The method of using ultrasound to detect instrument called ultrasonic flaw detector. Its principle is: when the ultrasonic wave propagation in the detected material changes in the acoustic properties and the internal organization of the material have a certain effect on the propagation of ultrasonic waves through the ultrasonic affected degree and condition detection understanding material properties and structural changes of technology called ultrasonic testing. Ultrasonic testing methods typically penetrating, pulse reflection method, serial method. Penetrating ability, depth of up to several meters;
x-rays can not penetrate conventional visible light through the material. The strength of its ability to penetrate, and x-ray wavelengths and is penetrated material density and thickness. x-ray wavelength shorter, the greater penetration; the lower the density, the thinner the thickness of the x-rays to penetrate more easily. In practice, the value of the voltage V balls tube (kV) to determine the size of the x-ray penetration (ie, x-ray quality), and to the unit of time through the x-ray current (mA) and the time the product Representative x-ray amount. The maximum thickness can be measured with the x-ray intensity, generally metal thickness of 0.3 m or less;
The advantages of ultrasonic testing than X-ray flaw detection:
It has high sensitivity, short cycle, low cost, flexible, high efficiency, harmless to human body and so on;
Ultrasonic testing disadvantages compared to X-ray detection of:
On the work surface smoothing requirements, requirements experienced inspectors to identify the type of defect, the defect does not intuitive;
Ultrasonic testing is suitable for large thickness parts inspection.
2016年7月30日星期六
Pipe Joint Bonding
Welded pipe joints suitable medium: oil, water, gas and other non-corrosive or corrosive media welded seal fittings, with requirements for more flexible steel pipe specifications, pipe welding and after having a solid connection, good sealing performance.
It has been widely used in oil refining, chemicals, light industry, textile, defense, metallurgy, aviation, shipping and other systems; also applies to a variety of mechanical engineering, machine tools and other hydraulic transmission pipeline. When the bite type pipe joint production can not meet the needs, as well as corrosion strong case can be considered a priority. Welded pipe joints manufacturing standards
1,the metal fittings O-ring plane for fluid power and general use of sealing joints (JB / T 966-2005)
2,cone seal welded straight couplings (JB / T 6381.1-2007)
3,cone seal welded straight 55 °non-sealing pipe thread fittings (JB / T 6381.2-2007)
4,cone seal welded straight 55 °sealing pipe thread fittings (JB / T 6381.3-2007)
5,cone seal welded straight 60 °sealing pipe thread fittings (JB / T 6381.4-2007)
6,cone seal welded 90 °elbow (JB / T 6382.1-2007)
For more, please visit the website:http://www.hu-steel.com/news355_320.html
It has been widely used in oil refining, chemicals, light industry, textile, defense, metallurgy, aviation, shipping and other systems; also applies to a variety of mechanical engineering, machine tools and other hydraulic transmission pipeline. When the bite type pipe joint production can not meet the needs, as well as corrosion strong case can be considered a priority. Welded pipe joints manufacturing standards
1,the metal fittings O-ring plane for fluid power and general use of sealing joints (JB / T 966-2005)
2,cone seal welded straight couplings (JB / T 6381.1-2007)
3,cone seal welded straight 55 °non-sealing pipe thread fittings (JB / T 6381.2-2007)
4,cone seal welded straight 55 °sealing pipe thread fittings (JB / T 6381.3-2007)
5,cone seal welded straight 60 °sealing pipe thread fittings (JB / T 6381.4-2007)
6,cone seal welded 90 °elbow (JB / T 6382.1-2007)
For more, please visit the website:http://www.hu-steel.com/news355_320.html
2016年7月28日星期四
Defects of Electric Resistance Welding
Defects of electric resistance welding is following below:
1) There is a lack of a reliable method for non-destructive testing, welding quality only by destructive testing process to check specimens and artifacts, as well as by a variety of monitoring techniques to ensure that.
2) Points, seam welded lap joint not only increases the weight of the structure, and because between the two plates around the nugget form an angle, resulting in a lower tensile strength and fatigue strength of the joint.
3) Power equipment, high degree of mechanization and automation, so that the higher cost of equipment, maintenance more difficult, and the commonly used high-power single-phase AC welder is not conducive to the normal operation of the
grid. With the development of electrode wear aerospace, electronics, automobiles, household appliances and other industries, the electric resistance welded together by the society, at the same time, the quality of resistance welding also
put forward higher requirements.
1) There is a lack of a reliable method for non-destructive testing, welding quality only by destructive testing process to check specimens and artifacts, as well as by a variety of monitoring techniques to ensure that.
2) Points, seam welded lap joint not only increases the weight of the structure, and because between the two plates around the nugget form an angle, resulting in a lower tensile strength and fatigue strength of the joint.
3) Power equipment, high degree of mechanization and automation, so that the higher cost of equipment, maintenance more difficult, and the commonly used high-power single-phase AC welder is not conducive to the normal operation of the
grid. With the development of electrode wear aerospace, electronics, automobiles, household appliances and other industries, the electric resistance welded together by the society, at the same time, the quality of resistance welding also
put forward higher requirements.
SMLS or ERW
Seamless tube compared with straight seam resistance steel tube is as follows:
1, High dimensional accuracy
Diameter and wall thickness deviation, straight seam electric resistance welded pipe smaller than seamless steel tubes. This is because the steel rolling and pipe molding is easy to control, so the high dimensional accuracy.
2, Good mechanical properties
Because straight seam resistance welding steel pipes easy to carry out controlled rolling, heat treatment and welding technology with the development of technology. Weld properties can be controlled. Elongation of straight seam resistance welding pipe is higher 8% -10% than seamless tube, which is mainly carbon ratio of straight seam electric resistance welded steel pipe less about 1/2 than seamless tube.
3, Anti-ulcer ability squeeze
High concentricity straight seam resistance welding pipe wall thickness uniformity. Weld heat treatment, metal homogeneous, and therefore have a higher resistance to collapse collapse capability.
1, High dimensional accuracy
Diameter and wall thickness deviation, straight seam electric resistance welded pipe smaller than seamless steel tubes. This is because the steel rolling and pipe molding is easy to control, so the high dimensional accuracy.
2, Good mechanical properties
Because straight seam resistance welding steel pipes easy to carry out controlled rolling, heat treatment and welding technology with the development of technology. Weld properties can be controlled. Elongation of straight seam resistance welding pipe is higher 8% -10% than seamless tube, which is mainly carbon ratio of straight seam electric resistance welded steel pipe less about 1/2 than seamless tube.
3, Anti-ulcer ability squeeze
High concentricity straight seam resistance welding pipe wall thickness uniformity. Weld heat treatment, metal homogeneous, and therefore have a higher resistance to collapse collapse capability.
Disadvantages of Galvanized Mild Steel
Disadvantages of galvanized mild steel has following aspects:
On the surface of hot dip galvanized steel rice distribution classes of small dots, called zinc particles is customary. Defective zinc particles can be divided into two: one is up and down the strip surface adhesion lot of granular, strip local increase in the thickness of the zinc layer, causing the surface rough, unsightly and harmful use of known zinc particles. There are two forms, one of the larger particles of zinc tablets, the main ingredient is iron - zinc compound, which is the end of slag.
When coated galvanized steel edge is much higher than the middle of coating thickness, edge thickness is produced.
When the air knife nozzle clogging occurs locally when in a position corresponding to the strip will produce thick zinc layer is formed with marks.
In the middle of the strip edge or rendered bright stripes or the presence of dendritic conchoidal crystal crystalline zinc this particular often make local zinc layer projections, it is called zinc projections.
Strip out from uncoiler to galvanized defects between coiler, strip and a mechanical relative movement generated.
On the surface of hot dip galvanized steel rice distribution classes of small dots, called zinc particles is customary. Defective zinc particles can be divided into two: one is up and down the strip surface adhesion lot of granular, strip local increase in the thickness of the zinc layer, causing the surface rough, unsightly and harmful use of known zinc particles. There are two forms, one of the larger particles of zinc tablets, the main ingredient is iron - zinc compound, which is the end of slag.
When coated galvanized steel edge is much higher than the middle of coating thickness, edge thickness is produced.
When the air knife nozzle clogging occurs locally when in a position corresponding to the strip will produce thick zinc layer is formed with marks.
In the middle of the strip edge or rendered bright stripes or the presence of dendritic conchoidal crystal crystalline zinc this particular often make local zinc layer projections, it is called zinc projections.
Strip out from uncoiler to galvanized defects between coiler, strip and a mechanical relative movement generated.
Steel Thermal Expansion Coefficient
Steel thermal expansion coefficient αL.definition: the temperature rises 1 ℃, the relative elongation of objects.
Thermal expansion coefficient is not constant, but varies slightly with temperature, with increasing temperature.
Original length L1, L2 of the size warmed, ΔL is the amount of deformation (L2-L1) T1 is the original temperature, T2 is the temperature of the warmed, ΔT is the temperature difference (T2-T1)
Body temperature changes due to swelling phenomenon occurs called "thermal expansion." Usually refers to external pressure under the same circumstances, most of the material at elevated temperatures, its volume increases, the temperature is lowered the volume is reduced. Under the same conditions, the maximum expansion of the gas, followed by expansion of the liquid, solid minimal swelling. A small number of substances in a certain temperature range, the temperature rises, but its volume is reduced. Because the body temperature, the average kinetic energy of the molecular motion increases, the distance between molecules increases, consequent expansion of volume of the object; temperature decreases, the average kinetic energy of the object when the cooling becomes small molecules, intermolecular distance is shortened, so the volume of the object will shrink. Also, because the average kinetic energy of the different size of the solid, liquid and gaseous molecular motion, and thus the thermal expansion of the macroscopic phenomena from the point of view also significant differences.
Thermal expansion coefficient is not constant, but varies slightly with temperature, with increasing temperature.
