In the long-distance transmission of natural gas, the pipeline in the deep sea under the pressure of resistance to external water pressure, so the general use of UOE pipe. UOE steel pipe manufacturing methods for the cold stamping method, the strength of steel anisotropy. In order to predict the compressive strength of UOE steel pipe and to find out the crushing mechanism of the steel pipe, Nippon Steel has carried on the numerical simulation analysis of steel pipe forming-performance evaluation. The numerical simulation is composed of two-dimensional forming model of steel pipe and three-dimensional crushing model of steel pipe which reflects the shape and residual stress. 1. Strength anisotropy and residual atress of UOE steel As we all know, the factors that affect the compressive strength of steel pipe shape (pipe roundness and uneven wall thickness), yield strength (YS) and residual stress. The compressive yield strength in the circumferential direction and the residual stress have a great relationship with each other. The yield strength distributions of the wall sections measured for round bars and cylindrical specimens (both 6 mm in diameter) show that the decrease in the compressive yield strength in the circumferential direction of the steel pipe is particularly pronounced. The comparison of the S-S curves in the wall thickness position shows that a circular S-S curve originates from the wall thickness center and externally due to the Bauschinger effect of elastic deformation. According to the comparison of UOE steel pipe and seamless steel pipe for oil well, the residual stress of the two kinds of steel pipe tends to be compressed inside, but the residual stress of UOE steel pipe is small. 2. Numerical simulation In the process of numerical analysis, an integrated model was used to evaluate the forming-compressive strength of UOE steel tubes. In the forming model of the UOE steel pipe (two-dimensional plane deformation element), the S-S curve of the plate is used and the residual stress is applied to the crush model (three-dimensional solid element). The semi-experimental method (simulated deformation test) is used to predict the S-S curve because it is difficult to precisely predict the S-S curve change from plate to steel pipe only by numerical analysis and simulation. That is, the calculated equivalent plastic strain hysteresis is applied to the rod sample sampled from the plate, and then the compressed S-S curve obtained for each wall thickness position is defined.

This is a modern long-distance pipeline transportation industry, the most basic transport pipeline, thick-walled seamless steel pipe because the wall thicker in the field has a strong anti-collision, corrosion-resistant nature, in the long-distance oil, and natural gas transport has been an irreplaceable role, although the field of modern pipeline transportation are in use, but the installation is always a big problem. Pipeline there are joint place, here is the focus of the installation, such as pipe wall with thick, almost no management way of some environmental problems, usually directly after digging a hole big enough to accommodate pipe, directly put into the pipeline, but where the joint will note that this is the place where the test technology of the workers. Commonly used in the production of thick wall seamless steel tube has been ready to joint work, each type of pipe has its own unique bolt, if the use of forced some pipeline model does not match, will not only affect the pipe, at the same time in the process of transportation may be compromised.

Spiral steel pipe plant in the production process will encounter this question, because the composition of different types of steel, their transition temperature, transition time and the characteristics of the study the same. Even if the same steel, only the end is not the same use, the needs of the arrangements and functions are not the same.   The secondary cooling means cooling from the temperature at the beginning of the phase transformation to the temperature at which the phase transition is completed. The purpose of the secondary cooling is to control the phase change process by controlling the cooling rate during the phase change and stopping the temperature control to ensure the required metallographic arrangement after the steel is rapidly cooled.   Secondary cooling (air cooling) refers to the phase change to room temperature range of cooling. On the shop in the air-cooled process will occur in the separation of carbonitride, the resulting bainite tempering occurred. On the high-carbon steel or high carbon steel alloy steel phase transformation after the air-cooled, will make the fast cooling, the separation of the super-saturated carbide dispersion continued separation. Such as the phase change is still selected after the completion of technology, you can hinder the carbide separation, adhere to the carbide solid solution, solid solution to strengthen the intention.

Spiral pipe for liquid delivery with: water supply, drainage. For gas transportation with: gas, steam, liquefied petroleum gas. Petrochemical industry, chemical industry, electric power industry, agricultural irrigation, urban construction, is the development of China's 20 key products (such as water supply, water supply, water supply and drainage). There are several types of fracture of the spiral tube, according to the situation after the destruction of materials corrosion steel pipe and metal material fracture is roughly the same type is divided into three types, namely: ① cleavage fracture, ② hole reverse fracture, ③ slip surface Separation fracture. Cleavage fracture of the cross-section of a crystal in strict accordance with the separation, the crystal surface known as the cleavage plane. The fracture strength along this plane is the lowest, and is determined by equation (1-4). The factors that determine the cleavage plane are the specific surface energy y, the interplanar distance of the crystal plane, and the elastic modulus along the normal direction. Cleavage fracture is almost not accompanied by plastic deformation, is a brittle fracture, in the body-centered cubic, closely packed hexagonal gold center. Face-centered cubic metals generally do not undergo cleavage fracture. The shear fracture is the main fracture mechanism of the ductile material. Such as anti-corrosion steel alloy in the second phase of the particles from the role of blocking the slip, increasing resistance to plastic deformation; when the plastic deformation increases, the second phase particles and substrate interface occurs stripping Ang, a small hole; Forming, growing up and merging will form a shear section. For high-purity metal, the absence of second-phase particles, bimetallic wear-resistant composite pipe and therefore will not produce: tiny holes, the result of moving along only the surface area is increasing, and finally form a sliding surface separation section. Anti-corrosion steel pipe spinning compound technology is precisely under the special control of special equipment, the pressure roller rotation and lined tube friction to produce heat, quickly reach the softening point of stainless steel, squeezing the outer extrusion tube to the elastic deformation, the two produce interference Cooperation, to achieve close integration. From the perspective of the organization of the gold, the fracture is divided into transgranular fracture and fracture along the goods.

1. High-frequency resistance welding By using the skin effect and the proximity effect of the high-frequency current, the edge of the steel strip strip is rapidly heated to a molten state, and the molten metal is extruded under the action of the squeezing roller to realize the welding. 2. Submerged arc welding Welding arc a method of performing arc welding under the coverage of a flux. Welded metal pool in the solder layer under the protection of solidification into the weld, flux melting layer cooling for the slag shell covering the outer surface of the weld. 3. Tungsten inert gas shielded welding (TIG) The use of pure tungsten or activated tungsten (thorium tungsten, cerium tungsten, etc.) as the electrode inert gas shielded welding into tungsten inert gas shielded welding, the English referred to as TIG welding. It is under the protection of the inert gas, the use of tungsten electrode and the arc generated between the welding material and hot melt filler metal welding wire welding method. 4. MMA welding of molten inert gas (GMAW) The use of welding wire for the melting electrode inert gas shielded welding. 5.CO2 gas welding protection Gas - shielded arc welding of gas with purity> 99.8% CO2. 6. Mixed gas shielded welding By two or more gases, according to a certain percentage of the composition of the gas mixture as a protective gas shielded welding. TIG: Gas shielded arc welding using argon as the shielding gas. 7. Pulse argon arc welding Using the base current to maintain the main arc of the ionization channel, and periodically add a high pulse current with a high peak pulse current to melt the metal and control the transfer of molten argon welding. 8. Plasma arc welding by means of water-cooled nozzle of the role of the binding of the arc to obtain a higher energy density of the plasma arc welding method. 9. In the process of hot-brazing welding, a metal material having a lower melting point than that of the base metal is used as the brazing filler metal to heat the brazing filler metal and the brazing filler metal to a temperature higher than the melting point of the brazing filler metal, state solder wetting base metal, fill the gap and the inter-diffusion with the base material to achieve the method of welding parts called brazing. Commonly used composite steel brazing method for induction brazing.