The LSAW steel production, spiral pipe production of hot-rolled coil. Hot strip rolling process unit has a series of advantages, metallurgical process for production of high quality pipeline capacity. For example, when the output of the gantry is equipped with a water cooling system to accelerate cooling, which allows the use of low-alloy components to achieve a particular strength level and low-temperature toughness, thereby improving the weldability of the steel. But this basic steel production plant. The coil alloy content (carbon equivalent) is often lower than similar grade steel, which also improves the weldability of the spiral pipe. More should be noted that, due to the spiral welded pipe coil rolling direction is not perpendicular to the pipe axis direction (sandwiched solution vary depending on the helix angle of the tube), while the straight seam steel plate rolling direction is perpendicular to the pipe axis direction, and therefore, the coil The crack pipe material is superior to straight seam steel pipe.
From the welding process, spiral tube, straight seam steel pipe welding method, but straight seam welded pipe inevitably there will be a lot of T-weld, so the probability of the presence of welding defects also greatly improved, and the T-shaped weld welding residual stress, the weld metal are often in a three-dimensional stress state, increasing the possibility of cracks. Moreover, according to the provisions of submerged arc welding process, each weld shall have the arc at the extinction at each straight seam welded pipe welding girth, unable to meet the conditions, which may be at the extinction Multiple welding defects.
Verified by the relevant comparative test, spiral pipe and Longitudinal yield pressure in good agreement with the measured and theoretical values âEUR
Pipeline development trend of large diameter, high strength. With the increase of the pipe diameter, steel grade increased, the greater the trend of steady expansion of ductile fracture tip. According to the test of the relevant research institutions in the United States, spiral pipe, longitudinally welded pipes with a level, but spiral welded pipe has a high impact toughness. Pipelines due to changes in transmission capacity, in actual operation, the tube is exposed to random alternating load. Understanding of the low cycle fatigue strength of the steel pipe has an important significance for Classifying the life of the pipeline. According to the measurement results of the fatigue strength of spiral welded pipe seamless and ERW pipe test data with seamless and resistance tube located in the same area, while higher than the average submerged arc Longitudinal.
Site weldability is primarily determined by the tube material and the port with the dimensional tolerances. Taking into account the requirements of the pipe installation and construction, steel processing continuity and consistency of shape geometry is particularly important. Spiral welded pipe production is basically stable continuous process under the same working conditions: Longitudinal production process is segmented, including the entire board / indenter / preroll / spot welding / welding / finishing / group multi-channel process process. This is an important feature of the spiral welded pipe production is different from welded pipe production. Stable production conditions is very easy to guarantee control of welding quality and geometry.