Original length L1, L2 of the size warmed, ΔL is the amount of deformation (L2-L1) T1 is the original temperature, T2 is the temperature of the warmed, ΔT is the temperature difference (T2-T1)
Body temperature changes due to swelling phenomenon occurs called "thermal expansion." Usually refers to external pressure under the same circumstances, most of the material at elevated temperatures, its volume increases, the temperature is lowered the volume is reduced. Under the same conditions, the maximum expansion of the gas, followed by expansion of the liquid, solid minimal swelling. A small number of substances in a certain temperature range, the temperature rises, but its volume is reduced. Because the body temperature, the average kinetic energy of the molecular motion increases, the distance between molecules increases, consequent expansion of volume of the object; temperature decreases, the average kinetic energy of the object when the cooling becomes small molecules, intermolecular distance is shortened, so the volume of the object will shrink. Also, because the average kinetic energy of the different size of the solid, liquid and gaseous molecular motion, and thus the thermal expansion of the macroscopic phenomena from the point of view also significant differences.
2016年7月26日星期二
Hot-rolled Tubing Coupling Tube Development
Oil and gas drilling steel pipe, including drill pipe, casing and tubing, the special nature of oil and gas exploitation, working conditions extremely complex conditions can be quite harsh, so its very strict quality requirements. Such as tubing in the course of not only bear the weight of the column itself, the need to withstand corrosion oil (gas), water, acids, etc., and thus their shape, size, coupling strength, tightness, mechanical properties and corrosion resistance and so on there are strict requirements. Tubing Coupling by threaded connection tubing, to bear the weight, and thus their higher. The coupling blanks for the manufacture of tubing coupling short pipe coupling tube.
Grade J55 tubing pipe coupling process is as follows:
Tube - blanking - heating - heat-centering - piercing - wear mandrel - necking - jacking - loose stick - stick off (after the mandrel lubrication, before sending necking machine, recycling) - hot saw - reheating - high pressure water descaling - tension reducing - cooling bed Cooling - cold saws - straightening - product testing - packaging and storage.
High quality round tube rolling rolling through the refining process, according to the requirements of API Spec 5CT, finished normalizing the status of delivery; when the hot-rolled tubes finishing temperature not lower than the normalizing temperature, can replace normalizing.
Grade J55 tubing pipe coupling process is as follows:
Tube - blanking - heating - heat-centering - piercing - wear mandrel - necking - jacking - loose stick - stick off (after the mandrel lubrication, before sending necking machine, recycling) - hot saw - reheating - high pressure water descaling - tension reducing - cooling bed Cooling - cold saws - straightening - product testing - packaging and storage.
High quality round tube rolling rolling through the refining process, according to the requirements of API Spec 5CT, finished normalizing the status of delivery; when the hot-rolled tubes finishing temperature not lower than the normalizing temperature, can replace normalizing.
Pipe Surface Roughness
Pipe surface roughness is the machining surface having a smaller pitch and the tiny valley irregularities. The distance between two peaks or two troughs (the pitch) is small (less than 1mm), it is difficult to distinguish with the naked eye, so it belongs to the microstructure geometry errors. Surface roughness is, the more smooth the surface. The surface roughness of size, have a great impact on the performance of mechanical parts.
Pipe surface roughness mainly in the following aspects:
1) Pipe surface roughness of the parts wear resistance. The rougher the surface, the smaller the effective contact area between the mating surfaces, the greater the pressure, the faster the wear.
2) Pipe surface roughness of stability of the complex nature. For clearance fit, the rougher the surface, the more easy to wear, so that the gap increases during operation; interference fit, because the assembly will squeeze microscopic convex peak level, reducing the actual effective interference, reduce the coupling strength.
3) Pipe surface roughness of fatigue strength of parts. There is a big part of the surface roughness of the trough, they are like sharp corners, as gaps and cracks, is very sensitive to stress concentration, thus affecting the fatigue strength of parts.
4) Pipe surface roughness of parts corrosion resistance. Rough surface, easy to make corrosive gas or liquid to penetrate through the surface of microscopic metal inner valley, causing surface erosion.
5) Pipe surface roughness of the parts of the seal. Unable tight fit between the rough surface, gas or liquid leakage gap between the contact surfaces through.
6) Contact stiffness and surface roughness of the parts. Part bonding surface contact stiffness is in the external force, the contact resistance to deformation. Rigidity of the machine depends largely on the contact stiffness between the various parts.
7) Affect the measurement accuracy of parts. Part measured surface and measuring tool to measure the surface roughness of the surface will directly affect the accuracy of measurement, especially in precision measurement. Further, the surface roughness of the parts plated coatings, thermal conductivity and contact resistance, reflectivity and radiation performance, liquid and gas flow resistance, the flow of current in the conductor surface so there will be different degrees of impact.
Pipe surface roughness mainly in the following aspects:
1) Pipe surface roughness of the parts wear resistance. The rougher the surface, the smaller the effective contact area between the mating surfaces, the greater the pressure, the faster the wear.
2) Pipe surface roughness of stability of the complex nature. For clearance fit, the rougher the surface, the more easy to wear, so that the gap increases during operation; interference fit, because the assembly will squeeze microscopic convex peak level, reducing the actual effective interference, reduce the coupling strength.
3) Pipe surface roughness of fatigue strength of parts. There is a big part of the surface roughness of the trough, they are like sharp corners, as gaps and cracks, is very sensitive to stress concentration, thus affecting the fatigue strength of parts.
4) Pipe surface roughness of parts corrosion resistance. Rough surface, easy to make corrosive gas or liquid to penetrate through the surface of microscopic metal inner valley, causing surface erosion.
5) Pipe surface roughness of the parts of the seal. Unable tight fit between the rough surface, gas or liquid leakage gap between the contact surfaces through.
6) Contact stiffness and surface roughness of the parts. Part bonding surface contact stiffness is in the external force, the contact resistance to deformation. Rigidity of the machine depends largely on the contact stiffness between the various parts.
7) Affect the measurement accuracy of parts. Part measured surface and measuring tool to measure the surface roughness of the surface will directly affect the accuracy of measurement, especially in precision measurement. Further, the surface roughness of the parts plated coatings, thermal conductivity and contact resistance, reflectivity and radiation performance, liquid and gas flow resistance, the flow of current in the conductor surface so there will be different degrees of impact.
The Pipe-line Detection of Welded Steel Pipe
Welded steel pipe at the factory to go through rigorous testing to ensure the quality of welded compliance standards and user requirements. Pipe inspection items generally include: appearance quality factory inspection project, straightness, dimensions, and other types of weld quality inspection items (flattening, flaring, bending, etc.). Welded pipe surface quality and straightness inspection by a full-time quality inspector confirmed finishing process pipe segment using visual way, the implementation of the detection test dimensions available random sampling method, and the weld quality inspection shall be made on special equipment by root on line. This article focuses on online testing of the weld. At present, about our national standards, testing methods available weld pipe hydrostatic testing, ultrasonic testing, eddy current testing in any way.
Hydrostatic test is the most common, the most direct and reliable weld line inspection
Measured way, in a variety of hydraulic test machine. When the pressure test, through the first low-pressure water, filled the whole steel pipe to make the air side by side, and then to test pressure specified by the pressurized way, and to stabilize the prescribed time, when there is no pipe welds and around wet, spray, leakage or permanent deformation is considered qualified.
When the metal by an alternating magnetic field is induced metal surface
Eddy currents; when the presence of the metal surface defects, since the impedance increases, the eddy current value becomes smaller; and when no defect of a metallic material, the value of the stable vortex; size of the power according to the eddy current loss, can be characterized metals whether the surface defects.
Ultrasonic wave propagation in the process, will have a reflection on the media surface.
If there is a crack pipe welds, weld, false welding, lap welding defects such as acoustic impedance will change significantly, so that ultrasonic generating different reflection, through a dedicated instrument will be identified to achieve the purpose of flaw detection. The main steel tube ultrasonic flaw detection are: rotating the probe, steel straight forward; probe fixed, steel rotating forward; steel rotating probe straight forward three forms, in the production of different pipe diameter in both applications.
Hydrostatic test is the most common, the most direct and reliable weld line inspection
Measured way, in a variety of hydraulic test machine. When the pressure test, through the first low-pressure water, filled the whole steel pipe to make the air side by side, and then to test pressure specified by the pressurized way, and to stabilize the prescribed time, when there is no pipe welds and around wet, spray, leakage or permanent deformation is considered qualified.
When the metal by an alternating magnetic field is induced metal surface
Eddy currents; when the presence of the metal surface defects, since the impedance increases, the eddy current value becomes smaller; and when no defect of a metallic material, the value of the stable vortex; size of the power according to the eddy current loss, can be characterized metals whether the surface defects.
Ultrasonic wave propagation in the process, will have a reflection on the media surface.
If there is a crack pipe welds, weld, false welding, lap welding defects such as acoustic impedance will change significantly, so that ultrasonic generating different reflection, through a dedicated instrument will be identified to achieve the purpose of flaw detection. The main steel tube ultrasonic flaw detection are: rotating the probe, steel straight forward; probe fixed, steel rotating forward; steel rotating probe straight forward three forms, in the production of different pipe diameter in both applications.
Hot Extruded Seamless Steel Pipe
Hot extrusion billet of seamless steel pipe can be forged billet, rolled billet, slab, billet centrifugal casting and so on. Short or long blank blank in the machine shop after peeling, sawing, drilling deep holes, after turning face and chamfering into the extrusion line.
Processed through the blank into the first washing machine for degreasing treatment before the annular heating furnace, and then into the annular heating furnace. Generally annular blank in a furnace heated to less than 900 ℃. But it can be heated directly to the hot steel extrusion temperature (for reaming without direct extrusion billet) according to process requirements. Then go to the vertical induction furnace for heating the material to the hot extrusion temperature. After heating the blank in a good dusting the outer bench painted a good glass frit, by the robot into the blank punch (expanded) in the cylinder bore, the glass powder is added after the blank ends of the "bell". Then, in legislation were red (expanded) hole piercing machine. After punching (expansion) of the hollow billet and the mold holes after exposure arising due to the temperature drop should be namely reheating heat up, but the impact of the glass frit billet surface reheating temperature detection, so that the heating temperature deviation, it is generally in to be reheated before removal, to remove the surface of the glass film blank, and then heated and the heated billet through the inner and outer surface of the rear glass powder coated by the ingot is fed into an extruder for the center for extrusion. After the completion of extrusion products and the press are separated by more than separating saws. Products and tools need to be appropriate cold treatment.
