With the rapid development of high-quality strip rolling production and progress of welding and testingtechnology, and constantly improve the weld quality, varieties and specifications of welded steel pipe isincreasing, and instead of the seamless steel pipe in more and more fields. ERW production has the advantages of simple process, high production efficiency, low cost, rapid development. Spiral welded pipe ERW pipe strength than high, with a narrow billet production of large diameter pipe, can also use the same width of the billet production of different pipe diameters. But with the same length of straight pipe, weld length of 30~100%, and the production rate is low.
The first pipe molding process, uniform deformation of the steel plate, the residual stress is small, do notscratch the surface. The processing pipe has greater flexibility in diameter and wall thickness of the size range,especially in the production of high grade steel thick wall pipe, especially small and medium caliber thick wall pipe has incomparable technology advantage, can meet the requirements of users in more pipe specifications;the first pre welding after welding (both inside and outside finish welding process can be) in the best position of welding, welding is not easy to appear the wrong side, partial and incomplete welding defects, volume
If the overall mechanical expanding, can effectively improve the dimensional accuracy of welded pipe, and improve the internal stress distribution of welded pipe, so as to avoid stress corrosion damage, and is conducive to the construction site welding; quality inspection of 9 to 100% to make the whole process ofwelded pipe, welded pipe production are under effective detection, monitoring, and effectively ensure the product quality.
Welding process: raw materials - Flat - end uncoiling shearing and welding - Welding - - loop forming - both inside and outside the weld bead removal -- pre correction - induction heat treatment - sizing and alignment: eddy current testing - cut - - Pickling - water pressure check final inspection (strictly) - Packaging - shipment.
Welded pipe is widely used in water engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, urban construction, is one of China's twenty major product development.