The basic principles of the outer coating selected city gas pipeline
a, good insulation properties and mechanical properties;
b, good resistance to cathodic disbanding performance;
c, good resistance to water, gas permeability;
d, good chemical resistance properties of soaking and aging;
e, low temperature and high temperature performance;
f, easy mending and mending;
g, the price is reasonable.
2016年8月31日星期三
ERW Steel Pipe Corrosion Problems
(1) Source of evaluation of external coating
Literature states: "steel surface condition is called environment that can coating and soil pipe insulation four weeks, four weeks the tube surface soil conditions are different and therefore the corrosion protection layer of the pipe is an important barrier to prevent soil erosion. " This is the basic starting point of the evaluation outer coating performance. Joe Leighton British company discussed from two different perspectives pipe coating system: European perspective is to make it able to withstand moisture, prevent corrosion, it is the "barrier" point of view. From this point of view it had a "PE" protective layer method. The North American point of view is to make it possible to oxidation resistance, chemical resistance and resistance to negative release properties to prevent corrosion, which is the "glue" point of view. From this point of view, resulting in a "FBE" law protective layer.
Another current trend is to the two foreign viewpoints known as "barrier" and "bond" combined, the development of a new point of view, the forthcoming European "PE" barrier protection layer method and North America "FBE" protection layer method to combine the development of an integrated-type "3PE" law protective layer. The new ideas, new technology, new methods in our country has begun to promote the application.
(2) the basic functions of the outer coating of steel
There are two aspects:
First, make the ERW steel pipe surface from electrochemical corrosion, bacterial corrosion protection of soil basic physical media,
Second, resist the soil medium move creep stress, basic mechanical protection method static stress and abrasion strength and structure and so on.
Literature states: "steel surface condition is called environment that can coating and soil pipe insulation four weeks, four weeks the tube surface soil conditions are different and therefore the corrosion protection layer of the pipe is an important barrier to prevent soil erosion. " This is the basic starting point of the evaluation outer coating performance. Joe Leighton British company discussed from two different perspectives pipe coating system: European perspective is to make it able to withstand moisture, prevent corrosion, it is the "barrier" point of view. From this point of view it had a "PE" protective layer method. The North American point of view is to make it possible to oxidation resistance, chemical resistance and resistance to negative release properties to prevent corrosion, which is the "glue" point of view. From this point of view, resulting in a "FBE" law protective layer.
Another current trend is to the two foreign viewpoints known as "barrier" and "bond" combined, the development of a new point of view, the forthcoming European "PE" barrier protection layer method and North America "FBE" protection layer method to combine the development of an integrated-type "3PE" law protective layer. The new ideas, new technology, new methods in our country has begun to promote the application.
(2) the basic functions of the outer coating of steel
There are two aspects:
First, make the ERW steel pipe surface from electrochemical corrosion, bacterial corrosion protection of soil basic physical media,
Second, resist the soil medium move creep stress, basic mechanical protection method static stress and abrasion strength and structure and so on.
2016年8月30日星期二
Quality Problems of Straight Pipe Joints in Inspection
Blank perforated temperature varies according to the raw material strange strange. Thermal expansion pipe but mostly in 1200 ℃, when the carbon content and other alloying elements more temperature slightly lower.
The second key is to try to reduce the heating operation scale quantities. Especially in hot kneading elbow, straight seam steel pipe from leaving things life expectancy and kneading pipe surface quality, pleading even more severe.
In the straight seam steel pipe production process, because the primary process is in a hot state, so the heating operation is resolution product quality is very important process.
The heat with the furnace, according to their results, and reheating furnace is divided into two kinds; the former is used to billet heated from room temperature to the processing temperature; the latter is used in the process in the blank reheated to the required processing temperature. Heating will be wrong in the outer surface of the tube surface may exhibit cracks, folds and migraine pain and other waste reason.
There are many kinds of heating furnace, but the primary use is a ring furnace. This furnace has an annular hearth, it can slowly change the direction of the diameter of the blank along the bottom of the load from the entrance, a reversal can be used at the outlet of the heating and soaking temperature to the rule kind of stove. This operation is the key blank is heated uniformly heated to a temperature suitable for processing. Because a great impact on the quality of the perforation, that is, when the temperature of the process piercing is an important condition affecting the quality, it is generally the temperature of the billet piercing working is to manipulate.
The second key is to try to reduce the heating operation scale quantities. Especially in hot kneading elbow, straight seam steel pipe from leaving things life expectancy and kneading pipe surface quality, pleading even more severe.
In the straight seam steel pipe production process, because the primary process is in a hot state, so the heating operation is resolution product quality is very important process.
The heat with the furnace, according to their results, and reheating furnace is divided into two kinds; the former is used to billet heated from room temperature to the processing temperature; the latter is used in the process in the blank reheated to the required processing temperature. Heating will be wrong in the outer surface of the tube surface may exhibit cracks, folds and migraine pain and other waste reason.
There are many kinds of heating furnace, but the primary use is a ring furnace. This furnace has an annular hearth, it can slowly change the direction of the diameter of the blank along the bottom of the load from the entrance, a reversal can be used at the outlet of the heating and soaking temperature to the rule kind of stove. This operation is the key blank is heated uniformly heated to a temperature suitable for processing. Because a great impact on the quality of the perforation, that is, when the temperature of the process piercing is an important condition affecting the quality, it is generally the temperature of the billet piercing working is to manipulate.
Production Features of High-frequency Electric Resistance Welded Steel Pipe
High-frequency resistance welded steel pipe(erw steel pipe) has the following characteristics:
(1) High-frequency resistance welding filler metal is a no pressure welding.
(2) High-frequency resistance welding high welding speed, high production efficiency. Since the current high concentration of energy in the weld zone, fast heating, and thus high welding speed. For example, China has introduced 426 units, the maximum welding speed 45m / min, the minimum welding speed 15m / min.
(3) The weld heat affected zone. Due to the highly concentrated energy welding, heating speed, high welding speed, the workpiece strong self-cooling effect, so the heat affected zone.
(4) High welding production technology and management level requirements. High-frequency welding is resistance welding in a continuous production line, the welding speed, high production efficiency, factors affecting the welding process and more, you must have a high level of technology and management level, in order to weld the whole production line more harmonization of elements up to a steady access to quality welded steel pipe.
(1) High-frequency resistance welding filler metal is a no pressure welding.
(2) High-frequency resistance welding high welding speed, high production efficiency. Since the current high concentration of energy in the weld zone, fast heating, and thus high welding speed. For example, China has introduced 426 units, the maximum welding speed 45m / min, the minimum welding speed 15m / min.
(3) The weld heat affected zone. Due to the highly concentrated energy welding, heating speed, high welding speed, the workpiece strong self-cooling effect, so the heat affected zone.
(4) High welding production technology and management level requirements. High-frequency welding is resistance welding in a continuous production line, the welding speed, high production efficiency, factors affecting the welding process and more, you must have a high level of technology and management level, in order to weld the whole production line more harmonization of elements up to a steady access to quality welded steel pipe.
Disadvantages of high frequency welded pipe forming roller row
Disadvantages of high frequency electric resistance welding pipe(erw steel pipe) forming roller row is following below:
1. Weakening crude molding deformation is the root of the pipe defects. Since the one-sided pursuit of the common roll to reduce the number of roll and roll changing times, thus reducing the horizontal row roll forming roll stand (breakdown stand), so that the original level by the amount of deformation of the deformation roll stand, more transferred to the discharge roller section and precision molding machine. Row roller segment consists of many efflux roll and some of the inner roller composed mainly efflux roll by applying pressure to the outer surface of the steel strip to deform the inner surface of the roll so that deformation of the inner strip.
2. The crude molding deformation is not sufficient, increase the precision molding machine, a number of mill. In the high-frequency welded pipe production, the effects of the deformed state edge of the strip on the welding quality greatly. The best steel tube curvature of the opening edge portion of the pipe and finished very close, and this deformation required to complete the rough shaping stage. The row roll forming technology since the horizontal roll stand
reduction in crude forming stage is difficult to do, had to be deformed into the discharge roller segment and fine machine, but in the row roll segment, due to the structure of the device is also very difficult to guarantee, the result
is the roundness of welded pipe difference after.