As we all know, hot extrusion cylinder for the interference multilayer tube fitted together, the amount of interference in the rational design, processing size in line with the premise of the drawings, the first warm-up before use, regular cleaning of the inner wall of the glass frit, and check the inner wall scratches under the circumstances, the general life in 5000 to 10 000 or more. Extrusion die with the longest contact time of the hot metal in the extrusion process, the life of a relative minimum. For the extrusion die longer life, general requirements, where possible squeeze faster, shorter cutting separation, to reduce the hot metal in the extrusion die residence time and extrusion die each should be checked and treated after extrusion, not only to ensure product quality, but also improve the extrusion die life. Since the piercing needle breaking small area when wrapped in hot metal extrusion, rapid temperature rise caused by the decline in the mechanical properties, it is necessary to provide sufficient cooling. Foreign steel extruder designed with internal cooling system is designed punch pin, but the effect is more general look. For the small size of the needle piercing cold hole greatly reduced the strength of the punch pin, it could easily lead to back needle hour break, while the large size of the piercing needle in terms of the cooling rate is too slow. Tunze company in the design 36MN stainless steel extruder, taking into account the small and medium size objects product products than it is not designed in the cooling system, but the design of a special cooling device for piercing needle piercing needle after the completion of the outer extrusion cold, and achieved good results, so that the service life of the punch pin from 10 to 30 times to more than 100 times, greatly improving the life of the punch pin.
Processed through the blank into the first washing machine for degreasing treatment before the annular heating furnace, and then into the annular heating furnace. Generally annular blank in a furnace heated to less than 900 ℃. But it can be heated directly to the hot steel extrusion temperature (for reaming without direct extrusion billet) according to process requirements. Then go to the vertical induction furnace for heating the material to the hot extrusion temperature. After heating the blank in a good dusting the outer bench painted a good glass frit, by the robot into the blank punch (expanded) in the cylinder bore, the glass powder is added after the blank ends of the "bell". Then, in legislation were red (expanded) hole piercing machine. After punching (expansion) of the hollow billet and the mold holes after exposure arising due to the temperature drop should be namely reheating heat up, but the impact of the glass frit billet surface reheating temperature detection, so that the heating temperature deviation, it is generally in to be reheated before removal, to remove the surface of the glass film blank, and then heated and the heated billet through the inner and outer surface of the rear glass powder coated by the ingot is fed into an extruder for the center for extrusion. After the completion of extrusion products and the press are separated by more than separating saws. Products and tools need to be appropriate cold treatment.
As we all know, hot extrusion cylinder for the interference multilayer tube fitted together, the amount of interference in the rational design, processing size in line with the premise of the drawings, the first warm-up before use, regular cleaning of the inner wall of the glass frit, and check the inner wall scratches under the circumstances, the general life in 5000 to 10 000 or more. Extrusion die with the longest contact time of the hot metal in the extrusion process, the life of a relative minimum. For the extrusion die longer life, general requirements, where possible squeeze faster, shorter cutting separation, to reduce the hot metal in the extrusion die residence time and extrusion die each should be checked and treated after extrusion, not only to ensure product quality, but also improve the extrusion die life. Since the piercing needle breaking small area when wrapped in hot metal extrusion, rapid temperature rise caused by the decline in the mechanical properties, it is necessary to provide sufficient cooling. Foreign steel extruder designed with internal cooling system is designed punch pin, but the effect is more general look. For the small size of the needle piercing cold hole greatly reduced the strength of the punch pin, it could easily lead to back needle hour break, while the large size of the piercing needle in terms of the cooling rate is too slow. Tunze company in the design 36MN stainless steel extruder, taking into account the small and medium size objects product products than it is not designed in the cooling system, but the design of a special cooling device for piercing needle piercing needle after the completion of the outer extrusion cold, and achieved good results, so that the service life of the punch pin from 10 to 30 times to more than 100 times, greatly improving the life of the punch pin.
2016年7月25日星期一
Advantages of Hot Rolling
1. Hot-rolled can significantly reduce consumption, reduce costs
Where it can be hot-rolled billet should be hot-rolled metal, because metal hot deformation resistance than cold-rolled low, can significantly reduce energy consumption during rolling.
2. The hot rolling process can improve the performance of metals and alloys
Because coarse grains of hot-rolled state can cast broken, microcracks healing and reduce or eliminate casting defects, converting low ductility cast structure into a higher plastic deformation of tissue.
3. The hot rolling may be a large reduction rolling
Within a certain temperature range, with increasing temperature, increasing the plasticity of metals, can use a larger amount of deformation of rolling, it can also reduce metal crack defects, improving the rate of finished metal.
4. The hot rolling usually large ingot rolling
Since the hot-rolled metal has high plasticity and less distortion resistance. It may be larger ingots, both to improve productivity, yield and rolling speed, but also for the continuous rolling process automation to create the conditions.
For more, please visit: http://www.hunanpipe.com/news357_658.html
Where it can be hot-rolled billet should be hot-rolled metal, because metal hot deformation resistance than cold-rolled low, can significantly reduce energy consumption during rolling.
2. The hot rolling process can improve the performance of metals and alloys
Because coarse grains of hot-rolled state can cast broken, microcracks healing and reduce or eliminate casting defects, converting low ductility cast structure into a higher plastic deformation of tissue.
3. The hot rolling may be a large reduction rolling
Within a certain temperature range, with increasing temperature, increasing the plasticity of metals, can use a larger amount of deformation of rolling, it can also reduce metal crack defects, improving the rate of finished metal.
4. The hot rolling usually large ingot rolling
Since the hot-rolled metal has high plasticity and less distortion resistance. It may be larger ingots, both to improve productivity, yield and rolling speed, but also for the continuous rolling process automation to create the conditions.
For more, please visit: http://www.hunanpipe.com/news357_658.html
Seam and Seamless Pipe
Seam and seamless pipe difference
Concentricity: seamless manufacturing process at a temperature of 2200 °f punched a hole in the stainless steel billet, and at this temperature, tool steel becomes soft and stamped and drawing a spiral shape from Kong Zhongcheng come out. Such non-uniform wall thickness of the pipe and eccentric high. Thus astm allow seamless tube wall thickness difference than to have a large difference in the thickness of the pipe joints. Pipe joints is (4-5 feet per roll width) made by precision cold-rolled sheet. Cold-rolled sheet is usually the biggest difference between the wall thickness of 0.002 inches. Steel plate was cut into a width of πd, where d is the outer diameter of the pipe. Slit pipe wall thickness tolerance is small, and the entire circumference of the wall thickness is very uniform.
Welding performance: general chemical composition of seamless pipe and tube joints have some differences. Production of seamless steel components simply meet the basic requirements of astm. It produced the steel pipe joints contain chemicals suitable for welding. Such as silicon, sulfur, manganese, oxygen, and other elements of the triangle ferrite produces an easily transferring heat weld material during the welding process by mixing a certain proportion, so that the entire weld penetration. Missing more than the chemical composition of the steel pipe, seamless pipe, for example, the welding process will produce a variety of uncertainties, not easy to weld and solder impervious.
Grain size: typically, the metal grain size and heat treatment temperature and time to maintain the same temperature related. Thus, annealed and slit pipe seamless grain size are the same. If the pipe joints with a minimum of cold treatment, the weld on the grain size is smaller than the grain size of the weld metal, otherwise, the grain size is the same.
Strength: the strength of the pipeline depends on the alloy composition, which contains the same alloy and heat treatment of the same seamless and seamed pipes essentially uniform intensity. After tensile tests and three-dimensional vibration testing, pipe joints tear occurs almost exclusively in the area away from the welding point or heat the place. This is because the weld fewer impurities and the nitrogen content is higher, and thus the strength of the weld is better than the other region. However asme boiler and pressure vessel Association believes pipe joints can only bear 85% of the allowable pressure, mainly due to the collection of data as early as from the improved welding equipment in use today. asme provisions by 100% ultrasonic testing pipe joints are fully licensed to withstand pressure. Similarly, Europe and Asia also provides through the slit pipe eddy current testing can ensure quality, eddy current testing is required by legal procedures and permit its institutions were weldability. trent's eddy current testing by the Swedish licensing power section. asme think current loss is based on a smaller pipe joints high performance.
Corrosion resistance: resistance to corrosion is good or bad depends on the composition of the alloy of the same. The same chemical composition of seamless pipe and heat treatment have been completely slit pipe corrosion resistance is consistent. Supplementary test astm provide proof weld corrosion resistance equivalent to or better than the metal being welded. Under acidic chloride environments, incomplete heat treatment at a seam welded pipe corrosion will accelerate, but this is only required corrosion tests, in fact, the environment is not so bad. Bending and stretching properties: extension of the weld may be prescribed following tests to verify through astm: bent 45 °, then bent to 90 °, and then along the weld flattening; then turn around pipe joints to repeat the steps above to the weld curved inner diameter reaches 180 °. Weld quality standard is adopted at a magnification of 40 times between the situation allowed to tear or separation of the grain. Pipeline bend radius is controlled by the composition of the alloy, the general minimum bend radius 2d. Seam welding conditions are ideal in a neutral or compression. Further, the pipe should be annealed to reduce its hardness, thereby improving the bending performance.
Concentricity: seamless manufacturing process at a temperature of 2200 °f punched a hole in the stainless steel billet, and at this temperature, tool steel becomes soft and stamped and drawing a spiral shape from Kong Zhongcheng come out. Such non-uniform wall thickness of the pipe and eccentric high. Thus astm allow seamless tube wall thickness difference than to have a large difference in the thickness of the pipe joints. Pipe joints is (4-5 feet per roll width) made by precision cold-rolled sheet. Cold-rolled sheet is usually the biggest difference between the wall thickness of 0.002 inches. Steel plate was cut into a width of πd, where d is the outer diameter of the pipe. Slit pipe wall thickness tolerance is small, and the entire circumference of the wall thickness is very uniform.
