The key to the quality of thick-walled steel pipe thickness to the number of uniformity, thick-walled steel pipe wall thickness can not be directly affected by the quality control and use of thick-walled steel pipe, large diameter thick-walled steel pipe is generally used in a variety of mechanical processing, Wall parts processing, thick-walled pipe wall evenly will directly affect the quality of post-processing parts, thick-walled steel pipe wall is not controlled, the overall quality of the steel pipe is not strictly controlled. Choose the appropriate venue and warehouse storage of thick-walled steel pipe of the venue or warehouse, should be selected in a clean place, drain unobstructed, away from the production of harmful gases or dust factories and mines. In the field to clear the weeds and all debris, keep thick-walled steel pipe clean. In the warehouse shall not be with acid, alkali, salt, cement and other thick-walled steel pipe with corrosive materials stacked together. Different types of thick-walled steel pipe should be stacked separately to prevent confusion, to prevent contact corrosion. Large steel, rail, shame plate, large diameter thick-walled steel pipe, forgings, etc. can be open-air pile. Medium and small steel, wire rod, steel bar, thick-walled steel pipe in the caliber, wire and wire rope, can be stored in a well-ventilated shed, but must be on the next mat. Some small thick-walled steel, thin steel, steel, silicon steel, small diameter or thin-walled thick-walled steel pipe, all kinds of cold-rolled, cold-drawn thick-walled steel pipe and high prices, corrosion-resistant metal products can be stored storage. Treasury should be selected according to geographical conditions, generally use ordinary closed warehouse, that is, the roof has a wall, doors and windows tight, with ventilation of the Treasury. Treasury requires sunny attention to ventilation, rain, close attention to moisture, often maintain the appropriate storage environment. Reasonable stacking, advanced first put the principle of stacking requirements is stable in the palletizing, to ensure safe conditions, so that by species, specifications palletizing, different varieties of materials to be palletizing, to prevent confusion and mutual corrosion, prohibited in the Stacking near the storage of the corrosion of thick-walled steel pipe items, the principle of open-air piled steel, the following must have a wooden mat or stone, a little tilt stack to facilitate drainage, and pay attention to the material placed straight to prevent bending Deformation. Stacking height, artificial work of not more than 1.2m, mechanical operation of not more than 1.5m, stack width of not more than 2.5m. Between the stack and the stack should leave a certain channel, check the road is generally O. 5m, the access channel depending on the material size and transport machinery may be, generally 1.5 to 2. Om. Cushion bottom pad, if the warehouse for the sun's cement floor, pad height O. 1m can; if the mud, to be high O. 2 ~ 0.5m. If the open field, cement floor mat height 0.3 ~ O.5m, sand surface pad height 0.5 ~ O. 7m. Open piling angle and channel steel should be overlooking, that is, mouth down, I-beam should be put up, I thick-walled steel pipe surface can not face up, to prevent water from rusting.

Compared with the structure of other materials, steel structure has the following characteristics: First, the steel structure of light weight Although the bulk density of steel structure is large, its strength is much higher than other building materials, so when the load and conditions are the same, the steel structure is lighter than other structures, easy to transport and install, and can span more Large span.  Second, the plasticity of steel and good toughness Plastic, so that steel is generally not due to accidental overload or local overload and sudden rupture. Good toughness, then the steel structure of the adaptability of the dynamic load. These properties of steel to provide a safe and reliable steel structure to provide a full guarantee. Third, the steel is closer to homogeneous and isotropic The internal structure of steel is relatively uniform, very close to homogeneous and isotropic body, within a certain stress amplitude is almost completely elastic. These performance and mechanical calculations in line with the assumptions, so the steel structure of the calculation results more in line with the actual force situation.  Fourth, the steel structure is simple, easy to use industrial production, construction and installation cycle is short Steel structure from a variety of profiles, making simple. A large number of steel structures are manufactured in specialized metal structure manufacturing plants; high precision. Made of components transported to the scene assembled, bolted, and the structure of light, so the construction is convenient, the construction period is short. In addition, the completed steel structure is also easy to disassemble, reinforce or modify. Fifth, the steel structure of good sealing Steel structure of the air tightness and watertightness better. Sixth, the heat resistance of steel structure is good, but the fire performance is poor Steel heat and not high temperature. As the temperature increases, the strength decreases. When there is radiant heat around, the temperature above 150 degrees, it should take shelter measures. If the event of a fire, the structural temperature of 500 degrees or more, it may all instantaneous collapse. In order to improve the fire resistance of steel structure, usually with concrete or brick it wrapped up. In this case, Seven, Easy to rust steel, should take protective measures Steel in the humid environment, especially in corrosive media environment easily corroded, must paint or galvanized, and should be regularly maintained during use.