3. Pipe intrinsic product quality. Since the outer and inner roll cage roll steel strip uneven deformation, so that the degree of partial pipe material hardening increases, the residual stress is large and unevenly distributed. Although the dimensions of products can meet the requirements, but the relative performance of the material steel base material has changed greatly, pipe internal toughness, extensibility, resistance to stress corrosion and so has been compromised, which is used in cold regions casing great influence of high grade steel pipeline corrosion and requires media.
4. The lack of thrust, unstable welding speed. In ERW molding process, totally dependent on the drive roller thrust provided by the steel strip to overcome the deformation resistance and stable welding speed. Since the horizontal rack reduced, so that the deformation of the thrust to overcome, particularly in areas large strip thickness, high strength material, the phenomenon is prone to insufficient thrust of the strip forming velocity fluctuations. In order to compensate for the lack of thrust, stable welding speed is also required to increase the number of precision molding machine.
5. Equipment poor rigidity, and high strength thick-walled pipe production difficult. Early compared with the current row roll forming machine is used in many interior rollers, but after the increase in the number of rollers also have
some problems.
1. Weakening crude molding deformation is the root of the pipe defects. Since the one-sided pursuit of the common roll to reduce the number of roll and roll changing times, thus reducing the horizontal row roll forming roll stand (breakdown stand), so that the original level by the amount of deformation of the deformation roll stand, more transferred to the discharge roller section and precision molding machine. Row roller segment consists of many efflux roll and some of the inner roller composed mainly efflux roll by applying pressure to the outer surface of the steel strip to deform the inner surface of the roll so that deformation of the inner strip.
2. The crude molding deformation is not sufficient, increase the precision molding machine, a number of mill. In the high-frequency welded pipe production, the effects of the deformed state edge of the strip on the welding quality greatly. The best steel tube curvature of the opening edge portion of the pipe and finished very close, and this deformation required to complete the rough shaping stage. The row roll forming technology since the horizontal roll stand
reduction in crude forming stage is difficult to do, had to be deformed into the discharge roller segment and fine machine, but in the row roll segment, due to the structure of the device is also very difficult to guarantee, the result
is the roundness of welded pipe difference after.
3. Pipe intrinsic product quality. Since the outer and inner roll cage roll steel strip uneven deformation, so that the degree of partial pipe material hardening increases, the residual stress is large and unevenly distributed. Although the dimensions of products can meet the requirements, but the relative performance of the material steel base material has changed greatly, pipe internal toughness, extensibility, resistance to stress corrosion and so has been compromised, which is used in cold regions casing great influence of high grade steel pipeline corrosion and requires media.
4. The lack of thrust, unstable welding speed. In ERW molding process, totally dependent on the drive roller thrust provided by the steel strip to overcome the deformation resistance and stable welding speed. Since the horizontal rack reduced, so that the deformation of the thrust to overcome, particularly in areas large strip thickness, high strength material, the phenomenon is prone to insufficient thrust of the strip forming velocity fluctuations. In order to compensate for the lack of thrust, stable welding speed is also required to increase the number of precision molding machine.
5. Equipment poor rigidity, and high strength thick-walled pipe production difficult. Early compared with the current row roll forming machine is used in many interior rollers, but after the increase in the number of rollers also have
some problems.
Technical advantages of high frequency welded pipe forming roller
Technical advantages of high frequency electric resistance welding pipe(erw steel pipe) forming roller is following below:
(1) Reducing the number of rough roll forming, reducing the cost of the roll and roll change time. Row roll forming technology of crude molding machine generally consists of two horizontal roller racks with many inner and outer row roller for all pipe dimensions within the range of products, the first rack roll Normally only a single set, but roll and roll within the second frame you need to have several sets. This roll forming machine is reduced compared to the number of rolls, the investment had been reduced accordingly.
(2) Improving the quality of the pipe. By a number of small-diameter discharge roll instead of roll forming machine large-diameter horizontal rolls, roll surface speed difference is reduced, improving the steel edge stretching action to improve the quality of the pipe side portions.
(3) Reducing the roll change time and improve productivity. Rough shaping rolls and rolls Despite several sets of inner row, but not to replace the pipe with a diameter of each roll change is necessary. Precision machine and sizing machine is widely used and so rigid frame and quick-change device, roll change greatly shorten the time from the previous 1 to 2 classes a few tens of minutes. Roll change time is shortened, increased production, and therefore row roll forming technology has not only gained popularity in diameter pipe production, but also in the small-diameter pipe production has also been promoted. It can be said after the mid-1980s, is a row of roll forming technology development period.
(1) Reducing the number of rough roll forming, reducing the cost of the roll and roll change time. Row roll forming technology of crude molding machine generally consists of two horizontal roller racks with many inner and outer row roller for all pipe dimensions within the range of products, the first rack roll Normally only a single set, but roll and roll within the second frame you need to have several sets. This roll forming machine is reduced compared to the number of rolls, the investment had been reduced accordingly.
(2) Improving the quality of the pipe. By a number of small-diameter discharge roll instead of roll forming machine large-diameter horizontal rolls, roll surface speed difference is reduced, improving the steel edge stretching action to improve the quality of the pipe side portions.
(3) Reducing the roll change time and improve productivity. Rough shaping rolls and rolls Despite several sets of inner row, but not to replace the pipe with a diameter of each roll change is necessary. Precision machine and sizing machine is widely used and so rigid frame and quick-change device, roll change greatly shorten the time from the previous 1 to 2 classes a few tens of minutes. Roll change time is shortened, increased production, and therefore row roll forming technology has not only gained popularity in diameter pipe production, but also in the small-diameter pipe production has also been promoted. It can be said after the mid-1980s, is a row of roll forming technology development period.
2016年8月29日星期一
Stress on High-frequency Straight Seam Resistance Welding Pipe Grooving Corrosion
High-frequency electric resistance welded (ERW) pipe as a whole without heat treatment, to achieve circumferential weld residual stress around 350MPa, close to the yield strength of the pipe. When the weld processing into working electrode, the residual stress is reduced to 100MPa or less. Circumferential tensile stress can reduce the corrosion potential of welds, accelerated corrosion, increased sensitivity coefficient trench etching after the heat treatment of the welded pipe, the circumferential weld tensile residual stress is small, to 10 ~ 100MPa, after processing into a working electrode its circumferential tensile stress is little change.
Trench etching is generally believed that acute heat in the welding process, the results of local tissue metal and chemical change caused by quenching. In the high frequency resistance welding process, within the initial 0.1s, temperature was raised to 1600 ℃, the integration process section MnS decomposed into S or converted to FeS, within the next 4 ~ 6s, the temperature dropped to 400 ℃, then water-cooled to room temperature. S and sulfide-rich seam zone is through the rapid heating, rapid cooling to achieve. For high sulfur content (mass fraction> 0.01%) steel, the corrosion of the trench produce MnS inclusions about; the loss of low sulfur content steel trench produces solder alloy, residual stress and increase the carbon content related.
Uneven temperature field of welding process is a root cause of welding stress and deformation. In the small thickness of the weldments, welding residual stress is substantially plane stress, stress in the thickness direction is small. In the free state the welding plate, in the vicinity of the weld and the tensile stress is generally in the stress away from the weld compared. Residual Stress can affect the strength of the weldment, stiffness, stability, accuracy and corrosion resistance. The elimination of residual stress, the general overall heat treatment. Since the annealing temperature is too high will result in material strength and organizational changes or the second phase precipitates, the annealing temperature is too low to remove the effects of residual stress is unlikely, therefore, to the steel to stress annealing 500 ℃ 1h, after slow cooling, reducing the welding residual stress member, improve the uniformity of the organization and composition. Correspondence between before and after heat treatment corrosion current density and tensile stress, it can be seen, not heat-treated samples corrosion current density increases with the tensile stress significantly increased, and the corrosion current density is much larger than the sample after the heat treatment. It showed that after heat treatment, corrosion resistance ERW welded plate significantly improved.
Trench etching is generally believed that acute heat in the welding process, the results of local tissue metal and chemical change caused by quenching. In the high frequency resistance welding process, within the initial 0.1s, temperature was raised to 1600 ℃, the integration process section MnS decomposed into S or converted to FeS, within the next 4 ~ 6s, the temperature dropped to 400 ℃, then water-cooled to room temperature. S and sulfide-rich seam zone is through the rapid heating, rapid cooling to achieve. For high sulfur content (mass fraction> 0.01%) steel, the corrosion of the trench produce MnS inclusions about; the loss of low sulfur content steel trench produces solder alloy, residual stress and increase the carbon content related.
