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San-RamonDN25 Various treatments are summarized as follows: high temperature oxidation method is to immerse the workpiece in a specific molten salt and maintain a fixed process temperature
Preheating must be carried out before heat treatment of q355b square tube, so as to better ensure that there will be no many problems in the whole heat treatment process of q355b square tube, and the quality of q355b square tube will also be well guaranteed.
AsAb.The other is designed with deformation angle, which can be regarded as 180 DEG from round tube to square tube; To 90 & deg; The bending deformation of angle, so the deformation angle & theta; It can accurately reflect the deformation degree of corners and edges. In the design process, considering the influence of dimensional accuracy and metal work hardening, the distribution of deformation angle is usually larger at the beginning and middle passes, and then gradually decreases. In the pass formed directly by arc intersection, the fillet part of the pipe blank cannot be filled with the pass, so the pass perimeter is different from that of the pipe blank. In order to ensure the dimensional accuracy, the fillet part of the pass needs to be corrected and calculated. Therefore, this method has higher design accuracy than other methods. However, due to the large amount of iterative calculation, this method is more suitable for pass design by computer. If you use a frame that deforms both horizontally and vertically, you can directly use the deformation angle & theta; Pass design.
HDPE plastic square pipe made according to the properties of square pipe has the advantages of light texture, high strength, good resistance, easy laying, low water resistance, low cost and corrosion resistance. Its service performance and economic benefits far exceed reinforced concrete pipe and general specification iron pipe. It is an updated product of engineering pipe.
.One of the steps that are prone to defects in the production of square tubes is heat treatment and the other is tensile treatment. Today we need to know the latter. Maybe some people will have a lot of questions about why square tubes are prone to defects in tensile. Now let's analyze the specific causes of defects.
Process flow of square tube drawing: because the size of the die hole of the square tube drawing is smaller than the outer diameter of the tube in front of the drawing, in order to make the front end of the square tube pass through the die hole smoothly, so that the clamp jaw of the drawing trolley can the head of the square tube, it is necessary to sharpen the head of the square tube before drawing. Therefore, the end of the square tube with a fixed length should be heated in the slit heating furnace, It is generally 150 ~ 200mm and the heating temperature is between 750 ~ 900 ℃ according to different wall thickness. Then use 75 ~ 300kg air hammer to sharpen and grind the head of the square pipe. Generally, the square pipe with diameter less than 22mm can be sharpened by rotary forging hammer or roll forging machine.
The welding sequence is to reduce deformation. The welding sequence of rectangular butt welding shall adopt layered and symmetrical skip welding from the middle to both sides according to the following principles. The welding deformation is smaller than that of straight through welding, which is conducive to the dispersion and release of stress and avoid complex stress in weldments. During straight through welding, the narrow plastic deformation zone formed at the beginning of welding only occurs once. Moreover, due to continuous welding, the heating area is large and the plastic deformation area caused by compression is large, so the shrinkage deformation after welding is very large. In case of layered and segmented skip welding, the section of each layer is very small, and the heat required is small, and each layer is divided into several sections for skip welding. Each welding section basically re establishes the secondary temperature field on the cold steel plate, and a narrow plastic deformation zone appears each time. Therefore, the average width of the plastic deformation zone (i.e. the size of transverse shrinkage) is smaller than that of the corresponding layered straight through welding, and the longitudinal shrinkage is also smaller, The welding deformation is smaller than that of continuous filling.
Square tubes are more and more widely used in practice. Different types of square tubes have different characteristics, so as to improve its work efficiency. Next, let's introduce what should be paid attention to when heating the lower tube.
Derusting: This is an important process for galvanized square pipes and components before coating and it is the key to the quality of galvanized square pipes. Thorough derusting can improve the adhesion of antirust paint and prolong the service life of galvanized square pipe.
Spray fluorocarbon paint after.
Range.Reach or even exceed the level of resistance welding cold formed square pipe. The size of R angle is generally between 2-3 times of the wall thickness. R angle square pipe of the size required by customers can also be produced according to customers' needs; Square pipe is a kind of long steel with hollow section and no joints around. It is a square pipe formed by four sides of seamless pipe mold. Square pipe has hollow section, professional square pipe, square rectangular pipe, seamless square pipe, galvanized square pipe, galvanized square pipe, strict inspection and quality assurance. The preferential activity is in progress. Welcome to consult. A large number of pipes are used for conveying fluid. They are mainly used in conveying, hydraulic support and mechanical structure, Medium and low pressure, high pressure boiler tubes, heat exchange tubes, gas, oil and other industries. It is stronger than welded and will not crack.