Welding performance: general chemical composition of seamless pipe and tube joints have some differences. Production of seamless steel components simply meet the basic requirements of astm. It produced the steel pipe joints contain chemicals suitable for welding. Such as silicon, sulfur, manganese, oxygen, and other elements of the triangle ferrite produces an easily transferring heat weld material during the welding process by mixing a certain proportion, so that the entire weld penetration. Missing more than the chemical composition of the steel pipe, seamless pipe, for example, the welding process will produce a variety of uncertainties, not easy to weld and solder impervious.
Grain size: typically, the metal grain size and heat treatment temperature and time to maintain the same temperature related. Thus, annealed and slit pipe seamless grain size are the same. If the pipe joints with a minimum of cold treatment, the weld on the grain size is smaller than the grain size of the weld metal, otherwise, the grain size is the same.
Strength: the strength of the pipeline depends on the alloy composition, which contains the same alloy and heat treatment of the same seamless and seamed pipes essentially uniform intensity. After tensile tests and three-dimensional vibration testing, pipe joints tear occurs almost exclusively in the area away from the welding point or heat the place. This is because the weld fewer impurities and the nitrogen content is higher, and thus the strength of the weld is better than the other region. However asme boiler and pressure vessel Association believes pipe joints can only bear 85% of the allowable pressure, mainly due to the collection of data as early as from the improved welding equipment in use today. asme provisions by 100% ultrasonic testing pipe joints are fully licensed to withstand pressure. Similarly, Europe and Asia also provides through the slit pipe eddy current testing can ensure quality, eddy current testing is required by legal procedures and permit its institutions were weldability. trent's eddy current testing by the Swedish licensing power section. asme think current loss is based on a smaller pipe joints high performance.
Corrosion resistance: resistance to corrosion is good or bad depends on the composition of the alloy of the same. The same chemical composition of seamless pipe and heat treatment have been completely slit pipe corrosion resistance is consistent. Supplementary test astm provide proof weld corrosion resistance equivalent to or better than the metal being welded. Under acidic chloride environments, incomplete heat treatment at a seam welded pipe corrosion will accelerate, but this is only required corrosion tests, in fact, the environment is not so bad. Bending and stretching properties: extension of the weld may be prescribed following tests to verify through astm: bent 45 °, then bent to 90 °, and then along the weld flattening; then turn around pipe joints to repeat the steps above to the weld curved inner diameter reaches 180 °. Weld quality standard is adopted at a magnification of 40 times between the situation allowed to tear or separation of the grain. Pipeline bend radius is controlled by the composition of the alloy, the general minimum bend radius 2d. Seam welding conditions are ideal in a neutral or compression. Further, the pipe should be annealed to reduce its hardness, thereby improving the bending performance.
2016年7月21日星期四
Advantages and Disadvantages of Pipeline Transportation
Pipeline transportation with the growth in oil and gas production and developed, has become the main mode of transport onshore oil and gas transport pipeline in recent years, solid materials, such as coal, ore pipeline transport, is also a great the development of pipeline transport advantages are: (1) transport capacity, a foreign coal pipeline diameter 720 mm, and a year to transport 20 million tons of coal, equivalent to almost one-directional transmission capacity of a single-track railway; (2) small amount of traffic engineering, small footprint, pipeline transportation just laying pipelines, construction of pumping stations, construction of railways is much smaller than the earthwork and the plains are mostly buried under, does not occupy farmland; (3) energy consumption in various modes of transport is the lowest; (4) safe, reliable, non-polluting, low cost; (5) the climate, and all-weather transport, high reliability and delivery of goods (6) pipeline can take shortcuts., short distance transport; (7) can be closed transport, less wear and tear.
The disadvantage of pipeline transportation are: (1) specific and strong, can only transport oil, natural gas and solid slurry (such as coal), but in the field it occupies, with a fixed and reliable market; (2) pipeline from input the magnitude of the amount of the highest traffic among small, so in the early field development, the use of pipeline transportation difficulties, but also to road, rail, sea and land transportation as a transition. (3) the construction of pipelines, gas stations and oil storage device has to spend huge investment. In addition, the pipeline route through a set dressing, unregulated traffic room, small transport elasticity, flexibility is poor.
The disadvantage of pipeline transportation are: (1) specific and strong, can only transport oil, natural gas and solid slurry (such as coal), but in the field it occupies, with a fixed and reliable market; (2) pipeline from input the magnitude of the amount of the highest traffic among small, so in the early field development, the use of pipeline transportation difficulties, but also to road, rail, sea and land transportation as a transition. (3) the construction of pipelines, gas stations and oil storage device has to spend huge investment. In addition, the pipeline route through a set dressing, unregulated traffic room, small transport elasticity, flexibility is poor.
MS and GI Pipe Difference
Galvanized iron pipes commonly used on water pipe lines, it is dipped into zinc for corrosion protection
GI Pipe is “Galvanized Iron” Pipe. Material ms is mild steel and gi is galvanized steel that has been hot dipped .These days the pipe will likely be made from steel rather than iron.
galvanized iron pipes commonly used on water pipe lines.
Mild steel is untreated and usually hot or cold rolled or in the case of pipe extruded while molten. Low carbon content and rusts in humid weather and can be bent easier than other steel. Its not black pipe used for gas, its not case hardened with cyanide, its not galvanized with zinc plating, its not blued like used for guns, its not cast like for cast iron furniture. Its the most affordable type of steel.
Mild steel pipe refers to the content of less than 0.25% carbon steel because of its low strength, low hardness and soft. It includes most of the part of ordinary carbon steel and high-quality carbon structural steel, mostly without heat treatment used in engineering structures, some carburizing heat treatment and other mechanical parts required for wear.
For more, please visit webiste:http://www.hu-steel.com/news355_313.html
GI Pipe is “Galvanized Iron” Pipe. Material ms is mild steel and gi is galvanized steel that has been hot dipped .These days the pipe will likely be made from steel rather than iron.
galvanized iron pipes commonly used on water pipe lines.
Mild steel is untreated and usually hot or cold rolled or in the case of pipe extruded while molten. Low carbon content and rusts in humid weather and can be bent easier than other steel. Its not black pipe used for gas, its not case hardened with cyanide, its not galvanized with zinc plating, its not blued like used for guns, its not cast like for cast iron furniture. Its the most affordable type of steel.
Mild steel pipe refers to the content of less than 0.25% carbon steel because of its low strength, low hardness and soft. It includes most of the part of ordinary carbon steel and high-quality carbon structural steel, mostly without heat treatment used in engineering structures, some carburizing heat treatment and other mechanical parts required for wear.
For more, please visit webiste:http://www.hu-steel.com/news355_313.html
2016年7月20日星期三
Types of ERW Welding
Types of erw welding are following below:
Spot welding
Spot welding (Spot Welding) welding member is assembled into lap joints, and pressed between two cylindrical electrodes, the use of a hot-melt resistance of the base metal, resistance welding solder joint formation. Mainly used for spot welding sheet metal welding.
Seam welding
Seam welding (Seam Welding) and spot welding process is similar, but with a disk-shaped rotating wheel columnar electrode or electrodes, the weldment assembled into lap or butt joints, and the electrodes disposed between the two rollers, the welding pressure rollers and rotating member, continuous or intermittent power transmission, resistance welding method for forming a continuous weld.
Butt
Butt (Butt Welding) is to make the weldment along the entire contact surface resistance welding method of welding.
Projection welding
Projection welding (Projection Welding) is a variant form of spot welding; on a workpiece has preformed bumps, when the projection welding, one can form one or more of the nugget at the joint.
Spot welding
Spot welding (Spot Welding) welding member is assembled into lap joints, and pressed between two cylindrical electrodes, the use of a hot-melt resistance of the base metal, resistance welding solder joint formation. Mainly used for spot welding sheet metal welding.
Seam welding
Seam welding (Seam Welding) and spot welding process is similar, but with a disk-shaped rotating wheel columnar electrode or electrodes, the weldment assembled into lap or butt joints, and the electrodes disposed between the two rollers, the welding pressure rollers and rotating member, continuous or intermittent power transmission, resistance welding method for forming a continuous weld.
Butt
Butt (Butt Welding) is to make the weldment along the entire contact surface resistance welding method of welding.
Projection welding
Projection welding (Projection Welding) is a variant form of spot welding; on a workpiece has preformed bumps, when the projection welding, one can form one or more of the nugget at the joint.
Straightening Machine on Which Princple
Straightening machine is metal profiles, bars, tubes, wire, etc. straightening equipment. Straightening roll straightening machine by pressing on the bars and so it changes straightness. Usually there are two rows of straightening rollers, varying amounts. There are also two roll straightener, relying on two roll angle (intermediate concave hyperbolic rolls) material changes in different diameters straightening. The main types of pressure straightening machine, balancing roller straightening machine, shoe roll straightening, rotating anti-leveler and so on.
Straightening machine on which princple
Roller position with the movement direction an angle straightening products, two or three large active pressure roller, driven by a motor for rotation in the same direction, on the other side of a number of small rolls are driven pressure rollers which It is relying on the rotating rod or tube to be rotated by the frictional force. In order to achieve compression roller products required, these small rollers may be simultaneously or separately adjust the forward or backward position, the more general the number of rollers, the higher the precision straightening products. After the article is roll bite, we continue to make linear or rotary motion, thus making all aspects of the product to withstand compression, bending, flattening and other deformation, and finally achieve the purpose of straightening.
Practice of straightening machine
⒈ before boot, check the hydraulic station hydraulic oil, gear box, gear box gear oil if fills.
⒉ before the main motor starts, examine and adjust the angle and carry out the hydraulic system pressure adjustment.
⒊ lubricant injection lubrication points, check the operation status of the mechanical transmission part to make it flexible transport means.