Uneven temperature field of welding process is a root cause of welding stress and deformation. In the small thickness of the weldments, welding residual stress is substantially plane stress, stress in the thickness direction is small. In the free state the welding plate, in the vicinity of the weld and the tensile stress is generally in the stress away from the weld compared. Residual Stress can affect the strength of the weldment, stiffness, stability, accuracy and corrosion resistance. The elimination of residual stress, the general overall heat treatment. Since the annealing temperature is too high will result in material strength and organizational changes or the second phase precipitates, the annealing temperature is too low to remove the effects of residual stress is unlikely, therefore, to the steel to stress annealing 500 ℃ 1h, after slow cooling, reducing the welding residual stress member, improve the uniformity of the organization and composition. Correspondence between before and after heat treatment corrosion current density and tensile stress, it can be seen, not heat-treated samples corrosion current density increases with the tensile stress significantly increased, and the corrosion current density is much larger than the sample after the heat treatment. It showed that after heat treatment, corrosion resistance ERW welded plate significantly improved.
Common Defects of ERW Steel Pipe Welding
ERW steel pipe is fed into the molding machine, deformed into a cylindrical tube through an induction loop or contact welding angle, the magnetic field around the induction coil current is induced by the edge of the strip, the strip edge due to its resistance generated thermal resistance is heated, the heated extruded strip edge forming roll extrusion welds. High-frequency welding metal is not added, it is actually a forge welding. If production control is better, does not remain fused surface of molten metal or oxide. HAZ shaped like a drum, because the edges of the strip into the strip entering the high-frequency current to generate heat from the end and side portions of the strip edges. HAZ color slightly darker than the base metal because welding carbon steel strip edge heating to diffusion, cooling weld carbon is absorbed in the strip edges.
Common defects of erw steel pipe welding
High frequency pipe may be a variety of welding defects. Each defect has many different names, there is no recognized professional terminology. Name given below defective, another common name in brackets defects: ① inclusions (burnt black oxide); ② pre-arc (white burnt oxide); ③ lack of fusion (slotted); ④ edge lack of fusion (wavy edge); ⑤ central insufficient fusion (cold welding central); ⑥ stick welding (cold welding); ⑦ cast welding (welding brittle); ⑧ pores (pinholes); ⑨ skip welding. These defects are not all but the most common high-frequency welding defects.
Common defects of erw steel pipe welding
High frequency pipe may be a variety of welding defects. Each defect has many different names, there is no recognized professional terminology. Name given below defective, another common name in brackets defects: ① inclusions (burnt black oxide); ② pre-arc (white burnt oxide); ③ lack of fusion (slotted); ④ edge lack of fusion (wavy edge); ⑤ central insufficient fusion (cold welding central); ⑥ stick welding (cold welding); ⑦ cast welding (welding brittle); ⑧ pores (pinholes); ⑨ skip welding. These defects are not all but the most common high-frequency welding defects.
2016年8月25日星期四
Ultrasonic Testing of Seamless Steel Tubes
The ultrasonic probe to be completed by the power of sound energy between each other and transform the physical characteristics of ultrasonic waves in an elastic medium to convey when the pipe ultrasonic flaw detection principle
foundation. Experiencing disadvantage emitted ultrasonic beam directed to convey in a tube, reflecting both the occurrence of waves and wave attenuation occurs. After signal processing flaw detector, such as the selection reflection detection, echo signal can be obtained shortcomings, such as the use penetration testing method can be achieved by virtue of shortcomings signal attenuation through the waves. Both can give quantitative shortcomings indicated by the
instrument.
Using the principle of electromagnetic induction or piezoelectric effect can stimulate the inner tube is not the same type of ultrasound. Thus, the piezoelectric ultrasonic and electromagnetic ultrasonic pipe can be used for ultrasonic inspection. But EMAT only for ferromagnetic materials.
Selection of shear (or plate wave) reflection method (or penetration method) in the probe and the pipe relative movement active state inspection, as long as the special large-diameter pipe inspection technology can be conducted. Should take the initiative to check the time or skill to ensure that the beam tube full scan appearance.
Such inspection shortcomings longitudinal beam conveyed in the tube wall along the circumferential direction; disadvantage when checking lateral beam conveyed in the wall along the tube axis. Longitudinal and transverse defects inspection should be carried out in two opposite directions of the tube.
When the demand side did not make identification lateral side only drawback for inspection longitudinal shortcomings. Endorsed by both sides to negotiate, longitudinal and transverse defects inspection can be carried out only in one direction of the tube.
Choose a good coupling active or craft examining them, and not detract from the appearance of the pipe coupling medium.
foundation. Experiencing disadvantage emitted ultrasonic beam directed to convey in a tube, reflecting both the occurrence of waves and wave attenuation occurs. After signal processing flaw detector, such as the selection reflection detection, echo signal can be obtained shortcomings, such as the use penetration testing method can be achieved by virtue of shortcomings signal attenuation through the waves. Both can give quantitative shortcomings indicated by the
instrument.
Using the principle of electromagnetic induction or piezoelectric effect can stimulate the inner tube is not the same type of ultrasound. Thus, the piezoelectric ultrasonic and electromagnetic ultrasonic pipe can be used for ultrasonic inspection. But EMAT only for ferromagnetic materials.
Selection of shear (or plate wave) reflection method (or penetration method) in the probe and the pipe relative movement active state inspection, as long as the special large-diameter pipe inspection technology can be conducted. Should take the initiative to check the time or skill to ensure that the beam tube full scan appearance.
Such inspection shortcomings longitudinal beam conveyed in the tube wall along the circumferential direction; disadvantage when checking lateral beam conveyed in the wall along the tube axis. Longitudinal and transverse defects inspection should be carried out in two opposite directions of the tube.
When the demand side did not make identification lateral side only drawback for inspection longitudinal shortcomings. Endorsed by both sides to negotiate, longitudinal and transverse defects inspection can be carried out only in one direction of the tube.
Choose a good coupling active or craft examining them, and not detract from the appearance of the pipe coupling medium.
Production Failure Analysis of ERW Steel Pipe Unit
In the production of ERW steel pipe process will encounter many problems, the following will mainly talk about some of the issues given diameter machine analysis. In contrast, the lowest rate fixed problems mill, and the process it is also relatively simple, common sizing mill's production somethin There are several types.
1, Sizing scratch scratches primary attack in the horizontal and vertical axis on both sides of the pipe cross-section, multi-formed from flat roll and vertical roll pass of marginal. Especially after pass marginal R rounded sharpened, the following questions are presented once may cause injuries.
2, Drill pipe drill pipe doubt is rare, the chance of comparison usually thin-walled tube produced episodes, and this is because of poor primary rigid thin-walled tube, and because the wall is thinner simple roll bite. So assume the following questions will form a drill pipe in the production of the incidents.
3, The tubes not round tube-round shape is usually oval, round and ribbed gourd-shaped three.
4, Straighten the fundamental principle is to use leverage, the tube axial deformation attack again, and then to straighten intentions.
1, Sizing scratch scratches primary attack in the horizontal and vertical axis on both sides of the pipe cross-section, multi-formed from flat roll and vertical roll pass of marginal. Especially after pass marginal R rounded sharpened, the following questions are presented once may cause injuries.
2, Drill pipe drill pipe doubt is rare, the chance of comparison usually thin-walled tube produced episodes, and this is because of poor primary rigid thin-walled tube, and because the wall is thinner simple roll bite. So assume the following questions will form a drill pipe in the production of the incidents.
3, The tubes not round tube-round shape is usually oval, round and ribbed gourd-shaped three.
4, Straighten the fundamental principle is to use leverage, the tube axial deformation attack again, and then to straighten intentions.
2016年8月23日星期二
Straightening Machine
Leveler 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.
Principle of straightening machine
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.
Principle of straightening machine
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.
