Longitudinal and spiral welded pipe is the main difference between the two different production processes, first of all, the formation of straight seam welded pipe is the first through the molding machine to form hot rolled coil, making it into a cylindrical cylindrical outer surface, and then Welding, welding using the proximity effect or under the flux layer of the arc and skin effect, heating the edge of the tube and make it melt, in the appropriate extrusion cooling forming. Longitudinal submerged arc welded pipe and high-frequency straight seam welded pipe is different from the edge of the tube melting differentiate, the general use of arc melting is called the straight seam submerged arc welded pipe, high frequency straight seam welded pipe is the use of high frequency current melting. Spiral welded pipe production process is first in accordance with the appropriate angle of the spiral low-carbon structural steel and low carbon steel coil into the tube, and then welded seam molding. Spiral submerged arc welded pipe is the main form of spiral welded pipe. Can use the narrow steel billets to produce large diameter steel pipe is the most significant feature of the spiral pipe, widely used in all walks of life in China's gas pipeline construction.
To reduce the coating quality, layer type and the construction of environmental factors on the life of straight seam welded pipe coating life, regular welding of straight pipe to rust. Common methods of descaling are four, namely, pickling, cleaning, spray derusting and tool rust. Pickling is one of the most commonly used methods of derusting, not only as a reprocessing process after sand blasting, but also the surface of the straight seam welded pipe rust, oxide, worn coating completely removed, although this cleaning method can make steel surface roughness and cleanliness are up to standard requirements, but after all, is a chemical cleaning method, the surrounding environment is likely to cause pollution. Straight seam steel pipe cleaning can only be used as an auxiliary means in the anti-corrosion treatment, because the cleaning method can only steel surface dust, grease, and lubricants and other residual organic matter removed, and can not play a preservative effect, as we usually wash their hands , You can clean the surface of the dirt, most of the bacteria still remain in the hand. Professional and technical personnel with steel wire brush and other cleaning tools to polish the surface of the workpiece, this approach is called tool rust, loose rust, welding slag and oxide, etc. can be completely removed, but the steel surface attached to the solid Scale is powerless, can not achieve the standard anti-corrosion effect. Spray derusting is the use of steel grit, steel balls and other high-quality abrasive material through the jet strong centrifugal force to the surface of straight seam steel pipe to spray, not only can effectively remove the surface dirt, rust and oxides, roughness will be abrasive And the longitudinal welded pipe friction under the standard level.
2016年10月27日星期四
Straight Seam Welded Pipe Weld Flaw Detection Method
In order to detect the transverse or longitudinal defect of the weld of LSAW longitudinal seam, ultrasonic testing was carried out by jet (water column) coupling. Jet (water column) ultrasonic flaw detection is the probe and the pipe through the jet coupling between the probe issued by the longitudinal wave beam through the water or steel interface into the steel pipe, through the waveform conversion of the steel pipe welds pure shear wave detection.
Therefore, the realization of the weld in the pure shear wave detection, the probe angle of incidence must be between the critical angle and the critical angle between the II, can be derived from the law of refraction. The critical angles of the first and second critical angles of incident longitudinal waves from the water to steel are calculated to be 14.5 °and 27.3 °, respectively.
Longitudinal welded pipe Ultrasonic Inspection: Nondestructive testing is on-site testing, fast and non-destructive, without the need to arrive at the laboratory, greatly improving efficiency. The analysis speed is much faster than a benchtop spectrometer, and the results are displayed in seconds. Small size, light weight, easy to carry.
There are many kinds of nondestructive testing of ultrasonic flaw detection. The flaw detection principle of longitudinal seam welded pipe is not divided into: ultrasonic flaw detection, X-ray flaw detection and film flaw detection. Detection methods are: single-sided double-sided flaw detection, double-sided double-sided flaw detection, single-sided detection.
Therefore, the realization of the weld in the pure shear wave detection, the probe angle of incidence must be between the critical angle and the critical angle between the II, can be derived from the law of refraction. The critical angles of the first and second critical angles of incident longitudinal waves from the water to steel are calculated to be 14.5 °and 27.3 °, respectively.