⒋ operator Wear PPE, shall undergo boot, string Kong.
⒌ after oil, hydraulic oil pressure became stable, the straightening rollers lift to the initial position.
⒍ by artificial feeding, fed through the steel pipe straightening roller straightening roller for the third clamping pressure.
⒎ start the main motor, steel rotating forward while being straightened.
⒏ motor stops, stop straightening straightening roller, straightening roller lift, straightening sent pipe.
⒐ to reverse the straightening can be reversed by operating the stage knob so that the host reversal, reverse straightening.
⒑ main motor is stopped, stop straightening roller straightening steel pipe is returned to the starting position, repeat until the next program instruction straightening.
After ⒒ down, shut the mains and can not change the program controller.
Straightening machine on which princple
Roller position with the movement direction an angle straightening products, two or three large active pressure roller, driven by a motor for rotation in the same direction, on the other side of a number of small rolls are driven pressure rollers which It is relying on the rotating rod or tube to be rotated by the frictional force. In order to achieve compression roller products required, these small rollers may be simultaneously or separately adjust the forward or backward position, the more general the number of rollers, the higher the precision straightening products. After the article is roll bite, we continue to make linear or rotary motion, thus making all aspects of the product to withstand compression, bending, flattening and other deformation, and finally achieve the purpose of straightening.
Practice of straightening machine
⒈ before boot, check the hydraulic station hydraulic oil, gear box, gear box gear oil if fills.
⒉ before the main motor starts, examine and adjust the angle and carry out the hydraulic system pressure adjustment.
⒊ lubricant injection lubrication points, check the operation status of the mechanical transmission part to make it flexible transport means.
⒋ operator Wear PPE, shall undergo boot, string Kong.
⒌ after oil, hydraulic oil pressure became stable, the straightening rollers lift to the initial position.
⒍ by artificial feeding, fed through the steel pipe straightening roller straightening roller for the third clamping pressure.
⒎ start the main motor, steel rotating forward while being straightened.
⒏ motor stops, stop straightening straightening roller, straightening roller lift, straightening sent pipe.
⒐ to reverse the straightening can be reversed by operating the stage knob so that the host reversal, reverse straightening.
⒑ main motor is stopped, stop straightening roller straightening steel pipe is returned to the starting position, repeat until the next program instruction straightening.
After ⒒ down, shut the mains and can not change the program controller.
2016年7月19日星期二
Features of Eddy Current Testing
From the principle of eddy currents can be seen in eddy current testing has the following characteristics:
(1) Eddy current testing is only applicable to the conductive material, if a non-conductive material, it can not induce a swirling current, it can not make use of eddy current testing.
(2) Eddy current testing is particularly suitable for detection of surface and near-surface conductive material.
(3) Eddy current testing does not need coupling agent. Electromagnetic Field in Eddy Current Testing substance is excited by an electromagnetic wave and particle nature are volatile, so between the probe (coil) can be coupled with the workpiece without having to spread, it can be non-contact detection. This is better than ultrasonic testing. Because ultrasound is a mechanical wave, can only propagate in the substance. So ultrasonic inspection coupling agent must be added between the probe and the workpiece.
(4) Eddy current testing for fast and automated testing.
(5) Eddy current testing can be applied to the detection of the high temperature metal, because the metal having conductivity at high temperatures.
(6) Eddy current testing is also suitable for detecting shaped material, as long as the coil into various shapes can be detected.
(1) Eddy current testing is only applicable to the conductive material, if a non-conductive material, it can not induce a swirling current, it can not make use of eddy current testing.
(2) Eddy current testing is particularly suitable for detection of surface and near-surface conductive material.
(3) Eddy current testing does not need coupling agent. Electromagnetic Field in Eddy Current Testing substance is excited by an electromagnetic wave and particle nature are volatile, so between the probe (coil) can be coupled with the workpiece without having to spread, it can be non-contact detection. This is better than ultrasonic testing. Because ultrasound is a mechanical wave, can only propagate in the substance. So ultrasonic inspection coupling agent must be added between the probe and the workpiece.
(4) Eddy current testing for fast and automated testing.
(5) Eddy current testing can be applied to the detection of the high temperature metal, because the metal having conductivity at high temperatures.
(6) Eddy current testing is also suitable for detecting shaped material, as long as the coil into various shapes can be detected.
Characteristics of galvanized steel welding
Characteristics of galvanized steel welding
Galvanized steel is generally low carbon steel plated with zinc, the zinc coating is generally 20um thick. At 419 ° C, the boiling point of about 908 ° C melting point of zinc. In welding, the melted liquid zinc bath floating on the surface or in the root of the weld location. Zinc has a greater solubility in iron, zinc etching liquid will go into the weld metal along the grain boundaries, low-melting zinc to form a "liquid metal embrittlement." Meanwhile, zinc and iron brittle intermetallic compounds can be formed, these brittle phases so that the weld metal plastic lower under tensile stress and cracks. If the fillet weld, especially the fillet weld T-joints most prone to penetrate the cracks. When welding galvanized steel, zinc layer and the surface of the groove at the edge of the arc under the action of heat, oxidation, melting, evaporation as well as volatile white smoke and steam, can easily cause weld porosity.
ZnO due to oxidation and the formation of its high melting point of about 1800 ° C or more, if small parameter in the welding process, will cause the ZnO slag, at the same time. Since Zn become deoxidizer. Produces FeO-MnO or FeO-MnO-SiO2 low melting point oxide slag. Second, due to the evaporation of zinc, volatile lot of white smoke, to stimulate the human body, harmful effects, therefore, must be welded zinc coating at the polished off.
Welding process control
Preparation before welding galvanized steel and low carbon steel is generally the same, you need to pay attention is to seriously handle the groove dimensions and the nearby zinc coating. For penetration, groove size should be appropriate, generally 60 ~ 65 °, to leave some space, usually 1.5 ~ 2.5mm; zinc in order to reduce the penetration of the weld, before welding can be galvanized inside groove Clear after layer and then welded. In practice, supervision, using a centralized playing groove, leaving blunt edge technology for centralized control, two welding process, reducing the possibility of incomplete penetration.
Galvanized pipe welding rod should be based on the choice of substrate material, usually low-carbon steel on account ease, use J422 is more common.
Welding techniques: When welding the first layer of the multilayer welding seam, try to make it melt and vaporize the zinc layer, evaporation and escape the weld, can greatly reduce the liquid zinc to remain in the weld. When fillet welds, as far as possible in the first layer to melt and vaporize the zinc coating, evaporation and escape the weld, the method is first removed from the ends of the electrode forward about 5 ~ 7mm, when the zinc layer melted down and continue to move back to the original position welding. Again when horizontal welding and vertical welding, such as welding slag, such as the choice of short-J427, undercut tends to be minimal; roundtrip transportation around if strip technology, but can be defect-free weld quality.
Galvanized steel is generally low carbon steel plated with zinc, the zinc coating is generally 20um thick. At 419 ° C, the boiling point of about 908 ° C melting point of zinc. In welding, the melted liquid zinc bath floating on the surface or in the root of the weld location. Zinc has a greater solubility in iron, zinc etching liquid will go into the weld metal along the grain boundaries, low-melting zinc to form a "liquid metal embrittlement." Meanwhile, zinc and iron brittle intermetallic compounds can be formed, these brittle phases so that the weld metal plastic lower under tensile stress and cracks. If the fillet weld, especially the fillet weld T-joints most prone to penetrate the cracks. When welding galvanized steel, zinc layer and the surface of the groove at the edge of the arc under the action of heat, oxidation, melting, evaporation as well as volatile white smoke and steam, can easily cause weld porosity.
ZnO due to oxidation and the formation of its high melting point of about 1800 ° C or more, if small parameter in the welding process, will cause the ZnO slag, at the same time. Since Zn become deoxidizer. Produces FeO-MnO or FeO-MnO-SiO2 low melting point oxide slag. Second, due to the evaporation of zinc, volatile lot of white smoke, to stimulate the human body, harmful effects, therefore, must be welded zinc coating at the polished off.
Welding process control
Preparation before welding galvanized steel and low carbon steel is generally the same, you need to pay attention is to seriously handle the groove dimensions and the nearby zinc coating. For penetration, groove size should be appropriate, generally 60 ~ 65 °, to leave some space, usually 1.5 ~ 2.5mm; zinc in order to reduce the penetration of the weld, before welding can be galvanized inside groove Clear after layer and then welded. In practice, supervision, using a centralized playing groove, leaving blunt edge technology for centralized control, two welding process, reducing the possibility of incomplete penetration.
Galvanized pipe welding rod should be based on the choice of substrate material, usually low-carbon steel on account ease, use J422 is more common.
Welding techniques: When welding the first layer of the multilayer welding seam, try to make it melt and vaporize the zinc layer, evaporation and escape the weld, can greatly reduce the liquid zinc to remain in the weld. When fillet welds, as far as possible in the first layer to melt and vaporize the zinc coating, evaporation and escape the weld, the method is first removed from the ends of the electrode forward about 5 ~ 7mm, when the zinc layer melted down and continue to move back to the original position welding. Again when horizontal welding and vertical welding, such as welding slag, such as the choice of short-J427, undercut tends to be minimal; roundtrip transportation around if strip technology, but can be defect-free weld quality.
2016年7月18日星期一
Difference between Submerged Arc Welding(SAW) and High Frequency Welding(HFW)
SAW(Submerged Arc Welding)
Submerged arc welding is an arc welding under flux layer combustion method. Welding arc between the wire and the weldment burning heat of the arc and arc welding wire ends near the base metal and solder melted wire continuously fed, and proceeds along a certain trajectory, an arc weld pool solidified metal is removed to weld the molten solder is solidified into a shell covering the surface of the weld slag, slag of molten pool and weld metal for protection against arcing and the pool by the outside air intrusion.
