leakage and corrosion will be induced point seriously reduce the weld strength and toughness. Factors weld porosity are: the flux in the water, dirt, oxide and iron filings, welding ingredients and cover thickness, surface quality steel and steel side plates processing, welding technology and steel molding processes.

Related prevention measures

1. Flux ingredients. CaF2 and SiO2 containing an appropriate amount of welding, the reaction will absorb large amounts of H2, generating a high stability of the HF insoluble in the liquid metal, thereby preventing the formation of hydrogen gas holes.

2. The bulk thickness of the flux is generally 25-45mm, large solder particle size, bulk density hour take the maximum thickness, whereas the minimum value; high current, low welding speed accumulation take the maximum thickness, whereas the minimum value addition, summer or air humidity, flux recovery should be dried before use.

3. The surface-treated steel sheet. To avoid open-book leveling off oxide scale and other debris into the molding process, the board should be set cleaning device.

4. Steel plate edge processing. Steel plate edge should be set rust and burr removal device to reduce the possible generation of holes. Removing device installed in the best position after the milling machine and disc shear, the structure of the device is the active wire wheel side two up and down position adjustable gap, the upper and lower clamping plate edge.

5. Weld profile. Weld forming factor is too small, narrow and deep weld shape, gas and inclusion is not easy to leak out, easy to form pores and slag. General weld coefficient control in 1.3-1.5, thick-walled pipe maximum value, minimum value of thin-walled.welded pipe

6. Reduce secondary magnetic field. To reduce the influence of magnetic blow should be made on the workpiece welding cable connection location only possible away from the welding terminal, to avoid some welding cable secondary magnetic field generated in the workpiece.

7. Workmanship. Should be appropriate to reduce or increase the speed of the welding current, thereby delaying the crystallization rate of the weld metal bath in order to facilitate the escape of gas, at the same time, if the strip delivery location instability, should be timely adjusted to eliminate frequent fine-tuning after the adoption of the front axle or bridge to maintain molding, causing gas to escape difficult.

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BURIED NATURAL GAS PIPELINE ANTI-CORROSION TECHNOLOGY

The high anticorrosion coating application

The primary means of domestic and international underground natural gas pipeline corrosion is appropriate based on the pipeline the geographical terrain, topography, geological conditions, covering supplemented by cathodic protection. Used paint: petroleum asphalt, coal tar enamel, epoxy paint. Domestic buried pipeline anti-corrosion commonly used petroleum asphalt paint. If the soil environment, microbial, no serious interference with the deep-rooted plants, be regarded as an affordable anti-corrosion layer. Its flow properties are not suitable for high-temperature environment and serious pollution of the environment during the construction, its use has shown a downward trend. From a global perspective, the most widely used when push coal tar enamel and epoxy paint. The former has a strong anti-microbial corrosion, anti-plant root penetration, low water absorption, resistance to cathodic delamination, bonding wrapped solid strong on the wall, there are obvious advantages for use in the oil and gas pipeline The United States, Russia, in the large-scale use.

Pipeline coating the front surface pretreatment process

The preservative quality depends on the level of the coated front surface pretreatment method selection. The traditional degreasing rust Law of time and labor pollution is difficult to guarantee quality. In recent years the tendency to use high temperature unglazed law degreasing, the pipe loading into specially furnace at 350 ~ 400 ℃ supplemented with ventilation, insulation 3 ~ 4 h, the oil burned guarantee degreasing quality. Peening machinery instead of the traditional method of pickling. This method is the use of compressed air to carry steel shot (or sand) to form a high-speed flow of logistics strong impact on the steel surface through the nozzle of the gun to remove oil or oxide. It rust completely, but also improve the surface roughness, to increase the contact area of the wall and the coating (about 20 times), and to improve coating bond strength, can be effectively prevented deep delamination.

Cangzhou Shenlong pipe manufacture is a premier worldwide source for carbon steel pipe, coated pipeline, seamless pipes, welded pipes,galvanized tubes,casing pipes and steel fittings.

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Coated Steel Pipe

Coated steel pipe type:

3PE coated steel pipe, 3PP coated steel pipe, Epoxy coated steel pipe, FBE coated steel pipe, Insulated thermal insulation steel pipe, Coating plastic steel pipe, Polyurethane insulation steel pipe

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Carbon steel pipe internal defects

Carbon steel pipe internal defects are generated in the carbon steel smelting defect smelting and casting processes, such as segregation, non-metallic inclusions, porosity, shrinkage, and cracks.