Longitudinal welded pipe Ultrasonic Inspection: Nondestructive testing is on-site testing, fast and non-destructive, without the need to arrive at the laboratory, greatly improving efficiency. The analysis speed is much faster than a benchtop spectrometer, and the results are displayed in seconds. Small size, light weight, easy to carry.
There are many kinds of nondestructive testing of ultrasonic flaw detection. The flaw detection principle of longitudinal seam welded pipe is not divided into: ultrasonic flaw detection, X-ray flaw detection and film flaw detection. Detection methods are: single-sided double-sided flaw detection, double-sided double-sided flaw detection, single-sided detection.
2016年10月25日星期二
Anti-corrosion Measures of Oil Casing
Oil casing is the lifeline to maintain the normal operation of oil wells. Because of the different geological conditions, the stress state of the underground is complex, and the tensile, compressive, bending and torsional stresses act on the pipe body together, and the crude oil contains a lot of corrosive substances, and the oil casing is very easy to produce the corrosion. There are some anti-corrosion measures of oil casing following below:
1, Do a good job of water quality standards, strict water quality testing and management. The implementation of clean-up sub-injection, strengthening the main water pipe cleaning work, so that the station, the bottom of water quality standards, to reduce the introduction of corrosion space annular space.
2. Put into operation for the new injection wells, to take the main sterilization to vote for the ring to protect the liquid, and the formation of regular investment dosing.
3. In view of the mechanical abrasion to accelerate the role of corrosion of oil casing, it is recommended in the tubing coupling with a rubber ring or a serious deviation in the well plus a centralizer, to avoid the process and the process of water injection pipe casing and One side contact sleeve.
4. For serious bacteria corrosion and high temperature SRB slow growth and kill the situation, can be periodically injected into the annulus of 100 degrees Celsius high temperature water or water vapor to kill the SRB under the scale. Share from the Hebei Xin joint oil tube.
5. It is not recommended to promote cathodic protection and catalog casing before corrosion in the casing of injection wells is not effectively controlled.
6. You can brush the oil inside and outside the casing wall layer of anti-corrosion coating.
1, Do a good job of water quality standards, strict water quality testing and management. The implementation of clean-up sub-injection, strengthening the main water pipe cleaning work, so that the station, the bottom of water quality standards, to reduce the introduction of corrosion space annular space.
2. Put into operation for the new injection wells, to take the main sterilization to vote for the ring to protect the liquid, and the formation of regular investment dosing.
3. In view of the mechanical abrasion to accelerate the role of corrosion of oil casing, it is recommended in the tubing coupling with a rubber ring or a serious deviation in the well plus a centralizer, to avoid the process and the process of water injection pipe casing and One side contact sleeve.
4. For serious bacteria corrosion and high temperature SRB slow growth and kill the situation, can be periodically injected into the annulus of 100 degrees Celsius high temperature water or water vapor to kill the SRB under the scale. Share from the Hebei Xin joint oil tube.
5. It is not recommended to promote cathodic protection and catalog casing before corrosion in the casing of injection wells is not effectively controlled.
6. You can brush the oil inside and outside the casing wall layer of anti-corrosion coating.
Causes of Hot Rolling Cracks in N80Q Oil Casing
Hot-rolled seamless steel pipe production is one of the important processes, the rational development of its process plan or not, a direct impact on the size of the steel pipe after rolling the surface of the precision and quality,
Unreasonable process plan will cause the inner surface of the steel pipe to produce the defects such as folding, crack and concave.
N80Q steel casing is a standard oil casing commonly used in oil (for the seamless steel pipe), the standard provisions of the finished pipe heat treatment process for quenching and tempering.
N80Q casing production process is as follows: furnace refining → continuous casting → annular furnace → perforation → continuous rolling → stepping furnace → sizing → sawing → tempering treatment → straightening → physical and chemical testing → testing → thread processing → Coupling tight → water pressure test → measuring length weighing, marking → packaging storage. The billet was heated in an annular furnace for about 2.5 hours, perforated at about 1250 °C and then subjected to continuous rolling. The sintering temperature was 950 °C and the finish rolling temperature was 900 °C. The chemical composition of the tube from the test results can know the chemical composition of the tube is not the cause of the formation of cracks. From the metallographic, The results of EDS analysis show that both the crack tip and the middle part contain iron oxide inclusions. The crack is a non-quenching crack and should be produced before the heat treatment. This is probably caused by the perforation and hot rolling of the steel tube.