The test can be carried out under cold and hot conditions. If the test temperature is not specified,AsAbGalvanized water pipe, the test shall be carried out under normal temperature, but not lower than - 10 ℃.
During the storage of square tubes, resulting in radial plastic deformation and layer damage of square tubes. It is recommended that the stacking layers of smooth pipes refer to apirp 5l1-2009 Recommended Practice for railway transportation of square pipes for pipelines or apirp 5lw-2009 Recommended Practice for ship and sea vessel transportation of square pipes for pipelines. It can also be determined by test or implemented according to the safe stacking height of square pipes. The stacking layers of pipes shall be implemented according to GBT 23257-2009 polyethylene layer of buried steel pipelines.
The painting of the square tube has to go through a process, which requires us to conduct comprehensive consideration and analysis. In particular, the quality and level of the paint and the relevant technical level deserve our attention. Note that the square tube should not be used immediately after painting, but should be placed for a period of time and wait until the paint is dry!
manufacturer.The surface compressive stress characteristics of the square tube will be obtained after isothermal quenching.
Section shape classification square tubes are classified according to section shape: simple section square tubes & mdash& mdash; Square tube, rectangular tube and complex section square tube & mdash& mdash; Surface treatment classification of flower shaped square pipe, open square pipe corrugated square pipe and special-shaped square pipe square pipe is divided into hot-dip galvanized square pipe, electro galvanized square pipe oil coated square pipe and pickling square pipe according to surface treatment. Square pipe is classified according to purpose & mdash& mdash; Square tubes for decoration, machine tools and equipment, machinery industry, chemical industry, steel structure, shipbuilding, automobile, steel beam and column and special purpose are classified by wall thickness & mdash& mdash; Super square tube, square tube and thin-walled square tube plasticity refers to the ability of metal materials to produce plastic deformation (deformation) without deformation under load.
It is a kind of cleaning for the surface of square pipe. Shot blasting is often used to clean the casting surface or strengthen the surface of square pipe.
AsAb.Dimensional stability for high-precision square tubes, the required accuracy is high, so the dimensional stability must be maintained. Due to straightening in the air and slow cooling speed, it has the effect of stabilization and will increase the number of residual square tubes in the, so it must be cooled; Reduce quenching deformation because the square tube is slender, it is easy to deform during quenching, so its deformation must be strictly controlled. Heat treatment is a key process. In the process of quenching and cooling, the cold plasticity shall be corrected in time, which is a key step to ensure the improvement of its qualification rate. Therefore, hot bath quenching or cooling in oil for a fixed time shall be carried out to propose thermal correction.
At present, there is still a lack of research on surface adhesion, there is no systematic and perfect theory to guide the preparation of anti adhesion inner surface of pipeline,AsAbQ345B straight seam rectangular tube, and there is a lack of operable and low-cost inner surface preparation technology of square pipe. In terms of solid surface adhesion mechanism,AsAbSpecification and model of galvanized flat pipe, this paper analyzes the spreading process on machined rough surface, studies the dynamic movement characteristics of solid-liquid vapor phase line, directly analyzes the adhesion process, and establishes a line spreading model based on small system energy, It provides theoretical guidance for the preparation of anti adhesion surface of pipeline.
It is forbidden to degrease the oil square pipes and pipe fittings in the direct production concentration unit, air separation unit, oil refining and chemical engineering according to the design requirements. The purpose of degreasing is to prevent the transported or stored materials from being contaminated by grease or organic matter; Avoid mixing transported or stored materials with grease or organic matter; Oil content to ensure the activity of the catalyst; The content of oil and organic matter to ensure the purity of the product. The installed square pipe shall be disassembled into pipe sections for degreasing. Pipes that cannot be disassembled after installation shall be degreased before installation. Square pipes with obvious oil stains or serious corrosion shall be cleaned by steam purging, sand blasting or other methods before degreasing.