LSAW Steel Pipe

　　In recent years, with the development of the national economy, thick-walled LSAW steel pipe have been increasingly used in offshore platforms, high-temperature and high-pressure vessels, and wind power pipe piles. The production of such steel pipes generally uses D36 steel, S355 steel and structural steel plates with Z-direction properties. The thickness of the plates is large, the carbon content is high, and the carbon equivalent is high. The weldability is poor, and the hardenability tends to be large. The welding performance of the joints is reduced, and cold cracks are easily generated, especially the transverse cracks are more likely to appear. After the occurrence of welding cracks, in addition to the necessary control measures, it is also necessary to pay attention to the timely repair of the workpiece. Taking S355 steel as an example to illustrate the repair measures after the occurrence of transverse cracks in welding. specifically is: 　　1, Confirming the defect 　　A 100...

　　The quality inspection method of lsaw steel pipe is as follows: 　　1, Judging from the surface, that is, in appearance inspection. The appearance inspection of welded joints is a simple and widely used inspection method. It is an important part of the inspection of finished products. It mainly finds the defects on the weld surface and the deviation in dimensions. It is usually visually inspected and tested with tools such as standard templates, gauges, and magnifiers. If the weld surface defects, there may be defects inside the weld. 　　2. Physical method inspection: The physical inspection method is a method that uses some physical phenomena to measure or test. Inspection of defects in materials or workpieces is generally performed by means of non-destructive testing. Non-destructive testing includes ultrasonic testing, ray testing, penetrant testing, and magnetic testing. 　　3, The strength of the pressure vessel inspection: pressure vessel, in addition to the sealing test, but...

　　 LSAW welding of laser welding machine is an automatic welding equipment that automatically completes the straight weld seam of the welding workpiece through automation and mechanization. Straight seam welder is also called straight seam automatic welder, and longitudinal seam automatic welder is a kind of automatic welder. It can replace large amounts of manpower, greatly increase production efficiency and welding quality, reduce labor costs, and improve the welding workers' working environment. Such as large-scale transformer shell corner seam welding, large barrel straight seam welding, solar water heater barrel straight seam welding, production line belt straight seam welding, H-beam welding, etc., are a large number of straight seam welding machine. Features of lsaw welding of laser welding machine: 　　 1, Power 　　The average laser power is 300W, and the maximum power at work can reach about 400W, which is higher than that of other companies. When the laser welding machi...

　　Features of lsaw steel pipe structure in design are as follows: 　　(1) The geometrical characteristics of the pipe section are good, the pipe wall is generally thin, the cross-section material is distributed around the centroid, the radius of rotation of the cross-section is large, and it has strong torsional rigidity; as a member subjected to compression, bending and bi-directional bending, The bearing capacity is higher, and the accuracy of flatness and cross-sectional dimensions of the cold-formed pipe is better than that of the hot-rolled opening. 　　(2) In terms of anti-hydrodynamic properties, the cross-section of the circular pipe is the best, and the effect of wind and water flow is greatly reduced. Rectangular tube sections are similar in this respect to other open sections. 　　(3) The steel pipe is a closed section; in the case of the same average thickness and cross-sectional area, the exposed surface area is approximately 50% to 60% of the open section, which is benef...

　　It can destroy the ingot casting structure, refine the grain of the steel, and eliminate the defects of the microstructure, so that the steel structure is dense and the mechanical properties are improved. This improvement is mainly reflected in the rolling direction, so that the lsaw steel pipe is no longer an isotropic body to a certain extent; bubbles, cracks and looseness formed during pouring can also be welded under high temperature and pressure. 　 　Disadvantages of lsaw steel pipe 　　1. Residual stress caused by uneven cooling. Residual stress is the stress of internal self-phase equilibrium under no external force. Hot rolled steel of various sections has such residual stress. The larger the section size of general steel, the greater the residual stress. Although the residual stress is self-balanced, it still has some influence on the performance of steel components under external forces. For example, it may have adverse effects on deformation, stability, and fatigue resis...