For the submerged arc welding equipment, there are two. One is the constant wire submerged arc welding machine, wire feed speed according to the set speed constant, maintaining a relatively stable arc arc is to rely on self-regulation. Another is the shift wire submerged arc welding machine, which is the use of arc voltage as a feedback signal, after changing the wire feed speed control system, so as to maintain a relatively stable arc. Further, in order to ensure that the most suitable welding process in a stable position and reliable welding process, SAW also need more complex auxiliary equipment compatible with the welder, commonly used auxiliary equipment: weldments displacement equipment, welding machine operator (ie welding head displacement device), welding jig and weld equipment.
Since the SAW current, deep penetration, the groove form and size requirements are: a thickness of not less than 12mm plate beveling, in 12 ~ 20mm thickness can be used between the side welding, welding opposite gouging, more than when asked to open groove 20mm, but its blunt edge requires 5 ~ 6mm. Welding current based on the wire diameter, the thickness of the weldment, and the flux model is selected. Because of the large submerged arc welding current, welding the first layer prone to burn, often using the following welding process: SMAW welding back permanently submerged plate, lock bottom butt joint submerged arc welding, flux pad SAW.
HFW(High-frequency Welding)
In high-frequency current heating of the workpiece, and then applying pressure welding joints (see figure) is formed. A high-frequency current is concentrated along the surface of a conductor and flow along the path of least inductance over principle, the current will be concentrated heating of the workpiece surface to be welded, the thermoplastic state is reached or a partially molten state, extruding the molten metal on the workpiece and pressing the metal oxide, they form a welded joint. High-frequency welding common frequency range of 60 to 500 kHz. High frequency resistance welding high frequency welding points welding two kinds of high-frequency induction.
① High Frequency Resistance Welding: the contact with the wheel or as a sub-electrode high-frequency currents in the workpiece, suitable for continuous longitudinal seam welded pipe and spiral lap seam welding, boiler tube and fin heat exchanger spiral welded fin, can pipe external diameter of 1200 mm and a wall thickness of 16 mm, beam welding abdominal electrode thickness 9.5 mm, high productivity.
② High-frequency induction welding: a small diameter tube and the wall thickness of the workpiece by the induction heating coil can be welded to an outer diameter of 9 mm and 1 mm thin-walled tube. Commonly used in small diameter longitudinal pipe and brass seam welding, girth welding can also be used, but the power consumption is greater than the high-frequency resistance welding. The main parameters affecting the high-frequency welding quality is high-frequency power frequency, power, workpiece forming angle, welding speed and pressure from the squeeze, the electrode (or induction coil) and squeeze rollers. Major equipment has a high-frequency power supply, the workpiece forming apparatus and extrusion machinery. Stable high-frequency welding quality, high productivity and low cost. For high-efficiency automatic production line, the production of advanced methods slit tube.
For more, please visit website: http://www.hunanpipe.com/news357_654.html
Submerged arc welding is an arc welding under flux layer combustion method. Welding arc between the wire and the weldment burning heat of the arc and arc welding wire ends near the base metal and solder melted wire continuously fed, and proceeds along a certain trajectory, an arc weld pool solidified metal is removed to weld the molten solder is solidified into a shell covering the surface of the weld slag, slag of molten pool and weld metal for protection against arcing and the pool by the outside air intrusion.
For the submerged arc welding equipment, there are two. One is the constant wire submerged arc welding machine, wire feed speed according to the set speed constant, maintaining a relatively stable arc arc is to rely on self-regulation. Another is the shift wire submerged arc welding machine, which is the use of arc voltage as a feedback signal, after changing the wire feed speed control system, so as to maintain a relatively stable arc. Further, in order to ensure that the most suitable welding process in a stable position and reliable welding process, SAW also need more complex auxiliary equipment compatible with the welder, commonly used auxiliary equipment: weldments displacement equipment, welding machine operator (ie welding head displacement device), welding jig and weld equipment.
Since the SAW current, deep penetration, the groove form and size requirements are: a thickness of not less than 12mm plate beveling, in 12 ~ 20mm thickness can be used between the side welding, welding opposite gouging, more than when asked to open groove 20mm, but its blunt edge requires 5 ~ 6mm. Welding current based on the wire diameter, the thickness of the weldment, and the flux model is selected. Because of the large submerged arc welding current, welding the first layer prone to burn, often using the following welding process: SMAW welding back permanently submerged plate, lock bottom butt joint submerged arc welding, flux pad SAW.
HFW(High-frequency Welding)
In high-frequency current heating of the workpiece, and then applying pressure welding joints (see figure) is formed. A high-frequency current is concentrated along the surface of a conductor and flow along the path of least inductance over principle, the current will be concentrated heating of the workpiece surface to be welded, the thermoplastic state is reached or a partially molten state, extruding the molten metal on the workpiece and pressing the metal oxide, they form a welded joint. High-frequency welding common frequency range of 60 to 500 kHz. High frequency resistance welding high frequency welding points welding two kinds of high-frequency induction.
① High Frequency Resistance Welding: the contact with the wheel or as a sub-electrode high-frequency currents in the workpiece, suitable for continuous longitudinal seam welded pipe and spiral lap seam welding, boiler tube and fin heat exchanger spiral welded fin, can pipe external diameter of 1200 mm and a wall thickness of 16 mm, beam welding abdominal electrode thickness 9.5 mm, high productivity.
② High-frequency induction welding: a small diameter tube and the wall thickness of the workpiece by the induction heating coil can be welded to an outer diameter of 9 mm and 1 mm thin-walled tube. Commonly used in small diameter longitudinal pipe and brass seam welding, girth welding can also be used, but the power consumption is greater than the high-frequency resistance welding. The main parameters affecting the high-frequency welding quality is high-frequency power frequency, power, workpiece forming angle, welding speed and pressure from the squeeze, the electrode (or induction coil) and squeeze rollers. Major equipment has a high-frequency power supply, the workpiece forming apparatus and extrusion machinery. Stable high-frequency welding quality, high productivity and low cost. For high-efficiency automatic production line, the production of advanced methods slit tube.
For more, please visit website: http://www.hunanpipe.com/news357_654.html
Density of CS Pipe
Density is one of the numerous properties of steel. It is calculated by dividing the mass by the volume. Steel comes in many different forms. Density is calculated by dividing the mass by the volume. The density of carbon steel is approximately 7.85 g/cm3 (0.284 lb/in3).
There are many uses for steel. Stainless steel, for example, is used for surgical tools and kitchen utensils. It is a type of steel that contains low carbon levels and at least 10.5% of chromium. This results in corrosion resistance. Another kind of steel, tool steel, is used for metal cutting tools an drill bits because it is hard, but brittle. The amount of carbon in carbon steel determines the hardness of the steel. The more carbon it contains, the harder the steel. Carbon steel is often used for automobile parts.
Steel and its various forms have multiple uses around the world. The nature of the steel depends on its content, which results in varying densities. In most cases, the denser the steel, the harder it is.
The varying amounts of carbon, amongst other elements in each of the types of steel create a variety in densities or specific gravities. (Specific gravity or relative density is the ratio of a material's density to that of water.)
There are five major classifications of steels: carbon steel, alloy steel, high-strength low-alloy steel, stainless steel and tool steel. Carbon steels are the most common, containing various amounts of carbon, produce everything from machines to bedsprings to bobby pins. Alloy steels have definite amounts of vanadium, molybdenum, manganese, silicon and cooper. Alloy steels produce gears, carving knives and even roller skates. Stainless steels have chromium, nickel
amongst other alloy elements which sustains their color and reaction to rust. Stainless steel products include pipes, space capsules, surgical equipment to kitchen equipment. Last but not least, tool steels have tungsten, molybdenum
amongst other alloy elements. These elements create the strength and ability of the tool steel products, which include parts for manufacturing operations as well as machinery.
There are many uses for steel. Stainless steel, for example, is used for surgical tools and kitchen utensils. It is a type of steel that contains low carbon levels and at least 10.5% of chromium. This results in corrosion resistance. Another kind of steel, tool steel, is used for metal cutting tools an drill bits because it is hard, but brittle. The amount of carbon in carbon steel determines the hardness of the steel. The more carbon it contains, the harder the steel. Carbon steel is often used for automobile parts.
Steel and its various forms have multiple uses around the world. The nature of the steel depends on its content, which results in varying densities. In most cases, the denser the steel, the harder it is.
The varying amounts of carbon, amongst other elements in each of the types of steel create a variety in densities or specific gravities. (Specific gravity or relative density is the ratio of a material's density to that of water.)
There are five major classifications of steels: carbon steel, alloy steel, high-strength low-alloy steel, stainless steel and tool steel. Carbon steels are the most common, containing various amounts of carbon, produce everything from machines to bedsprings to bobby pins. Alloy steels have definite amounts of vanadium, molybdenum, manganese, silicon and cooper. Alloy steels produce gears, carving knives and even roller skates. Stainless steels have chromium, nickel
amongst other alloy elements which sustains their color and reaction to rust. Stainless steel products include pipes, space capsules, surgical equipment to kitchen equipment. Last but not least, tool steels have tungsten, molybdenum
amongst other alloy elements. These elements create the strength and ability of the tool steel products, which include parts for manufacturing operations as well as machinery.
2016年7月17日星期日
Black Steel Pipe
Black steel is a term given to steel pipe with a black oxide scale on the surface. This black oxide scale is formed when the pipe is forged and is typically sealed with a protective oil to prevent corrosion. Because of this oxide scale and protective film, black steel pipe requires little maintenance and is used for a wide variety of applications, including in water, steam, air and gas services. Black steel pipes are typically cut and threaded in the field.
Black steel pipe has high tensile strength, making it suitable for a variety of demanding applications. The toughness of black steel pipe guards against cracks and allows high loading capacities. A critical property of black steel pipe is its uniformity. Black steel's tensile strength is uniform along the entire length of pipe, which ensures consistent and predictable diameters.
Compared to bolted lattice structures, installation of black steel pipe can be quicker and easier. Threaded ends, flanges or welded construction allows designers the ability to make adjustments as required. In addition to strength, black steel pipe can be field-fabricated and easily worked to any length. The availability of multiple components and black steel fittings reduces costs and can speed up structural fabrication. Depending on the application and diameter, black steel pipe can be threaded or welded.
