2013-10-05 09:02:40 - Straight seam high frequency resistance welding pipe (Electric Resistance Welding, referred to as ERW) and seamless ERW biggest difference is that there are of welds, which is the key to the quality of ERW pipe.
Modern ERW pipe production technology and equipment, due to the international community, especially the United States and other years of unremitting efforts to make the seamless steel pipe ERW have been more satisfactory solution. Some of the ERW steel pipe, seamless seamless geometry and physics into seamless. Geometry is clear of ERW steel pipe seamless internal and external burrs. As the burr removal system within the structure and tools of continuous improvement and perfection, medium and large-diameter pipe within the burr removal has been a good deal. Within the burr can be controlled within-0.2mm ~ + O.5mm so. Refers to the physical seamless internal microstructure and weld the base metal caused by the difference between the mechanical properties of the
weld zone decreased the need to take measures to bring uniformity, harmonization. High-frequency ERW pipe welding thermal process, resulting in a gradient of temperature distribution near the edge of the tube, and the formation of a melting zone, semi-molten zone, heat tissue, normalizing area is not completely normalized area, tempering zones feature area. One hot zone of the welding temperature above 1000 the austenite grains grow rapidly in the cooling conditions will form a hard and brittle coarse crystalline phase, in addition to temperature gradient will produce welding stress. Thus, the formation of the weld zone mechanical properties than the base metal of the case, is through physical seamless weld heat treatment process that uses local conventional medium-frequency induction heating device to heat the weld area to AC3 (927 , then 60m length, speed of 20m / min of air-cooling process, water when the need arises. Use this method to eliminate stress, soften and refine the organization, improve the HAZ mechanical properties of the goal. Currently, the world's advanced ERW unit has been widely used this method to weld processing, has received good results. Quality ERW pipe weld not only can not be argued out, and the coefficient of a weld, weld regional organizations to achieve a match with the parent material.
ERW steel pipe for use with both hot-rolled coils as raw materials, wall thickness can be controlled within about ± 0.2mm, steel two-side by American standards or GB/T9711.1 standard APl, repair side playing groove, random length delivery and so on. In recent years, the natural gas pipeline projects and gas companies have been widely used in ERW steel pipe as the main distribution network.