　　 Galvanized pipe is usually used for indoor water supply. Outdoor water supply pipes are usually laid at <0.7m depth and must be below the local freezing line. Working pressure <0.6MPa. 　　Installation requirements of galvanized water pipe: 　　(1) The pipes, fittings and connecting methods for pipelines, pipe fittings and connecting pipelines for firefighting and domestic water sharing must comply with the design requirements or the construction specifications; pipes and pipe fittings shall be galvanized with all pipe walls and shall not be non-galvanized or galvanized only, Galvanized inside the pipe, pipe fittings used in domestic water supply pipe. 　　(2) Where the galvanized pipe used for water supply is connected with the pipe fittings, it shall be connected by means of threaded fasteners and welded connections shall not be used. Otherwise, the galvanized layer will be damaged or the inner diameter of the small pipe will be blocked by the welding torch. 　　(3) Prior t...

　　We all know that 304 stainless steel pipe for pressure pipe components, for the production of relatively high demand, the general cold forming temperatures are not up to the production requirements, so the need for 304 stainless steel pipe heat treatment process, the industry collectively referred to as solution treatment. To achieve the heat treatment process is divided into the following steps: 　　1.304 stainless steel heat treatment - annealing 　　The stainless steel tube heated to a certain temperature and heat for a period of time, and then make it slowly cooling, called annealing. Steel annealing is the steel heated to a phase change or partial phase transition temperature, after cooling slowly cooling after the heat treatment method. 　　2.304 stainless steel heat treatment - normalizing 　　Normalizing is the heating of stainless steel to a critical temperature above, so that all stainless steel into uniform austenite, and then naturally cooled in air heat treatment. It ca...

　　In our current society, steel pipes are used in many fields. Steel pipes are used in transportation, construction and other aspects. Nowadays, a large number of steel pipes are roughly divided into two types. One is a seamless steel pipe and the other is a seamed steel pipe, like ssaw steel pipe. Although all are steel pipes, seamless steel pipes are much stronger than seamed steel pipes in any aspect. Therefore, the steel pipes used are all seamless steel pipes, and the use of it will have many advantages. Now it is occupied by the steel pipe industry a lot of markets. 　　The reason why it can become the first choice for people to choose steel pipe is because of the various advantages of itself, such as good precision, light weight, good compressive ability, etc. The use of what can be used in all areas is very good, precisely because of the very good precision, so now in the transport are used in the seamless steel pipe in the cold-drawn steel. Seamless steel tubes and alloy tubes...

　　① Flange pressure contact surface should be gold processing, in order to prevent welding deformation, flange contact surface depth should be recessed into h = (0.10 ~ 0.20) t, to provide the amount of deformation. 　　② Steel pipe intersecting line weld seam fillet weld, multi-layer welding, welding should be continuous, each weld surface should be promptly cleaned, if found to be defective in quality, should be eradicated after welding. 　　③ Flange pressure contact surface unevenness should be less than or equal to ± 0.20mm, in order to ensure the flange connection, the contact surface fit rate greater than or equal to 75%, with 0.4mm feeler inspection, the depth of the insertion area and the sum of not more than 25% of the total area, the maximum connection gap shall not be greater than 0.8mm. 　　④ Outer diameter of flange plate machining ovality less than or equal to 0.03 ~ 0.1mm (according to 11 tolerances) considering the influence of oval tolerance of steel pipe, flange diam...

　　Welded neck flange generally use forging or forging process is made. Elected with steel or steel production, it is necessary to meet the following requirements: 　　1. Welded neck flange should be ultrasonic flaw detection, no delamination defects; 　　2. Should be cut along the direction of the steel strip into a bar, butt welded into a ring, and the surface of the steel ring cylinder. Shall not be machined directly into the plate with a neck welded flange; 　　3. Ring butt weld should be used fully welded weld; 　　4. Ring butt weld should be post-weld heat treatment, and for 100% ray or ultrasonic flaw detection and ray inspection meet JB4730 class II requirements, ultrasonic flaw detection meet JB4730 class I requirements.