NDT Testing
NDT testing means without prejudice or affect the detected object performance, not hurt at being provided to detect objects within the organization, the use of material internal structural abnormalities or defects heat, sound, light, electricity, magnetism and other reactions caused by changes to physical or chemical methods as a means of using modern technology and equipment, equipment, the specimen surface and the interior of the structure, properties, and defect type state, nature, number, shape, position, size, distribution and change inspection and test methods [1]. Non-destructive testing is an effective tool of industrial development is essential, to a certain extent reflects the level of industrial development of a country, the importance of non-destructive testing has been recognized, the main ray inspection (RT), ultrasonic testing (UT), magnetic particle testing (MT) and liquid penetrant testing (PT) four. There are other NDT methods eddy current testing (ECT), acoustic emission testing (AE), thermal imaging / infrared (TIR), leak testing (LT), the AC field measurement techniques (ACFMT), magnetic flux leakage testing (MFL), far-field test detection (RFT), ultrasonic time of flight diffraction method (TOFD) and the like.
NDT testing is the use of sound material, optical, magnetic and electrical characteristics such as, without prejudice or affect the performance of the detection object premise of the existence of defects or unevenness in the detection of the test object, given defect size, location the nature and quantity of information. Compared with the destructive testing, nondestructive testing has the following characteristics. The first is a non-destructive, because when it is done without compromising detection performance by using a detection object; a second comprehensive, since the detection is non-destructive, so the object can be detected 100% comprehensive testing, if necessary this is destructive detection impossible; the third has a full, destructive detection generally apply only to the raw materials testing, such as mechanical engineering commonly used in tension, compression, bending, etc., are for nondestructive testing manufacturing of raw materials, finished products and for the supplies, unless the service is not ready to let it continue, otherwise it is not destructive detection and non-destructive testing without damaging the object to be detected by the use of performance. Therefore, it is not only the raw materials used to manufacture each intermediate step of the process, until the final finished products for the entire testing, but also on the service in the device for testing.
NDT Visual inspection: 1, the weld surface defect inspection. Check the weld surface cracks, incomplete penetration and weld leak welding quality. 2, the state examination. Check the surface cracks, peeling, cable, scratches, dents, bumps, spots, corrosion and other defects. 3, cavity inspection. When certain products (such as worm gear pumps, engines, etc.) work, according to the technical requirements of the project will be remote visual inspection. 4, assembly inspection. When required, and when needed, using the same three-dimensional industrial video endoscope assembly quality inspection; or a step after assembly is complete, check the parts and components assembled position meets the conditions for drawing or technical requirements; the existence of assembly defects. 5, extra material inspection. Check the product within the lumen of the residual dust, foreign objects and other remnants.
For more, please visit:http://www.hu-steel.com/news355_333.html
NDT testing is the use of sound material, optical, magnetic and electrical characteristics such as, without prejudice or affect the performance of the detection object premise of the existence of defects or unevenness in the detection of the test object, given defect size, location the nature and quantity of information. Compared with the destructive testing, nondestructive testing has the following characteristics. The first is a non-destructive, because when it is done without compromising detection performance by using a detection object; a second comprehensive, since the detection is non-destructive, so the object can be detected 100% comprehensive testing, if necessary this is destructive detection impossible; the third has a full, destructive detection generally apply only to the raw materials testing, such as mechanical engineering commonly used in tension, compression, bending, etc., are for nondestructive testing manufacturing of raw materials, finished products and for the supplies, unless the service is not ready to let it continue, otherwise it is not destructive detection and non-destructive testing without damaging the object to be detected by the use of performance. Therefore, it is not only the raw materials used to manufacture each intermediate step of the process, until the final finished products for the entire testing, but also on the service in the device for testing.
NDT Visual inspection: 1, the weld surface defect inspection. Check the weld surface cracks, incomplete penetration and weld leak welding quality. 2, the state examination. Check the surface cracks, peeling, cable, scratches, dents, bumps, spots, corrosion and other defects. 3, cavity inspection. When certain products (such as worm gear pumps, engines, etc.) work, according to the technical requirements of the project will be remote visual inspection. 4, assembly inspection. When required, and when needed, using the same three-dimensional industrial video endoscope assembly quality inspection; or a step after assembly is complete, check the parts and components assembled position meets the conditions for drawing or technical requirements; the existence of assembly defects. 5, extra material inspection. Check the product within the lumen of the residual dust, foreign objects and other remnants.
For more, please visit:http://www.hu-steel.com/news355_333.html
2016年8月22日星期一
Mechanical Expanding and Expanding Characteristics
Comparison of mechanical expanding and hydraulic expanding has the following advantages:
(1) The production of large diameter steel pipe aging rate. Since the water pressure expanding low-pressure water need to be filled, then pressurized to achieve further boosted when steel yield. As production gradually increasing
diameter, efficiency is greatly reduced, for example, to pipe length 12m dollars, when 609.6mm (24in) diameter steel pipe hydrostatic expansion, 36 per hour, while the mechanical expanding, each 28 hours. Of 1067mm (42in) pipe, expanding the use of water pressure, 18 per hour, while 23 per hour when the mechanical expanding. That mechanical expanding, and its efficiency is not the size of the diameter relationship, so relatively speaking increased diameter and also high efficiency.
(2) Easily meet the stringent requirements for steel pipe inner diameter. When long-distance pipeline laying, welding steel pipe installed in the field site, with an inner diameter of the base, the smaller the inner diameter of the wrong side two steel tube end after docking, the smaller transport resistance, so the pipe inner diameter accuracy requirements increasingly stringent, while expanding pressure is precisely controlled by the outer mold jacket pipe diameter, the inner diameter dimensional accuracy can not be guaranteed. Mechanical expanding head is inserted into the enlarged diameter steel pipe was expanding, therefore, you can control the precision steel pipe inner diameter, regardless of wall thickness variation.
(3) Ovality good. Expanding water pressure, because outside of the welds in contact with the outer mold jacket to near the recessed wall, destroyed the pipe ovality. Mechanical expanding, as long as the weld head aligned expanding segments of the trench, when expanding unfettered welds to form a smooth surface, thus effectively reducing the damage caused by the welded parts.
(4) Pipe end shape and high dimensional accuracy. Weld effect expanding the comparison ends pressed into conical steel required pressure head against the head of the press insert seal ring radial seal up, so that the steel pipe and tube end indenter contact portion with expanded diameter steel pipe effect tubular body portion inconsistent. The mechanical expanding not have this phenomenon, pipe ends good shape and dimensions of the field site installation and butt are favorable.
(1) The production of large diameter steel pipe aging rate. Since the water pressure expanding low-pressure water need to be filled, then pressurized to achieve further boosted when steel yield. As production gradually increasing
diameter, efficiency is greatly reduced, for example, to pipe length 12m dollars, when 609.6mm (24in) diameter steel pipe hydrostatic expansion, 36 per hour, while the mechanical expanding, each 28 hours. Of 1067mm (42in) pipe, expanding the use of water pressure, 18 per hour, while 23 per hour when the mechanical expanding. That mechanical expanding, and its efficiency is not the size of the diameter relationship, so relatively speaking increased diameter and also high efficiency.
(2) Easily meet the stringent requirements for steel pipe inner diameter. When long-distance pipeline laying, welding steel pipe installed in the field site, with an inner diameter of the base, the smaller the inner diameter of the wrong side two steel tube end after docking, the smaller transport resistance, so the pipe inner diameter accuracy requirements increasingly stringent, while expanding pressure is precisely controlled by the outer mold jacket pipe diameter, the inner diameter dimensional accuracy can not be guaranteed. Mechanical expanding head is inserted into the enlarged diameter steel pipe was expanding, therefore, you can control the precision steel pipe inner diameter, regardless of wall thickness variation.
(3) Ovality good. Expanding water pressure, because outside of the welds in contact with the outer mold jacket to near the recessed wall, destroyed the pipe ovality. Mechanical expanding, as long as the weld head aligned expanding segments of the trench, when expanding unfettered welds to form a smooth surface, thus effectively reducing the damage caused by the welded parts.
(4) Pipe end shape and high dimensional accuracy. Weld effect expanding the comparison ends pressed into conical steel required pressure head against the head of the press insert seal ring radial seal up, so that the steel pipe and tube end indenter contact portion with expanded diameter steel pipe effect tubular body portion inconsistent. The mechanical expanding not have this phenomenon, pipe ends good shape and dimensions of the field site installation and butt are favorable.