Once installed, black steel pipe has superior rust and corrosion resistance; without exterior damage such as nicks, scrapes or cuts, black steel is virtually maintenance-free. In addition, black steel piping does not shrink and retains its shape and strength. This eliminates any need to retighten or repair broken welds. This material is impervious to insects, rot or fire and, if required, can be further protected by painting or galvanizing, a powder coat or liquid application of zinc.
Black steel pipe has high tensile strength, making it suitable for a variety of demanding applications. The toughness of black steel pipe guards against cracks and allows high loading capacities. A critical property of black steel pipe is its uniformity. Black steel's tensile strength is uniform along the entire length of pipe, which ensures consistent and predictable diameters.
Compared to bolted lattice structures, installation of black steel pipe can be quicker and easier. Threaded ends, flanges or welded construction allows designers the ability to make adjustments as required. In addition to strength, black steel pipe can be field-fabricated and easily worked to any length. The availability of multiple components and black steel fittings reduces costs and can speed up structural fabrication. Depending on the application and diameter, black steel pipe can be threaded or welded.
Once installed, black steel pipe has superior rust and corrosion resistance; without exterior damage such as nicks, scrapes or cuts, black steel is virtually maintenance-free. In addition, black steel piping does not shrink and retains its shape and strength. This eliminates any need to retighten or repair broken welds. This material is impervious to insects, rot or fire and, if required, can be further protected by painting or galvanizing, a powder coat or liquid application of zinc.
DIN 30670
DIN 30670 refers to polyethylene coatings on steel pipes and fittings –Requirements and testing.
This standard specifies requirements for factory-applied three-layer extruded polyethylene-based coatings, and one- or multi-layered sintered polyethylene-based coatings for the corrosion protection of steel pipes and fittings. The coatings are suitable for the protection of buried or submerged steel pipes at design temperatures of –40 °C up to +80 °C. The present standard specifies requirements for coatings that are applied to longitudinally or spirally welded or seamless steel pipes and fittings used for the construction of pipelines for conveying liquids or gases. Applying this standard ensures that the PE coating provides sufficient protection against the mechanical, thermal and chemical loads occurring during operation, transport, storage and installation. DIN EN ISO 21809-1 specifies requirements at international level for three-layer extruded polyethylene- and polypropylene-based coatings for steel pipes for petroleum and natural gas pipeline transportation systems. The following fields of application are not covered by DIN EN ISO 21809-1: ─ all polyethylene-based coatings for steel pipes and fittings used for the conveyance and distribution of water and wastewater, ─ all polyethylene-based coatings for steel pipes and fittings in distribution pipelines for gaseous and liquid media, ─ single- and multi-layer sintered polyethylene-based coatings for steel pipes and fittings used for transport pipelines and distribution pipelines The present standard remains valid for the above fields of application. Two-layer polyethylene-based coatings are standardized at European level in DIN EN 10288 which was published in December 2003.
Materials shall be selected at the discretion of the coater because, depending on the installation and coating procedure, various materials can be used to comply with the minimum requirements specified in this standard for the finished coating. Any deviating requirements of the purchaser regarding the materials to be used shall be subject to agreement.The surface shall be prepared by removing rust by means of blast cleaning. Blast cleaning and any necessary subsequent work shall not result in the reduction of the minimum wall thickness specified in the technical delivery standards for the steel pipe. Residual abrasive dust shall be removed prior to coating.
This standard specifies requirements for factory-applied three-layer extruded polyethylene-based coatings, and one- or multi-layered sintered polyethylene-based coatings for the corrosion protection of steel pipes and fittings. The coatings are suitable for the protection of buried or submerged steel pipes at design temperatures of –40 °C up to +80 °C. The present standard specifies requirements for coatings that are applied to longitudinally or spirally welded or seamless steel pipes and fittings used for the construction of pipelines for conveying liquids or gases. Applying this standard ensures that the PE coating provides sufficient protection against the mechanical, thermal and chemical loads occurring during operation, transport, storage and installation. DIN EN ISO 21809-1 specifies requirements at international level for three-layer extruded polyethylene- and polypropylene-based coatings for steel pipes for petroleum and natural gas pipeline transportation systems. The following fields of application are not covered by DIN EN ISO 21809-1: ─ all polyethylene-based coatings for steel pipes and fittings used for the conveyance and distribution of water and wastewater, ─ all polyethylene-based coatings for steel pipes and fittings in distribution pipelines for gaseous and liquid media, ─ single- and multi-layer sintered polyethylene-based coatings for steel pipes and fittings used for transport pipelines and distribution pipelines The present standard remains valid for the above fields of application. Two-layer polyethylene-based coatings are standardized at European level in DIN EN 10288 which was published in December 2003.
Materials shall be selected at the discretion of the coater because, depending on the installation and coating procedure, various materials can be used to comply with the minimum requirements specified in this standard for the finished coating. Any deviating requirements of the purchaser regarding the materials to be used shall be subject to agreement.The surface shall be prepared by removing rust by means of blast cleaning. Blast cleaning and any necessary subsequent work shall not result in the reduction of the minimum wall thickness specified in the technical delivery standards for the steel pipe. Residual abrasive dust shall be removed prior to coating.
2016年7月15日星期五
Defects in the Process of Steel Pipe Production
Modern steel production has three major categories, namely, welded pipe, seamless pipe and seamless steel pipe.
Welded pipe is a metal strip into a tube by deformation processing, welding in the weld area forming, welding pipe welding process can be divided according to the furnace welding, high frequency resistance welding, TIG and plasma welding, etc; can be divided according to the form of the weld straight seam welding and spiral welding. Pipe injuries have common natural slag, cracks, holes, Weld and so on.
Seamless round tube is perforated or extruder processed into a capillary, and then rolling machine rolling forming small diameter pipes and thin-walled tube also repeated cold rolling - annealing process. Common injuries seamless nature are longitudinal, transverse cracking, warping and folding the inner and outer walls, pits, pitting and delamination.
The seamless pipe is heated primarily by reducing rolling, pickling, lubrication, drawing heat treatment and thermal annealing processes produce seamless steel pipe, steel pipe production of this same inevitably exist Weld Weld inclusions, such as welding and overheating problems. Whether welded steel pipe, seamless steel pipe or seamless steel pipes, cracks are the most common natural defects.
Welded pipe is a metal strip into a tube by deformation processing, welding in the weld area forming, welding pipe welding process can be divided according to the furnace welding, high frequency resistance welding, TIG and plasma welding, etc; can be divided according to the form of the weld straight seam welding and spiral welding. Pipe injuries have common natural slag, cracks, holes, Weld and so on.
Seamless round tube is perforated or extruder processed into a capillary, and then rolling machine rolling forming small diameter pipes and thin-walled tube also repeated cold rolling - annealing process. Common injuries seamless nature are longitudinal, transverse cracking, warping and folding the inner and outer walls, pits, pitting and delamination.
The seamless pipe is heated primarily by reducing rolling, pickling, lubrication, drawing heat treatment and thermal annealing processes produce seamless steel pipe, steel pipe production of this same inevitably exist Weld Weld inclusions, such as welding and overheating problems. Whether welded steel pipe, seamless steel pipe or seamless steel pipes, cracks are the most common natural defects.
Hydrostatic Pressure Testing of Pipes
Hydrostatic pressure test is conducted using a method for static characteristics of rock deformation measurement indicators.
Hydrostatic pressure test is a test. When the pressure vessel is made, after the newly installed container 3 prior to use or access, in order to test the strength of the container macro (if there is a crack, if the deformation is too large) and sealing the sealing point and weld, adding an appropriate amount of water in the container.
Determination of rock
Excavation in Rock a circular tunnel test, the test tunnel test section at one end portion is closed up concrete decking, using a high pressure water pump is forced into the test tunnel, so try cave rock surface subjected to a uniform water pressure caused rock deformation test changes again Underground radius or diameter, and then the relationship between pressure and deformation calculated deformation modulus and elastic resistance of rocks.
Determination of pressure parts
Usually closed pressurized parts, pressure parts of 1.25 or 1.5 times the design pressure of the injection pressure test water. When observed at least within 30min no leakage or no leakage through the joining surfaces of the cabinet or enclosure, the test is considered satisfactory. Large thick-walled castings may require a longer test time.
Hydrostatic pressure test is a test. When the pressure vessel is made, after the newly installed container 3 prior to use or access, in order to test the strength of the container macro (if there is a crack, if the deformation is too large) and sealing the sealing point and weld, adding an appropriate amount of water in the container.
Determination of rock
Excavation in Rock a circular tunnel test, the test tunnel test section at one end portion is closed up concrete decking, using a high pressure water pump is forced into the test tunnel, so try cave rock surface subjected to a uniform water pressure caused rock deformation test changes again Underground radius or diameter, and then the relationship between pressure and deformation calculated deformation modulus and elastic resistance of rocks.
Determination of pressure parts
Usually closed pressurized parts, pressure parts of 1.25 or 1.5 times the design pressure of the injection pressure test water. When observed at least within 30min no leakage or no leakage through the joining surfaces of the cabinet or enclosure, the test is considered satisfactory. Large thick-walled castings may require a longer test time.
2016年7月14日星期四
Pickling of Carbon Steel
Pickling of carbon steel is chemically pickled pipeline, container oxides, rust and oil on the surface is removed, to obtain a metallic luster surface, to ensure the cleanliness of the pipe wall, while after pickling rust treatment also makes the bottom wall of the metal to be protected, to prevent further corrosion, pipeline pickling is a key pipeline construction. Pipeline pickling method more pickling method currently used in the construction site and has trough pickling acid cycle, the cycle is divided pickling pickling line and off-line pickling. Circulation pickling is a pipe or hose coupling union constitute a loop with an acid pump acid into the circulating pipe pickling. It can be installed without removing the pipe, as long as the hydraulic components can be carried out even better off with a hose, which is called pickling line cycle. As some of the short tube or pipe fittings should not form a loop in the installation position detached, local loop circulating pickling connected with a hose or fitting, which is called pickling line outside the circle.
