Difference between ERW straight seam electric resistance welded steel pipe and LSAW (UOE) steel pipe: First, the difference between raw materials and production capacity ERW steel pipe material is hot-rolled steel coils, raw material UOE steel pipe is hot rolled steel sheet. Therefore, ERW steel pipe can achieve a continuous pipeline operations, high production efficiency, low production costs; and UOE steel pipe with a steel plate processing, can not achieve continuous pipeline operations, production efficiency is low, high production costs. Restricted ERW steel pipe coil thickness, the maximum thickness is producible 25mm, to produce a maximum diameter of 660mm; UOE steel pipe produce the maximum thickness of 40mm, the steel sheet to produce the maximum diameter is limited only by the width of the currently available produce the maximum diameter of 1422mm. Second, the difference between welding ERW pipe welding without adding wire; UOE need to add steel wire. Third, the appearance difference ERW steel inside and outside welds required to be removed, so the corrosion favorable; UOE Pipe Wall Weld stay more than a high anti-corrosion disadvantage. Fourth, the difference between the purchase cost and the difficulty of ERW steel pipe low purchase cost, UOE steel pipe cost is very high, generally spread is 15% -25%. Domestic UOE steel manufacturers less, purchasing high degree of difficulty. When the diameter <Φ406mm, the greater the difference between the purchase cost. ERW steel pipe manufacturers are more difficult to purchase low, when the diameter of <when Φ406mm, will mate was reduced procurement costs. Five, Application difference ERW steel pipes are mainly used in natural gas, refined oil, crude oil, pulp and other terrestrial long-distance pipelines. UOE steel pipes are mainly used in high-voltage submarine long-distance pipelines, cold areas, land two, three, four types of regions.

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.

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.

(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.

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