Cold Expanded of Large Diameter Straight Welded Pipe
Cold expanded of large diameter straight welded pipe is a use of hydraulic or mechanical means urging the steel pipe from the steel wall along the radially outward dilatation pressure molding process. Mechanical than hydraulic mode, the
device is simple and more efficient use of steel in high-precision machining conditions more precise, in the reservoir emptying large diameter pipe joints straight no need to use, now the world's most advanced several large-caliber
straight seam steel pipe expanding pipeline processes are adopted, the process is as follows:
Mechanical expanding is the use of the split-side diameter-enlarged portion of the expansion segments radially, so that the longitudinal direction of the tube in a stepwise manner, the full length of the tube segments to achieve plastic deformation process. It is divided into five stages
1, The initial stage of a full circle. Segments open until all the segments are exposed to the pipe wall, this time in the step length range within steel tube radius of each point are almost identical, steel preliminary full circle.
2, Nominal inside diameter of the stage. Anterior segments from the start position to reduce the speed of movement, until reaching the required position, this position is within the finished pipe quality requirements circumferential
position.
3, Springback compensation stage. Segments 2 at the position of the start phase further low speed, until reaching the required position, this position is within the requirements of the design process of elastic recovery before the pipe circumferential position.
4, Pressure stable stage. Segments before playing the complex inner pipe circumferential position remain intact for some time, this is the stable phase packing equipment and expanding process requirements.
5, Unloading regression phase. Circumferential segments starting position quickly retracted from the inner pipe bomb before the complex until the arrival of the initial position of the enlarged diameter, which is expanding process requirements shrink the diameter of the smallest segments.
device is simple and more efficient use of steel in high-precision machining conditions more precise, in the reservoir emptying large diameter pipe joints straight no need to use, now the world's most advanced several large-caliber
straight seam steel pipe expanding pipeline processes are adopted, the process is as follows:
Mechanical expanding is the use of the split-side diameter-enlarged portion of the expansion segments radially, so that the longitudinal direction of the tube in a stepwise manner, the full length of the tube segments to achieve plastic deformation process. It is divided into five stages
1, The initial stage of a full circle. Segments open until all the segments are exposed to the pipe wall, this time in the step length range within steel tube radius of each point are almost identical, steel preliminary full circle.
2, Nominal inside diameter of the stage. Anterior segments from the start position to reduce the speed of movement, until reaching the required position, this position is within the finished pipe quality requirements circumferential
position.
3, Springback compensation stage. Segments 2 at the position of the start phase further low speed, until reaching the required position, this position is within the requirements of the design process of elastic recovery before the pipe circumferential position.
4, Pressure stable stage. Segments before playing the complex inner pipe circumferential position remain intact for some time, this is the stable phase packing equipment and expanding process requirements.
5, Unloading regression phase. Circumferential segments starting position quickly retracted from the inner pipe bomb before the complex until the arrival of the initial position of the enlarged diameter, which is expanding process requirements shrink the diameter of the smallest segments.
2016年8月15日星期一
Storage of Steel Tube
Pipe may not be directly stacked on the floor, steel or concrete surface, the first layer of steel pipe from the ground at a distance not less than 0.20m. To avoid pipe damp, dust and pollution, steel pipe (or tube bundle) shall be placed in a dusty, damp places, tying both ends of the pipe must be protected with plastic or paper bags, etc., to prevent dust from entering.
Rack or stack level should be neatly arranged, and there is a clear marker number. Pipe should heat number (Lot), variety of different sizes and materials are placed in the designated rack or stack position. The same rack or stack position is not allowed to store the same size as (or similar), the same type of material and outline different heats of steel.
To prevent bending or steel pipe table injury, steel pipe (or tube bundles) should be placed at appropriate intervals and in the same horizontal plane on the sleepers, end of the tube to ensure alignment. For annealed brass, aluminum and similar hose should be placed between layers of isolation sleepers, each for at least two sleepers should be placed in a vertical pipe, and up and down on the positive, to ensure straight alignment. If the pipe
In case of the absence of feeder layer code (including code square stamp) stacked, should be properly placed wedge or use other methods to prevent rolling of steel pipe.
After cold-rolled, cold-drawn or bright annealed steel pipe does not allow open storage. If that stock conditions, open storage should be required to take appropriate precautions to avoid rain, snow, fog and other corrosive media and a lot of dust pollution pipe.
For more, please visit webiste:http://www.hu-steel.com/news355_329.html
Rack or stack level should be neatly arranged, and there is a clear marker number. Pipe should heat number (Lot), variety of different sizes and materials are placed in the designated rack or stack position. The same rack or stack position is not allowed to store the same size as (or similar), the same type of material and outline different heats of steel.
To prevent bending or steel pipe table injury, steel pipe (or tube bundles) should be placed at appropriate intervals and in the same horizontal plane on the sleepers, end of the tube to ensure alignment. For annealed brass, aluminum and similar hose should be placed between layers of isolation sleepers, each for at least two sleepers should be placed in a vertical pipe, and up and down on the positive, to ensure straight alignment. If the pipe
In case of the absence of feeder layer code (including code square stamp) stacked, should be properly placed wedge or use other methods to prevent rolling of steel pipe.
After cold-rolled, cold-drawn or bright annealed steel pipe does not allow open storage. If that stock conditions, open storage should be required to take appropriate precautions to avoid rain, snow, fog and other corrosive media and a lot of dust pollution pipe.
For more, please visit webiste:http://www.hu-steel.com/news355_329.html
Package of Steel Tube
Package of steel tube requirements substantially divided into two categories: one is the common type of bale, and the other is with totes similar container load.
Bundled package
Avoid pipe damage by baling and transportation process, baling signs to a uniform and consistent.
The same bundle of steel pipe should be the same furnace number (Lot), with the steel grade, the same specifications of the steel pipe, should not be mixed furnace (batch) bundling, it should be less than a bundle into small bundles.
Weight of each pipe bundle should not exceed 50kg. The user's consent to increase the bale weight, but the most important can not exceed 80kg.
Pipe bundle respect to the blunt end, should be aligned at one end, the tube ends are aligned side by less than 20mm, each bundle of steel pipe length difference less than 10mm, but according to the length of the pipe is usually the order of each bundle pipe length difference is less than 5mm, the longest pipe bundle and Minister of not more than 10mm.
Containers package
Cold-rolled or cold-drawn seamless steel tubes, the surface finish of hot-rolled stainless steel tube, the container may be used (such as plastic containers and wooden box) packaging.
Weight of the container shall be packed in accordance with Table 1. Negotiated by both sides, the maximum weight of each container can be increased.
When the pipe into the container, the inner wall of the container should be fitted cardboard, plastic sheeting or other moisture-proof material. Containers should not be closely seepage.
For steel containers and packaging, a label should be included in the container. The outer end surface of the container should also be linked to a label.
Steel with special packaging requirements, by agreement between.
Bundled package
Avoid pipe damage by baling and transportation process, baling signs to a uniform and consistent.
The same bundle of steel pipe should be the same furnace number (Lot), with the steel grade, the same specifications of the steel pipe, should not be mixed furnace (batch) bundling, it should be less than a bundle into small bundles.
Weight of each pipe bundle should not exceed 50kg. The user's consent to increase the bale weight, but the most important can not exceed 80kg.
Pipe bundle respect to the blunt end, should be aligned at one end, the tube ends are aligned side by less than 20mm, each bundle of steel pipe length difference less than 10mm, but according to the length of the pipe is usually the order of each bundle pipe length difference is less than 5mm, the longest pipe bundle and Minister of not more than 10mm.
Containers package
Cold-rolled or cold-drawn seamless steel tubes, the surface finish of hot-rolled stainless steel tube, the container may be used (such as plastic containers and wooden box) packaging.
Weight of the container shall be packed in accordance with Table 1. Negotiated by both sides, the maximum weight of each container can be increased.
When the pipe into the container, the inner wall of the container should be fitted cardboard, plastic sheeting or other moisture-proof material. Containers should not be closely seepage.
For steel containers and packaging, a label should be included in the container. The outer end surface of the container should also be linked to a label.
Steel with special packaging requirements, by agreement between.
2016年8月14日星期日
Concrete Filled Steel Pipe
Concrete is concrete poured into the steel pipe and tamped to increase the strength and rigidity of the steel pipe. In general, we have concrete strength steel in concrete C50 or less as ordinary steel concrete; concrete strength steel in the concrete above C50 called steel high strength concrete; concrete strength CFT C100 above called steel high strength concrete.