In the process of perforation of steel pipe, because temperature non-uniformity and uneven deformation have a large additional stress, the blank in the perforation easy to crack; And the heating temperature is too high, will also be due to reduce the intergranular binding force cracks; if the heating temperature is too low, due to lower plasticity, deformation resistance and deterioration of the perforation conditions, will also crack. In addition, the perforation process, due to the presence of additional deformation, when the billet surface will produce longitudinal shear stress and transverse shear shear stress. Therefore, there is a large lateral and longitudinal additional stress in the outer layer of the steel tube. In the case of non-uniform heating of the tube, when the superposition of the transverse basic stress and the additional tensile stress exceeds the intergranular bonding force, Small cracks, these cracks in the subsequent rolling and sizing process, along the rolling direction is elongated and extended to form the final crack. Therefore, in the future production should pay special attention to the perforation temperature, sizing temperature and finishing temperature of the monitoring and control, as far as possible the temperature fluctuations in the control within ± 20 ℃, and should increase the light tube end of the test strength, If necessary, increase the cut length of the pipe end.
N80Q casing pipe end crack is in the steel pipe perforation and rolling process; when the billet is hole, due to uneven heating temperature, at the same time in the transverse and longitudinal additional stress, resulting in crack formation and expansion.
It is suggested to adjust the process parameters of perforation and hot rolling in time, strengthen the control of the tube heating temperature, making the tube heating temperature fluctuations in a reasonable range.
Unreasonable process plan will cause the inner surface of the steel pipe to produce the defects such as folding, crack and concave.
N80Q steel casing is a standard oil casing commonly used in oil (for the seamless steel pipe), the standard provisions of the finished pipe heat treatment process for quenching and tempering.
N80Q casing production process is as follows: furnace refining → continuous casting → annular furnace → perforation → continuous rolling → stepping furnace → sizing → sawing → tempering treatment → straightening → physical and chemical testing → testing → thread processing → Coupling tight → water pressure test → measuring length weighing, marking → packaging storage. The billet was heated in an annular furnace for about 2.5 hours, perforated at about 1250 °C and then subjected to continuous rolling. The sintering temperature was 950 °C and the finish rolling temperature was 900 °C. The chemical composition of the tube from the test results can know the chemical composition of the tube is not the cause of the formation of cracks. From the metallographic, The results of EDS analysis show that both the crack tip and the middle part contain iron oxide inclusions. The crack is a non-quenching crack and should be produced before the heat treatment. This is probably caused by the perforation and hot rolling of the steel tube.
In the process of perforation of steel pipe, because temperature non-uniformity and uneven deformation have a large additional stress, the blank in the perforation easy to crack; And the heating temperature is too high, will also be due to reduce the intergranular binding force cracks; if the heating temperature is too low, due to lower plasticity, deformation resistance and deterioration of the perforation conditions, will also crack. In addition, the perforation process, due to the presence of additional deformation, when the billet surface will produce longitudinal shear stress and transverse shear shear stress. Therefore, there is a large lateral and longitudinal additional stress in the outer layer of the steel tube. In the case of non-uniform heating of the tube, when the superposition of the transverse basic stress and the additional tensile stress exceeds the intergranular bonding force, Small cracks, these cracks in the subsequent rolling and sizing process, along the rolling direction is elongated and extended to form the final crack. Therefore, in the future production should pay special attention to the perforation temperature, sizing temperature and finishing temperature of the monitoring and control, as far as possible the temperature fluctuations in the control within ± 20 ℃, and should increase the light tube end of the test strength, If necessary, increase the cut length of the pipe end.
N80Q casing pipe end crack is in the steel pipe perforation and rolling process; when the billet is hole, due to uneven heating temperature, at the same time in the transverse and longitudinal additional stress, resulting in crack formation and expansion.
It is suggested to adjust the process parameters of perforation and hot rolling in time, strengthen the control of the tube heating temperature, making the tube heating temperature fluctuations in a reasonable range.
订阅：
评论 (Atom)