steel tube

　　What should I pay attention to when welding seamless steel pipe? The following is the explanation of the staff of seamless steel pipe manufacturer, I hope to help you. 　　1. When the butt is bottomed, in order to prevent the back side of the bottom bead from being oxidized, gas protection is also required on the back side. 　　2. In order to prevent the occurrence of the welding holes of the special-shaped pipe, the welding parts must be cleaned if there is rust or oil. 　　3. Dry elongation, the general welding current is about 5mm when the temperature is below 250A, about 20-25mm above 250A is more suitable. 　　4. It adopts flat characteristic welding power source, and reverse polarity is used for DC welding. The welding can be carried out using a general CO2 welder, but the pressure of the wire feed wheel should be slightly loosened. 　　5. Arc length, MIG welding of stainless steel shaped tube, generally under the conditions of jet transition welding, the voltage should be adju...

　　Generally speaking, all the galvanized steel tubes , no matter they are hot dipped or cold dipped, cannot be welded to be welded steel tubes. However, everything has an exception. For the galvanized steel tubes with an OD of more than 100mm, the connection shall be flannel or coupler and the joints between the galvanized scaffolding tube and the flannel shall be processed with a second time of galvanization. 　　The welded steel tubes, especially the stainless ones, can be widely used in the steel concrete projects. The reason is that the steel tubes can be used to improve the concrete strength and its capacity in fighting against the harsh marine environment when the stainless steel concrete is used on the bridges of many coastal buildings, such as the Coosbay Bridge, which has a higher requirement on the anti-erosion degree and the seismic-proof ratio. When compared with normal carbon steels, the stainless welded steel products have better comprehensive properties and longer workin...

　　There is a long history for all the scaffolding products used in the building construction projects, so does the steel pipes. 　　The use of the steel pipes can be dated back to 1930s, such as the London Savory Hotel built in 1929, which used the steel pipes to decoration the roof and the hotel wall. It maintains an outstandingly beautiful outlook for 70 years in such a polluted environment along the coast. Another one is the US Chrysler Building built in 1930, which also used the steel pipes on the roof and in the wall decoration. It still towers a brilliant glow among all the building groups in NY even though it had been washed for only two times. 　　With the accelerating speed in improving the living standard and economy, the advantages of the scaffolding tubes are well recognized by the populace, including its durability, the aesthetics, the long working time and the cost effectiveness. And the application ranges of it span from the industry of decoration, roofing, steel concre...

　　Below 480°C, the zinc solution dissolves slowly on the matrix iron. When the temperature of the zinc solution is 430-480°C, the iron loss changes with time according to the parabolic law. Within this temperature range, the resulting alloy is dense and continuous. Therefore, the general hot-dip galvanizing temperature is controlled at about 450 °C. The temperature of 495 °C is the malignant dissolution temperature of zinc to iron. At this time, the coating is loose and is the forbidden zone of hot-dip galvanizing. When the temperature of zinc solution is 490-530 °C, the iron loss has a linear relationship with time. When the temperature of the zinc solution is above 530 °C (up to 580 °C), the reaction returns to the parabolic law. At about 540 °C, the zinc solution has a strong dissolving power for iron and can be used for gray iron castings. However, the higher the temperature, the greater the bonding ability of zinc and iron, the faster the alloy reacts, and the fluidity of zinc liq...

　　The tempering process of the casing pipe is a heat treatment process of reheating the quenched workpiece to a suitable temperature lower than the lower critical temperature, and cooling to room temperature in a medium such as air or water or oil after a certain period of time. 　　The purpose of tempering: 　　(1) To eliminate the residual stress generated during quenching of the workpiece to prevent deformation and cracking; 　　(2) To adjust the hardness, strength, ductility and toughness of the workpiece to meet the performance requirements; 　　(3) To stabilize the structure and size, to ensure Accuracy; 　　(4) Improve and improve processing performance. 　　The tempering category of oil casing pipes: 　　1. Low temperature tempering meaning: refers to the tempering of the workpiece at 150~250 °C. 　　Objective: To maintain the high hardness and wear resistance of the quenched workpiece and reduce the quench residual stress and brittleness. After tempering, tempered martensite i...