As we all know, high compressive strength of concrete. But bending is weak, and steel, especially steel strong bending resistance, good plasticity, but when pressed easily instability and loss of axial compression capabilities. Concrete and steel in the structure will be able to combine the advantages of both, can make concrete is laterally compressed state, the compressive strength can be doubled. At the same time due to the presence of concrete, improve the rigidity of the steel pipe, which together play a role, thus greatly improving the carrying capacity. As a new steel concrete composite structures, mainly in the axial compressive force and a smaller compression eccentric member-based, is widely used in the frame structure (such as factories and high-rise).
Part of the concrete column is less and less welds, simple structure, the pedestal reserved cup often used in concrete foundation plug-foot column, which manufacturing plant is relatively simple, while the smaller component weight, lifting and transportation are more easy, very simple construction, steel and concrete columns were rolled sheet, plate thickness is not large, generally less than 40mm, and regardless of the factory site butt welding, have no difficulty. At the same time, compared with reinforced concrete columns, steel sheath having a reinforced concrete column function, the role of both the longitudinal and transverse reinforcement stirrups, so no steel tube, steel cutting and saving a series of steel banding process, and Since the column jacket pipe itself is resistant to lateral pressure template, but also save the formwork and form removal processes. In recent years, quite common pumping concrete, poured on-site no difficulty, and the creation of widely used high Paola not vibrated concrete method of construction, more streamlined site - concrete steps, simple construction. In the lower portion of the column is also open temporary watering hole with a bottom-pouring of concrete pump concrete way, not only fast, but also to ensure the quality of watering. Moreover, after pouring, steel pipe is fairly stable humidity conditions, water can not evaporate, eliminating the need for water conservation processes, simplifying the process of curing concrete.
As we all know, high compressive strength of concrete. But bending is weak, and steel, especially steel strong bending resistance, good plasticity, but when pressed easily instability and loss of axial compression capabilities. Concrete and steel in the structure will be able to combine the advantages of both, can make concrete is laterally compressed state, the compressive strength can be doubled. At the same time due to the presence of concrete, improve the rigidity of the steel pipe, which together play a role, thus greatly improving the carrying capacity. As a new steel concrete composite structures, mainly in the axial compressive force and a smaller compression eccentric member-based, is widely used in the frame structure (such as factories and high-rise).
Part of the concrete column is less and less welds, simple structure, the pedestal reserved cup often used in concrete foundation plug-foot column, which manufacturing plant is relatively simple, while the smaller component weight, lifting and transportation are more easy, very simple construction, steel and concrete columns were rolled sheet, plate thickness is not large, generally less than 40mm, and regardless of the factory site butt welding, have no difficulty. At the same time, compared with reinforced concrete columns, steel sheath having a reinforced concrete column function, the role of both the longitudinal and transverse reinforcement stirrups, so no steel tube, steel cutting and saving a series of steel banding process, and Since the column jacket pipe itself is resistant to lateral pressure template, but also save the formwork and form removal processes. In recent years, quite common pumping concrete, poured on-site no difficulty, and the creation of widely used high Paola not vibrated concrete method of construction, more streamlined site - concrete steps, simple construction. In the lower portion of the column is also open temporary watering hole with a bottom-pouring of concrete pump concrete way, not only fast, but also to ensure the quality of watering. Moreover, after pouring, steel pipe is fairly stable humidity conditions, water can not evaporate, eliminating the need for water conservation processes, simplifying the process of curing concrete.
Mortar Lined Steel Pipe
Pipe bending strength mortar coating experiments pipe diameter is large pipe bending easy and flat easy. Hours flat diameter is less susceptible to bending easy. It is believed that the mortar coating lining the curving of the pipe due to the coating flaking is easy to occur. Cement mortar lining with ordinary cement with a certain thickness of the sand, additives, according to the mixture ratio design, made of mortar mix, through a dedicated construction machinery and equipment, applied to the pipe wall, forming a certain thickness of the mortar coating, solidification after becoming lining. Cement mortar lining, relying on its own strength combined with the pipe wall of the support, its structure uniform, dense, hard and solid, if then brushing the surface of epoxy mortar, water after roughness coefficient which can also be reduced. Cement mortar lining is not only simple physical barrier barrier properties, but by the chemical properties of the cement mortar lining to protect the pipeline.
Cement mortar lining has several obvious advantages:
1. Avoid pipe wall corrosion rust generation, so long pipeline to maintain good water status, low coefficient of friction.
2. Because the lining of the coating isolated, water is not in contact with the metal pipe to ensure water quality.
3. Made of cement mortar pipe wall corrosion, prevents corrosion perforation, extending the life of the pipeline,
4. Cement mortar coating materials easily obtained, short construction period, good corrosion protection, reduce the cost of the pipeline project.
Cement mortar lining has several obvious advantages:
1. Avoid pipe wall corrosion rust generation, so long pipeline to maintain good water status, low coefficient of friction.
2. Because the lining of the coating isolated, water is not in contact with the metal pipe to ensure water quality.
3. Made of cement mortar pipe wall corrosion, prevents corrosion perforation, extending the life of the pipeline,
4. Cement mortar coating materials easily obtained, short construction period, good corrosion protection, reduce the cost of the pipeline project.
2016年8月4日星期四
HDG and GI diffrence
HDG: Also called hot dip galvanized and hot-dip galvanized: is an effective way of metal corrosion, mainly for various sectors of the metal structure facilities. Is immersed steel rust after about 500 ℃ melted liquid zinc, steel member attached to the surface layer of zinc, which serve the purpose of preservation.
Cold galvanized: is galvanized, zinc less, only 10-50g / m2, so is the use of electrolysis or other parts of the metal surface of the material attached to a metal film craft. The formation of uniform, dense, good adhesion of the metal layer process can serve to prevent corrosion, improve the wear resistance, electrical conductivity, reflectivity and enhance the aesthetics and so on.
HDG and GI diffrence:
1, Different corrosion resistance, hot-dip galvanizing cold galvanizing several times.
2, On the way different jobs: HDG is 450-480 degrees in the molten liquid zinc plated zinc plating is cold at room temperature by plating zinc plating or other methods.
3, Zinc coating thickness, is far greater than the thickness of the hot-dip galvanizing cold galvanizing.
4, The surface smoothness is different than the hot-dip galvanizing cold galvanizing look nice and smooth.
5, Different prices, the price is higher than the hot-dip galvanized cold galvanizing.
6, Cold galvanizing can only plated one side, the whole quest galvanized plating.
7, Different adhesion, cold galvanizing adhesion better than galvanized.
8, Different charges, according to the thickness of the hot-dip galvanized material charges, according to the majority of cold-plated square meter charges.
Cold galvanized: is galvanized, zinc less, only 10-50g / m2, so is the use of electrolysis or other parts of the metal surface of the material attached to a metal film craft. The formation of uniform, dense, good adhesion of the metal layer process can serve to prevent corrosion, improve the wear resistance, electrical conductivity, reflectivity and enhance the aesthetics and so on.
HDG and GI diffrence:
1, Different corrosion resistance, hot-dip galvanizing cold galvanizing several times.
2, On the way different jobs: HDG is 450-480 degrees in the molten liquid zinc plated zinc plating is cold at room temperature by plating zinc plating or other methods.
3, Zinc coating thickness, is far greater than the thickness of the hot-dip galvanizing cold galvanizing.
4, The surface smoothness is different than the hot-dip galvanizing cold galvanizing look nice and smooth.
5, Different prices, the price is higher than the hot-dip galvanized cold galvanizing.
6, Cold galvanizing can only plated one side, the whole quest galvanized plating.
7, Different adhesion, cold galvanizing adhesion better than galvanized.
8, Different charges, according to the thickness of the hot-dip galvanized material charges, according to the majority of cold-plated square meter charges.
What is Seam Pipe
Seam pipe refers to the strip or plate bending round, square and other shapes and then welded into the surface jointed pipe. Seam pipe is using a blank plate or strip.
With the advancement of high-quality steel rolling production as well as the rapid development of welding and inspection techniques, and continuously improve the quality of welds, pipe joints increasing varieties and specifications, and in more and more areas instead of seamless steel tubes. Seam pipe is lower than seamless steel pipe on cost, high production efficiency.