The quality of welded pipe depends on the quality of welding. The quality of welding is not only directly related to the quality of the tube, especially with the design of the forming roll, the forming process, the choice of welding parameters. These factors with the equipment to adjust the state and the rapidly changing, only by visual inspection of welding sparks, shavings and simple flaring state, flattening test and other empirical methods of control, it is difficult to maintain a stable quality. The shape and width of the weld affected zone are closely related to the welding speed, temperature, extrusion force and even tube thickness. When the welding speed constant, the heat affected zone width and welding temperature is proportional to (ie, the higher the temperature, the width of the larger), and inversely proportional to the extrusion force (ie, the greater the extrusion pressure, the smaller the width); when squeeze (Ie, the higher the temperature, the greater the width), and inversely proportional to the welding speed (that is, the faster the faster the width of the smaller); when the welding temperature does not change, the heat-affected zone width is proportional to the welding temperature, The width of the heat-affected zone is inversely proportional to the extrusion force (ie, the larger the squeezing force and the smaller the width), and is inversely proportional to the welding speed (ie, the faster the width and the smaller the width). Thus, the welding process should be welded within the scope of safety, fully explore the potential of pipe equipment, according to the wall thickness of the tube, the rational allocation of induction coil position and the size of the opening angle to ensure adequate heat output conditions, and gradually increase the welding Speed, the appropriate extrusion force to make the formation of the ideal heat affected zone shape, and in this state stable operation, the welding quality will be able to steadily improve.

High frequency straight seam welded steel pipe welding quality defects are cracks, welding, water leakage, scratches and so on. First, cracks Fracture is the main defect of welded pipe, its manifestation can be by the usual cracks, local periodic cracks, irregular intermittent cracks. Some of the steel pipe after welding surface without cracks, but by the flattening, straightening or hydrostatic test cracks. Severe leakage will leak. There are many causes of cracks. Elimination of cracks is one of the most difficult problems in welding adjustment operations. Second, take the welding Lap welding is the edge of the tube in the welding when the dislocation, although the curette can still see the traces of dislocation. 1) Molding quality is not good. Forming the edge of the tube is not usually appear on both sides of the usual lap welding, forming the edge of the wave and the drum package, the local small lap. 2) The production of thin-walled tube, the squeeze pressure properly, easily lead to drought. In the squeeze roll hole type center tube inside the installation of a small roller, can effectively overcome the thin-walled pipe lap welding. 3) Extrusion roller installation uneven, a high and one low, resulting in welding. 4) Strip edge slitting bad, curling or edge burr is too large, resulting in lap welding. 5) Forming vertical roller, horizontal roller and squeeze roll rolling center line is not a straight line, or a sickle with steel bends, resulting in unstable molding, weld reverse, resulting in lap welding. 6) When the position of the front end of the resistor is just at the center of the squeeze roll, the flaring strength value and the crushing strength value are the best. When the center line than the extrusion roller, stretching to the sizer side, the flaring strength and crush strength are significantly reduced. When less than the center line in the molding machine side, but also reduce the welding strength.

Cold pressure welding , at room temperature conditions, with the help of the metal to be welded to produce plastic deformation and solid-state welding method. Pressure deformation, the workpiece contact surface of the oxide film is destroyed and squeezed out, so that pure metal contacts to achieve intergranular bonding, to clean the welded joints. The applied pressure is generally higher than the yield strength of the material to produce 60 to 90% of the deformation. Pressing method can be slow extrusion, rolling or impact, can also be divided into several times to achieve the required amount of deformation. The main technical parameters of welding are determined by the mold size, so it is easy to operate and automation, the welding quality is stable, the productivity is high, the cost is low; Do not use flux, the joint will not cause corrosion. ; Welding joint temperature does not rise, the material crystalline state unchanged, especially for dissimilar metals and heat welding can not be achieved in a number of metal materials and products welding. Cold welding has become the electrical industry, aluminum products and space welding the most important in the field of one of several limited welding methods. Cold presses and the surface of the die may accumulate metal debris, must be regularly removed. If compressed air, compressed air can be used to blow off the debris. If you want to completely remove the debris, you can remove the mold from the welder, the mold of the four modules apart, with a magnifying glass carefully each module to ensure that all the surface of the module trace debris have been cleared. Mold removal must be careful, especially small springs easy to lose. The unclean surface of the mold will cause the wires to slip easily in the mold, so that the welding fails. Note that the mold after the maintenance of the work surface must not allow any grease.