　　Stainless steel is different from the main symbol of carbon steel is in addition to carbon content, no other people to join other alloying elements. Carbon steel generally do not have any corrosion resistance, hardness than pure iron, of course, carbon is also controlled to a certain extent. 　　Many types of stainless steel, refers to the amount of steel is greater than or equal to 13%, in the atmosphere of stainless steel alloy. There are austenitic stainless steel, ferritic stainless steel, martensitic stainless steel and so on. Stainless steel generally does not have magnetic, but not absolute, austenite is not magnetic, but ferritic has, but also relatively weak. Different stainless steel resistance to corrosion is different, different corrosive to different media. 　　Regarding the difference carbon steel and stainless steel, generally believed that the first is in terms of corrosion resistance. However, stainless steel in practical applications, with its excellent performance,...

　　316L stainless steel pipe if it contains impurities, not only its surface quality, the impact of its performance is immeasurable. And if want to reduce the 316L stainless steel pipe impurities, improve its purity, it is necessary to start from the production process. The following is to improve the purity of 316L stainless steel pipe method. 　　1, To avoid impurities into the steel. 　　a. Manufacturers in the procurement of raw materials (scrap, ferroalloy, etc.), slagging information (lime, fluorite, etc.), deoxidized data quality and baking, boring; 　　b. Stainless steel pipe manufacturers of steel-making workshop lining, ladle and pouring system with the quality of refractory materials and baking; 　　c. Progressive steelmaking gas (argon, oxygen, nitrogen, etc.) purity (can not have water, etc.); 　　d. Avoid secondary oxidation of molten steel during tapping and pouring. 　　2, Removed from the steel. Manufacturers in the production of the method is selected AOD, VOD and oth...

　　1. Plasticity: plasticity refers to the metal material under the action of the load, resulting in plastic deformation (permanent deformation) without breaking the ability. 　　2. Hardness: hardness is a measure of the degree of hardness of metal materials. The most commonly used in the production of hardness measurement method is the pressure hardness method, it is a certain geometric shape of the indenter under a certain load into the test of stainless steel pipe surface of the metal, according to the degree of penetration to determine the hardness value (commonly used methods are brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC) and vickers hardness (HV) and other methods. 　　3. Fatigue: The strength, plasticity, and hardness discussed above are the mechanical properties of the metal under static load. In fact, many machine parts are working under cyclic loading, under which the parts will produce fatigue. 　　4. Impact toughness: the load acting on the machine at very lar...

　　 First, the magnetic test 　　The magnetic test is the simplest way to distinguish between annealed austenitic stainless steel and ferritic stainless steel. Austenitic stainless steel is non-magnetic steel, but by the cold down after cold processing will have a mild magnetic; and pure chrome steel and low alloy steel are strong magnetic steel. 　　 Second, nitric acid point test 　　One of the salient features of stainless steel welded pipes is the inherent corrosion resistance of concentrated nitric acid and dilute nitric acid. This performance makes it easy to distinguish from most other metals or alloys. But the high-carbon type 420 and 440 steel in the nitric acid point test is slightly corroded, non-ferrous metals encountered concentrated nitric acid will be corroded immediately. The dilute nitric acid on the carbon steel has a strong corrosive. 　　 Third, the copper sulfate point test 　　The copper sulfate point test is the easiest way to quickly distinguish between ordinary...

　　There are many types of electric resistance welding(erw), and there are three types of welding, seam welding, butt welding and projection welding. 　　First, spot welding 　　Spot welding is a method of electric resistance welding in which a weldment is assembled into a lap joint and pressed between two columnar electrodes to melt the base metal by electric resistance to form a solder joint. Spot welding is mainly used for thin plate welding. 　　Spot welding process: 　　1. Preloading to ensure good contact with the workpiece. 　　2. Power on, so that the weld is formed into a nugget and a plastic ring. 　　3. Power-off forging, so that the nugget cools and crystallizes under the pressure, and forms a welded joint with dense structure, no shrinkage hole and crack. 　　Second, seam welding 　　Seam welding is mainly used for welding welds that are relatively regular and require sealing. The thickness of the joint is generally less than 3 mm. 　　Third, butt welding 　　Butt welding i...