According to different welding methods can be divided arc welded pipe, high-frequency or low frequency electric resistance welded pipe, gas pipe, stove pipe, Bundy tubes.
Press seam shape classification can be divided into longitudinal and spiral welded pipe.
By end-use is divided into general welded pipe, galvanized pipe, oxygen blowing pipe, wire casing, metric pipe, roller tube, deep well pump tube, automotive tube, transformer tube, welding thin-walled tube, welding shaped tube and spiral welded pipe.
Press the end of the shape classification is divided into circular pipe and shaped (square, flat, etc.) pipe.
With the advancement of high-quality steel rolling production as well as the rapid development of welding and inspection techniques, and continuously improve the quality of welds, pipe joints increasing varieties and specifications, and in more and more areas instead of seamless steel tubes. Seam pipe is lower than seamless steel pipe on cost, high production efficiency.
According to different welding methods can be divided arc welded pipe, high-frequency or low frequency electric resistance welded pipe, gas pipe, stove pipe, Bundy tubes.
Press seam shape classification can be divided into longitudinal and spiral welded pipe.
By end-use is divided into general welded pipe, galvanized pipe, oxygen blowing pipe, wire casing, metric pipe, roller tube, deep well pump tube, automotive tube, transformer tube, welding thin-walled tube, welding shaped tube and spiral welded pipe.
Press the end of the shape classification is divided into circular pipe and shaped (square, flat, etc.) pipe.
Improve the Accuracy of Spiral Steel Pipe Wall Thickness
Spiral pipe quality has always been subject to focus attention of the masses, for the detection process, the most important is the spiral pipe application performance Bale.
Spiral pipe bending point refers to the phenomenon of metal material having a yield, the degree of bending of the sample is very important in the spiral pipe forming the initial time, because it can test out the spiral steel pipe subjected to external pressure when the reaction, if the pressure test of the spiral steel pipe the critical point, according to customer requirements can be appropriately reinforcing spiral pipe to greater affordability.
When the solenoid drop occurs, it should distinguish between the lower yield point. The yield point and the yield stress is the maximum force before the first drop of the sample occurred; lower yield point refers to when excluding the initial transient effects, the yield phases of minimum stress. Hardness index mainly metal materials ability to resist a hard object surface indentation, known as hardness.
Depending on the test methods and scope, it can be divided into Brinell hardness spiral, Rockwell hardness, Vickers hardness, Shore hardness, micro hardness and high temperature hardness. Commonly used for pipe Brinell, Rockwell, Vickers hardness of three.
Spiral pipe bending point refers to the phenomenon of metal material having a yield, the degree of bending of the sample is very important in the spiral pipe forming the initial time, because it can test out the spiral steel pipe subjected to external pressure when the reaction, if the pressure test of the spiral steel pipe the critical point, according to customer requirements can be appropriately reinforcing spiral pipe to greater affordability.
When the solenoid drop occurs, it should distinguish between the lower yield point. The yield point and the yield stress is the maximum force before the first drop of the sample occurred; lower yield point refers to when excluding the initial transient effects, the yield phases of minimum stress. Hardness index mainly metal materials ability to resist a hard object surface indentation, known as hardness.
Depending on the test methods and scope, it can be divided into Brinell hardness spiral, Rockwell hardness, Vickers hardness, Shore hardness, micro hardness and high temperature hardness. Commonly used for pipe Brinell, Rockwell, Vickers hardness of three.
Passivation
After the metal by the oxidizing medium treatment, the corrosion rate than the original untreated before a significant drop phenomenon is called passivation metal. Its main mechanism of passivation film can be used to explain the theory, namely that the passivation is due to the effect of metal and oxidizing medium, when the role of the metal surface to generate a very thin, dense, good coverage performance can be rigidly attached to the metal passivation film on the surface. This film exists as a separate phase, oxygen and metal compound is usually yes. It plays metal and corrosive media, the role of completely separated, preventing direct contact with the metal and corrosive media, so that the metal basically stopped dissolved to form a passive state to achieve the effect of preventing corrosion. Passivation is the last chemical cleaning process step is the key step, the aim of the anti-corrosion material. Such as boiler pickling, water washing, rinsing, the metal surface is very clean, very activation, are vulnerable to corrosion, it must be passivated immediately after cleaning the metal surface to form a protective film, corrosion mitigation.
The last chemical cleaning process step is a key step, the aim of the anti-corrosion material. Such as boiler pickling, water washing, rinsing, the metal surface is very clean, very activation, are vulnerable to corrosion, it must be passivated immediately after cleaning the metal surface to form a protective film, corrosion mitigation.
Full stainless steel pickling passivation treatment to remove all types of grease, rust, scale, welding spots and other dirt, the surface becomes uniform silver after processing, greatly improving the corrosion resistance of stainless steel, suitable for various types of stainless steel parts, sheet metal and their equipment.
Simple, easy to use, economical and practical, while adding a highly efficient inhibitor, fog inhibitor, appeared to prevent the metal corrosion and hydrogen embrittlement, suppressing the generation of mist. Especially for small complex parts, the situation is not suitable anointed, better than the market similar products.
The last chemical cleaning process step is a key step, the aim of the anti-corrosion material. Such as boiler pickling, water washing, rinsing, the metal surface is very clean, very activation, are vulnerable to corrosion, it must be passivated immediately after cleaning the metal surface to form a protective film, corrosion mitigation.
Full stainless steel pickling passivation treatment to remove all types of grease, rust, scale, welding spots and other dirt, the surface becomes uniform silver after processing, greatly improving the corrosion resistance of stainless steel, suitable for various types of stainless steel parts, sheet metal and their equipment.
Simple, easy to use, economical and practical, while adding a highly efficient inhibitor, fog inhibitor, appeared to prevent the metal corrosion and hydrogen embrittlement, suppressing the generation of mist. Especially for small complex parts, the situation is not suitable anointed, better than the market similar products.
2016年8月1日星期一
The Basic Principle of Eddy Current Testing
Eddy current testing is one of many NDT method, it is applied - the basic theory of electromagnetism as a basis conductor detection. Vortex generated from the phenomenon called electromagnetic induction. When alternating current is applied to the conductor, for example copper wire, a magnetic field is generated in the magnetic field surrounding the conductor and the conductor space. Eddy current is induced, which flows in a loop. It is called - vortex ‖, because it is surrounded with a liquid or a gas barrier in the loop flowing form is the same. If a conductor is placed in the varying magnetic field, eddy currents generated in the conductor, and the eddy currents also produce their own magnetic field with alternating current rises and expansion, with the alternating current decreases and blanking. So when some of the properties of the conductor surface or near-surface defects or measuring metal material changes will affect the intensity and distribution of the vortex, so we can change the situation together to detect the vortex, and thus may be internally indirect knowledge questions performance deficiencies exist and whether the metal has changed.
Eddy current NDT as a tool of big advantage is that it can do a variety of inspection and measurement. In the right environment, eddy current can be used:
1, Crack, defect inspection
2, The material thickness measurement
3, Coating thickness measurement
4, The conductive material is measured
Advantages of eddy current testing include:
1, Sensitivity to small cracks and other defects
2, Detection of surface and near surface defects speed, high sensitivity
3, The test results are immediacy
4, Good device interface
5, Only need to make a few preparations
6, The test probe does not require contact with the measured object
7, You can check the shape and size of complex conductor
Eddy current NDT as a tool of big advantage is that it can do a variety of inspection and measurement. In the right environment, eddy current can be used:
1, Crack, defect inspection
2, The material thickness measurement
3, Coating thickness measurement
4, The conductive material is measured
Advantages of eddy current testing include:
1, Sensitivity to small cracks and other defects
2, Detection of surface and near surface defects speed, high sensitivity
3, The test results are immediacy
4, Good device interface
5, Only need to make a few preparations
6, The test probe does not require contact with the measured object
7, You can check the shape and size of complex conductor
Features of Eddy Current Testing
1, The metal tube, rod, wire rod detection, contact is not required and no need for a coupling medium. So high detection speed, easy to implement automated testing, especially for online P seized.
2, High sensitivity for the detection of surface defects, and in a certain range with good linearity indication of the size of the different defects can be evaluated, it can be used as a quality management and control.