General requirements for circulating acid leaching as follows:
(1) The right formula, that formula pickling solution to be able to fully clear the wall oxide by chemical action, and because they can not make the wall excessive corrosion and rust again.
(2) Reasonable pickling loop, to ensure every part of the wall can be thoroughly and evenly pickling clean.
(3) Rational process and strict rules and special operations team with timely processing problems pickling process, to ensure the smooth progress of the work of pickling.
(4) Pickling and after the water should be thoroughly purged, and promptly flushed with hydraulic oil to ensure oil evenly throughout the inner tube, to produce the inner tube to flush out all the flying objects and when pickling.
For more, please visit:http://www.hunanpipe.com/news357_651.html
General requirements for circulating acid leaching as follows:
(1) The right formula, that formula pickling solution to be able to fully clear the wall oxide by chemical action, and because they can not make the wall excessive corrosion and rust again.
(2) Reasonable pickling loop, to ensure every part of the wall can be thoroughly and evenly pickling clean.
(3) Rational process and strict rules and special operations team with timely processing problems pickling process, to ensure the smooth progress of the work of pickling.
(4) Pickling and after the water should be thoroughly purged, and promptly flushed with hydraulic oil to ensure oil evenly throughout the inner tube, to produce the inner tube to flush out all the flying objects and when pickling.
For more, please visit:http://www.hunanpipe.com/news357_651.html
Difference between ERW and EFW
ERW is the first letter abbreviation for electric resistance welding.
ERW tube and submerged arc welding pipe significantly different, using a pressure-free filler metal welding, the weld is not filled with other ingredients, relying on high-frequency current skin effect and proximity effect, instantly heating the plate edge to welding temperature by squeezing rollers squeeze formed weld forging organizations. High-quality steel pipe welds require online or off-line heat treatment, welding zone structure refinement, quality ERW pipe welds and base metal can reach the same level of toughness, which is submerged arc welding process can not be achieved.
EFW namely electric fusion welding of the first letter abbreviation.
Submerged arc welding (SAW) - Electric welding (EFW) one, is through one or more consumable electrodes between the workpiece and the heating of the metal between the metal binding of a process, the arc and the metal filling material melted sufficiently, no pressure, filling the metal part of work-all from the electrodes.
Melting gas shielded arc welding (GMAW) - Electric welding (EFW) A, similar to this process and submerged arc welding, but it is protected from the inert gas, the effect will be better.
For more, please visit: http://www.hu-steel.com/news355_307.html
ERW tube and submerged arc welding pipe significantly different, using a pressure-free filler metal welding, the weld is not filled with other ingredients, relying on high-frequency current skin effect and proximity effect, instantly heating the plate edge to welding temperature by squeezing rollers squeeze formed weld forging organizations. High-quality steel pipe welds require online or off-line heat treatment, welding zone structure refinement, quality ERW pipe welds and base metal can reach the same level of toughness, which is submerged arc welding process can not be achieved.
EFW namely electric fusion welding of the first letter abbreviation.
Submerged arc welding (SAW) - Electric welding (EFW) one, is through one or more consumable electrodes between the workpiece and the heating of the metal between the metal binding of a process, the arc and the metal filling material melted sufficiently, no pressure, filling the metal part of work-all from the electrodes.
Melting gas shielded arc welding (GMAW) - Electric welding (EFW) A, similar to this process and submerged arc welding, but it is protected from the inert gas, the effect will be better.
For more, please visit: http://www.hu-steel.com/news355_307.html
2016年7月13日星期三
The Purpose of Cold Expansion
After cold expansion for lsaw steel pipe, steel tube and pipe end diameter will increase by about one percent difference in diameter of the diameter, roundness, and the pipe ends are greatly improved, also have greatly improved the straightness of the steel pipe, steel pipea length of about 0.5% reduction in wall thickness decreases by about 0.8%. Fully develop LSAW process should consider these changes, to determine the pipe plate width, length and thickness, and the pipe diameter in front of the enlarged diameter, in order to avoid the enlarged diameter steel pipe geometry reach the final requirements caused by substandard.
The purpose of cold expansion for lsaw steel pipe has the followings:
(1) Improve pipe end geometric dimensional accuracy of LSAW steel pipe, so that the diameter of the steel tube and pipe end, roundness, and the diameter of the pipe ends Poor meet the standard requirements, facilitate field welding
construction.
(2) Reduce inhomogeneous deformation of LSAW steel pipe forming and welding process and decrease the residual stress of forming and welding of tube, and improve its distribution, improve the overall mechanical properties of the steel
pipe.
(3) Inspect the steel pipe overall performance comprehensively and effectively.
(4) Improve the straight degree of lsaw steel pipe, especially for the smaller diameter LSAW pipe straight is more obvious.
for more the purpose of cold expansion,http://www.hunanpipe.com/news357_650.html
The purpose of cold expansion for lsaw steel pipe has the followings:
(1) Improve pipe end geometric dimensional accuracy of LSAW steel pipe, so that the diameter of the steel tube and pipe end, roundness, and the diameter of the pipe ends Poor meet the standard requirements, facilitate field welding
construction.
(2) Reduce inhomogeneous deformation of LSAW steel pipe forming and welding process and decrease the residual stress of forming and welding of tube, and improve its distribution, improve the overall mechanical properties of the steel
pipe.
(3) Inspect the steel pipe overall performance comprehensively and effectively.
(4) Improve the straight degree of lsaw steel pipe, especially for the smaller diameter LSAW pipe straight is more obvious.
for more the purpose of cold expansion,http://www.hunanpipe.com/news357_650.html
Difference between Black Steel Pipe and Galvanized Steel Pipe
Black steel pipe and galvanized steel pipe are the two most common kind of pipe applied to transport liquid and gas. They have several respects similar to each other and many people confuse one to the other one. What is the main difference between black steel pipe and galvanized steel pipe? Black steel pipe and galvanized pipe are made of steel, but galvanized pipe has a zinc coating while black pipe does not and therefore, galvanized pipe is more expensive and more durable. For transportation, black steel pipe tend to erode more easily than galvanized pipe and on account of this, it is more suitable for transporting gas and galvanized pipe is fit for carrying water instead of gas.
Galvanized pipe covered with a layer of zinc which makes it have higher ability of corrosion protection and help to prevent the accumulation of mineral deposits that will block the pipe. Galvanized pipe is mainly used for carrying water
to supply home and commercial buildings; it is also serve as scaffolding frames because of its rust prevention. Black steel pipe is manufactured as seamless which makes it a better type for gas transportation. It can be used for fire
sprinkler system since it can prevent fire better than galvanized pipe. Since it has a dark color surface that is form by iron oxide during the manufacturing process, it is called black steel pipe. The main difference between steel pipe
and galvanized pipe lies in the surface. Black steel pipe is uncoated and made without steam, and therefore, it is widely used for transporting gas like propane and natural gas to residential and commercial building.
Galvanized pipe has zinc on the surface so the mineral will flack off as time goes by and block the pipe. This will lead to a burst. In view of this, transport gas by galvanized pipes is dangerous so it is often used in carrying water.
Black steel pipe, on the other hand, is not suitable for water transport. Black steel pipes are tending to corrode in water and mineral of the pipe will dissolve into the water and clog the line as well.
General speaking, black steel pipe is cheaper than galvanized pipe. This is due to the zinc coating on galvanized pipe and the manufacturing process making it. Black steel pipe is low maintenance; it costs less to the fitting. Black steel pipe and galvanized steel pipe looked similar in the eye of many people. So how to differentiate this two pipe? Here are three main methods. First, you can examine the color of the pipe. Black steel pipe is darker than galvanized
pipe; it is flat black while galvanized pipe is silver and gray. Second, galvanized pipe is usually applied for water carriage and black steel pipe for gas deliver, you can tell the difference by the material they carry. And last, you can tell from the year the pipe being used. Black steel pipe used later than galvanized pipe. If the pipe is installed after 1950s, it’s likely to be black steel.
for more difference between black steel pipe and galvanized steel pipe, http://www.hu-steel.com/news355_306.html
Galvanized pipe covered with a layer of zinc which makes it have higher ability of corrosion protection and help to prevent the accumulation of mineral deposits that will block the pipe. Galvanized pipe is mainly used for carrying water
to supply home and commercial buildings; it is also serve as scaffolding frames because of its rust prevention. Black steel pipe is manufactured as seamless which makes it a better type for gas transportation. It can be used for fire
sprinkler system since it can prevent fire better than galvanized pipe. Since it has a dark color surface that is form by iron oxide during the manufacturing process, it is called black steel pipe. The main difference between steel pipe
and galvanized pipe lies in the surface. Black steel pipe is uncoated and made without steam, and therefore, it is widely used for transporting gas like propane and natural gas to residential and commercial building.
Galvanized pipe has zinc on the surface so the mineral will flack off as time goes by and block the pipe. This will lead to a burst. In view of this, transport gas by galvanized pipes is dangerous so it is often used in carrying water.
Black steel pipe, on the other hand, is not suitable for water transport. Black steel pipes are tending to corrode in water and mineral of the pipe will dissolve into the water and clog the line as well.
General speaking, black steel pipe is cheaper than galvanized pipe. This is due to the zinc coating on galvanized pipe and the manufacturing process making it. Black steel pipe is low maintenance; it costs less to the fitting. Black steel pipe and galvanized steel pipe looked similar in the eye of many people. So how to differentiate this two pipe? Here are three main methods. First, you can examine the color of the pipe. Black steel pipe is darker than galvanized
pipe; it is flat black while galvanized pipe is silver and gray. Second, galvanized pipe is usually applied for water carriage and black steel pipe for gas deliver, you can tell the difference by the material they carry. And last, you can tell from the year the pipe being used. Black steel pipe used later than galvanized pipe. If the pipe is installed after 1950s, it’s likely to be black steel.
for more difference between black steel pipe and galvanized steel pipe, http://www.hu-steel.com/news355_306.html
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