Before the jet treatment, the grease and fouling of the surface of the alloy pipe are removed, and the pipe body can be preheated to 40-60 degrees celsius by a heating furnace to keep the surface of the alloy pipe dry, the original degree of corrosion, the required surface roughness degree, the type of coating to choose abrasive, single-layer epoxy, two or three polyethylene coating, in order to achieve the desired effect of rust, alloy steel tube and steel shot need to use mixed abrasive. Because the steel shot has the effect of strengthening the steel surface, steel sand has the role of etching the steel surface.   Alloy tube want to get better uniformity of cleanliness and roughness of the distribution, the abrasive particle size and proportion design is very important,because the roughness is too easy to cause corrosion in the anchor thinning at the peak, At the same time, because the anchor pattern is too deep, it is easy to form bubbles in the process of corrosion, a serious impact on the performance of the coating. Because the alloy pipe surface is free of grease and other dirt, which can enhance the effect of rust, in addition, the dry alloy pipe surface is also conducive to steel shot, grit and rust and oxide skin separation, Rust after the alloy tube surface is more clean.   Alloy tube before plating stress and after the hydrogen plating to eliminate hydrogen embrittlement if the parts by quenching, welding and other processes after the internal residual stress larger, should be tempered before plating, tempering to eliminate stress can actually reduce the parts of the The number of traps, alloy tubes to reduce the risk of occurrence of hydrogen embrittlement. Therefore, hardness <32HRC of the fasteners, alloy tube coating thickness can be required in 12μm; hardness ≥ 32HRC high-strength bolts, coating thickness should be controlled at 8μmmax. This requires product design, we must take into account the high-strength bolts of hydrogen embrittlement risk, a reasonable choice coating species.

1, Hot extrusion method: the need for pre-extrusion processing of blank pre-treatment, when the extrusion diameter of 100mm below the pipe, the equipment into small, less waste of materials, technology is more mature. However, once the pipe diameter size increases, the use of hot extrusion method requires large tonnage and high-power equipment, the corresponding control system should be upgraded. 2, Hot piercing rolling method: hot piercing rolling rolling and rolling to extend the main extension. Rolling and rolling of continuous mandrel bar, continuous rolling of mandrel bar, rolling of mandrel bar, rolling of mandrel bar and rolling of mandrel mill. These methods have high production efficiency, low metal consumption, good product quality, advanced control system and wide application. The skew rolling method has the advantages of low investment, short process, suitable for small batch, multi-variety, multi-specification and high-precision middle and thick-walled seamless pipe production and also has been widely used. 3, Hot push system expansion method: push system expansion equipment is simple, low cost, easy maintenance, economic and durable, flexible product specifications change, such as the need to prepare large diameter elbow and similar products, only need to add some accessories. Suitable for the production of thin-walled thick-walled steel pipe, can also produce equipment does not exceed the capacity of thick-walled tube.

1, Usually length The normal length of the steel pipe should be 3000MM-12000MM. 2, Cut length Length of steel pipe should be within the length of the normal length of straight seam high-frequency electrical resistance welded steel pipe length of the length of the allowable deviation of +200 MM; spiral submerged arc welded pipe length of the length of the permissible deviation +500 MM. 3, Double length The total length of double-length steel pipe should be within the normal length, straight seam high-frequency electrical resistance welded steel pipe the total length of the permissible deviation of +200 MM; spiral submerged arc welded steel pipe the total length of the permissible deviation of +500 MM, Leaving 5MM-15MM of the incision margin. 4, According to the demand side, the supply and demand sides in consultation, and specify in the contract, can supply the length of the length of the length of the length and length of the length of the steel pipe.

Longitudinal and spiral welded pipe is the main difference between the two different production processes, first of all, the formation of straight seam welded pipe is the first through the molding machine to form hot rolled coil, making it into a cylindrical cylindrical outer surface, and then Welding, welding using the proximity effect or under the flux layer of the arc and skin effect, heating the edge of the tube and make it melt, in the appropriate extrusion cooling forming. Longitudinal submerged arc welded pipe and high-frequency straight seam welded pipe is different from the edge of the tube melting differentiate, the general use of arc melting is called the straight seam submerged arc welded pipe, high frequency straight seam welded pipe is the use of high frequency current melting. Spiral welded pipe production process is first in accordance with the appropriate angle of the spiral low-carbon structural steel and low carbon steel coil into the tube, and then welded seam molding. Spiral submerged arc welded pipe is the main form of spiral welded pipe. Can use the narrow steel billets to produce large diameter steel pipe is the most significant feature of the spiral pipe, widely used in all walks of life in China's gas pipeline construction. To reduce the coating quality, layer type and the construction of environmental factors on the life of straight seam welded pipe coating life, regular welding of straight pipe to rust. Common methods of descaling are four, namely, pickling, cleaning, spray derusting and tool rust. Pickling is one of the most commonly used methods of derusting, not only as a reprocessing process after sand blasting, but also the surface of the straight seam welded pipe rust, oxide, worn coating completely removed, although this cleaning method can make steel surface roughness and cleanliness are up to standard requirements, but after all, is a chemical cleaning method, the surrounding environment is likely to cause pollution. Straight seam steel pipe cleaning can only be used as an auxiliary means in the anti-corrosion treatment, because the cleaning method can only steel surface dust, grease, and lubricants and other residual organic matter removed, and can not play a preservative effect, as we usually wash their hands , You can clean the surface of the dirt, most of the bacteria still remain in the hand. Professional and technical personnel with steel wire brush and other cleaning tools to polish the surface of the workpiece, this approach is called tool rust, loose rust, welding slag and oxide, etc. can be completely removed, but the steel surface attached to the solid Scale is powerless, can not achieve the standard anti-corrosion effect. Spray derusting is the use of steel grit, steel balls and other high-quality abrasive material through the jet strong centrifugal force to the surface of straight seam steel pipe to spray, not only can effectively remove the surface dirt, rust and oxides, roughness will be abrasive And the longitudinal welded pipe friction under the standard level.

[1] Non-uniform cooling caused by residual stress. Residual stress is no external force in the internal self-phase equilibrium stress, a variety of cross-section of hot-rolled steel have such residual stress, the general section size of the larger steel, residual stress The residual stress is self-phase equilibrium, but it has certain influence on the performance of the steel member under external force, such as deformation, stability, anti-fatigue and so on. [2] After welding, the non-metallic inclusions in lsaw steel pipe are compressed into thin slices, which causes the delamination phenomenon, which greatly deteriorates the tensile properties of the straight seam steel pipe along the thickness direction, The local strain induced by weld shrinkage often reaches several times of the yield point strain, which is much greater than the strain caused by the load.