3, Eddy currents are many factors, such as cracks, material, size, shape and electrical conductivity and permeability and the like. Spleen using specific circuits for processing, can filter out certain factors inhibit other factors, thereby making it possible for an individual above factors for effective testing.
4, Since the inspection and do not have contact with the workpiece without coupling medium, it can be detected at high temperatures. As the probe can be inserted into the distant job, so the workpiece can be narrow and deep wall area (including walls) and other testing.
5, The use of electrical display, it is possible to store and reproduce the data comparison and processing.
6, Eddy current testing of the object must be a conductive material, and due to electromagnetic induction, and applies only to the metal surface defect detection, NA detect internal defects of metallic materials deep.
7, The penetration depth of the metal surface induced eddy currents varies with frequency, high excitation frequency eddy current density at the surface of the metal, with the decrease of the excitation frequency eddy current penetration depth is increased, but the surface eddy current density is reduced, the depth and surface flaw detection hurt sensitivity is conflicting, difficult to strike. When a material eddy current flaw detection, the need for comprehensive consideration according to the material, surface condition, testing standards, and then determine the NDT programs and technical parameters.
8. When using encircling coil eddy current testing, coil cover is a tube, rod or wire on the circumference of a length, to obtain information on the factors that influence the entire circle cumulative result, the specific location of the defect in which the circumference It can not be determined.
9, rotating probe type eddy current testing method can accurately stuck defect location, sensitivity and resolution are high, but the detection area is small, in the test material when the need for comprehensive scanning, inspection slower.
10, Or in equivalent eddy current testing has been comparing the detected phase defects make accurate qualitative and quantitative judgment yet to be developed.
2, High sensitivity for the detection of surface defects, and in a certain range with good linearity indication of the size of the different defects can be evaluated, it can be used as a quality management and control.
3, Eddy currents are many factors, such as cracks, material, size, shape and electrical conductivity and permeability and the like. Spleen using specific circuits for processing, can filter out certain factors inhibit other factors, thereby making it possible for an individual above factors for effective testing.
4, Since the inspection and do not have contact with the workpiece without coupling medium, it can be detected at high temperatures. As the probe can be inserted into the distant job, so the workpiece can be narrow and deep wall area (including walls) and other testing.
5, The use of electrical display, it is possible to store and reproduce the data comparison and processing.
6, Eddy current testing of the object must be a conductive material, and due to electromagnetic induction, and applies only to the metal surface defect detection, NA detect internal defects of metallic materials deep.
7, The penetration depth of the metal surface induced eddy currents varies with frequency, high excitation frequency eddy current density at the surface of the metal, with the decrease of the excitation frequency eddy current penetration depth is increased, but the surface eddy current density is reduced, the depth and surface flaw detection hurt sensitivity is conflicting, difficult to strike. When a material eddy current flaw detection, the need for comprehensive consideration according to the material, surface condition, testing standards, and then determine the NDT programs and technical parameters.
8. When using encircling coil eddy current testing, coil cover is a tube, rod or wire on the circumference of a length, to obtain information on the factors that influence the entire circle cumulative result, the specific location of the defect in which the circumference It can not be determined.
9, rotating probe type eddy current testing method can accurately stuck defect location, sensitivity and resolution are high, but the detection area is small, in the test material when the need for comprehensive scanning, inspection slower.
10, Or in equivalent eddy current testing has been comparing the detected phase defects make accurate qualitative and quantitative judgment yet to be developed.
The Ways to Solve Annealing of Incompetence
(1) Increase in the length of the annealing furnace, the furnace from the original length to 23.832m 34.852m, since the annealing time to solve the problem caused by the increase in production problems.
(2) Using the roof flat flame burner and burner Forward burner combination, solved due to the use of the forward end portion of the burner and a side burner caused by lateral transverse sectional temperature unevenness solved drawn tube annealing temperature is low part of the problem.
(3) The use of heat-resistant steel in high temperature section hearth roll, water cooled roll against the water-cooled rolls causes the contact portion of the low-temperature region, the annealing temperature is reduced in a longitudinal section of a temperature gradient.
(4) Changing the original lower portion and an upper portion of the annealing furnace baffle wall of the structure and improve the life of the baffle wall. Since the original block firewall short life, often resulting in baffle wall to collapse, resulting in clogging of burner end lower portion, so that the lower portion of annealing furnace heating capacity decrease, resulting in a large temperature difference between the furnace profile. Annealing after the transformation to solve this problem, to ensure the full annealing of cold drawn tubes.
Through equipment modification, technical and economic indicators have reached the annealing process requirements, annealing quality improved significantly, so that the mechanical properties of cold drawn seamless qualified rate of 97.913% before transformation increased to 99.015% after the transformation.
(2) Using the roof flat flame burner and burner Forward burner combination, solved due to the use of the forward end portion of the burner and a side burner caused by lateral transverse sectional temperature unevenness solved drawn tube annealing temperature is low part of the problem.
(3) The use of heat-resistant steel in high temperature section hearth roll, water cooled roll against the water-cooled rolls causes the contact portion of the low-temperature region, the annealing temperature is reduced in a longitudinal section of a temperature gradient.
(4) Changing the original lower portion and an upper portion of the annealing furnace baffle wall of the structure and improve the life of the baffle wall. Since the original block firewall short life, often resulting in baffle wall to collapse, resulting in clogging of burner end lower portion, so that the lower portion of annealing furnace heating capacity decrease, resulting in a large temperature difference between the furnace profile. Annealing after the transformation to solve this problem, to ensure the full annealing of cold drawn tubes.
Through equipment modification, technical and economic indicators have reached the annealing process requirements, annealing quality improved significantly, so that the mechanical properties of cold drawn seamless qualified rate of 97.913% before transformation increased to 99.015% after the transformation.
Disqualification of Seamless Pipe Mechanical Properties
Seamless pipe mechanical properties failed mainly in its low elongation and yield point is not obvious, the mechanical properties of the above-mentioned non-conforming product samples for metallurgical testing, found cold drawn pipe spherical pearlite organization and very fine grains ferrite.
Globular pearlite structure is a typical annealing inadequate organization. Normal cold drawing process requirements, the microstructure after annealing should be ferrite and pearlite flaky globular pearlite formation temperature is 750 ~ 830 °C, so the globular pearlite, suggesting that the low annealing temperature, annealing insufficient.
Extremely fine grains of ferrite is also an annealing inadequate organization, and its globular pearlite formation conditions are different. Globular pearlite is formed when the annealing temperature is low, and the very fine ferrite grain structure is appropriate at the annealing temperature and time is short form. After the cold-drawn steel is not annealed fine matrix structure is broken ferrite deformation, internal stress is large and easy to crack, so each drawing between system passes and finished pass after drawing system should be properly annealed recovery grow grains, eliminate stress. If the annealing time is short, the ferrite grains grow too late to recover, it will form a very fine ferrite grains. Under normal conditions the ferrite grain size is generally about 8, and the ferrite grain size of the fine is also finer than 10, the fine grains on the one hand to make a substantial increase in the strength of steel, and lead to plastic reduce. So the grain is too small, the elongation of steel is generally unacceptable.
Globular pearlite structure is a typical annealing inadequate organization. Normal cold drawing process requirements, the microstructure after annealing should be ferrite and pearlite flaky globular pearlite formation temperature is 750 ~ 830 °C, so the globular pearlite, suggesting that the low annealing temperature, annealing insufficient.
Extremely fine grains of ferrite is also an annealing inadequate organization, and its globular pearlite formation conditions are different. Globular pearlite is formed when the annealing temperature is low, and the very fine ferrite grain structure is appropriate at the annealing temperature and time is short form. After the cold-drawn steel is not annealed fine matrix structure is broken ferrite deformation, internal stress is large and easy to crack, so each drawing between system passes and finished pass after drawing system should be properly annealed recovery grow grains, eliminate stress. If the annealing time is short, the ferrite grains grow too late to recover, it will form a very fine ferrite grains. Under normal conditions the ferrite grain size is generally about 8, and the ferrite grain size of the fine is also finer than 10, the fine grains on the one hand to make a substantial increase in the strength of steel, and lead to plastic reduce. So the grain is too small, the elongation of steel is generally unacceptable.
订阅：
评论 (Atom)