Segregation

Segregation is the uneven distribution of chemical composition in the steel, in particular harmful elements such as sulfur, phosphorus enrichment in the ingot.

Non-metallic inclusions

Non-metallic inclusions refer to non-metallic inclusions in steel containing impurities such as sulfides and oxides.

Stomata

Stomata refer to iron and carbon monoxide gas effect generated in the pouring can not fully escape and stay in the tiny pores in the ingot.

Shrinkage

Shrinkage is due to the liquid steel ingot mold from outside to inside, the volume contraction during solidification bottom-up, because the level drops, the final solidification of liquid steel parts can not be added to form.

Crack

Solidification of liquid steel in the order due to different causes stress, tension cracks may appear larger parts.

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Large-diameter steel pipe forming method

1. Hot push system expansion method

Pushing and expanding equipment is simple, low-cost, easy to maintain, economical and durable, flexible product specifications change, if you need to prepare large diameter steel pipes and similar products, only need to add some accessories. It is suitable for the production of medium and thin-wall thick large-diameter steel pipes, as well as thick-walled pipes that do not exceed the capacity of the equipment.

2. Hot extrusion method

Before extrusion, the blanks need to be machined and pre-processed. When extruding pipes with a diameter of less than 100mm, the equipment investment is small, the material waste is small, and the technology is relatively mature. However, once the diameter of the pipe is increased, the hot extrusion method requires large-tonnage and high-power equipment, and the corresponding control system must also be upgraded.

3. Hot piercing and rolling method

Hot piercing rolling is mainly based on longitudinal rolling and cross rolling. Longitudinal rolling extension rolling mainly includes rolling with limited mandrel continuous rolling tube, rolling with limited stand mandrel continuous rolling tube, rolling with three-roll limited mandrel continuous rolling tube, and rolling with floating mandrel continuous rolling tube. These methods have high production efficiency, low metal consumption, and good products, and the control system is increasingly used.

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SEAMLESS STEEL PIPES COMMONLY NDT METHODS

1. seamless steel tube magnetic particle testing (MT) or magnetic flux leakage testing (EMI)

The detection principle is based on the ferromagnetic material is magnetized in a magnetic field, the discontinuity of the materials or products (defect), magnetic flux leakage, magnet powder adsorption (or detected by detector) was revealed (or displayed on the instrument). This method can only be used for ferromagnetic materials or surface or near-surface defects testing of products.

2. seamless steel tube penetration test (PT)

Includes fluorescent, colored in two ways. Because of its simple, convenient operation, is for lack of magnetic particle inspection test effective methods for surface defects. It is mainly used for inspection of surface defects of non-magnetic material.

Principles of fluoroscopy are checked products will be immersed in a fluorescent liquid, due to capillary phenomenon of seamless steel tubes, filled with fluorescent liquid in the defect, get rid of the liquid on the surface, due to light-induced effects, liquid fluorescent under ultraviolet light revealed defects.

Dye penetrant inspection of the theory and principles of fluoroscopy is similar. Is no need for special equipment, just use defects Imaging powder adsorption in liquid coloring in manifest suction surface defects.

3. seamless steel pipe ultrasonic testing (UT)

This method is the use of ultrasonic vibration to find materials or parts inside (or surface) defects. Depending on the ultrasonic vibration method can be divided into CW and pulsed wave; according to the different modes of vibration and propagation can be divided into p-wave and s-wave and surface waves and lamb waves 4 form in the workpiece spread; according to the different sound transmission and reception conditions, and can be divided into single probe and probe.

4. seamless steel tube for Eddy current testing (ET)

Eddy current detection of alternating magnetic field produces the same frequency of the Eddy current in the metal, using the Eddy-current the size relationship between the resistivity of metallic materials and to detect defects. When surface defects (cracks), the resistivity will increase the presence of defects, associated with Eddy-current is reduced accordingly, small change after enlargement of the Eddy current instruments indicated, will be able to show the existence and size of defects.

5. seamless steel tube radiographic testing (RT)

One of the earliest methods of non-destructive testing, is widely used in metal and non-metal materials and products for internal defects testing, at least more than 50-year history. It has incomparable advantages, namely test defects, reliability and intuitiveness, radiographic and will be used for defect analysis and as a quality document archive. But this way there are more complex, higher-cost disadvantage, and should pay attention to radiation protection

Cangzhou shenlong pipe pipe manufacture is a premier worldwide source for carbon steel pipes, stainless steel tube, seamless pipes,  welded pipe, galvanized tubes, casing pipes and steel fittings.