Straight seam steel pipe weld heat treatment is a new technique to eliminate residual stress. Preheated before welding the material to a heat treatment temperature after the welding process and welding pieces of heating was continued to maintain this temperature, the soldering is completed using heat insulation cotton to its slow cooling. This method can effectively reduce residual stress and improve the stress corrosion resistance of metals.
NDT weld inside the pipe in the water supply as part of large steel works, especially the thickness t=30mm steel tube is used as a pipe bridge, both to withstand the water pressure, but also the burden of weight and water from the pipe forming moment, so the welding quality requirements are particularly high. For pipe bridge of t=30mm thick with a large-diameter steel pipe, the longitudinal seam and girth welds belong to a class, require 100% of X-ray film examination and 100 % of the ultrasonic flaw detection; while the thickness t=24mm buried pipe, belongs to a class of longitudinal seam welding, for 20 % of the X-ray film examination and 50 % of the ultrasonic flaw inspection.
Heat treatment after welding can reduce the residual stress, and heat treatment temperature is higher, the better to eliminate the residual stress. Large diameter steel pipe weld heat treatment can effectively improve the large-diameter steel pipe stress corrosion resistance, heat treatment temperature is higher, increasing resistance to stress corrosion is more significant. Diffusion of metal carbide coating technology is the workpiece on special media, the diffusion layer is formed on the surface of several microns to several tens of micrometers of the metal carbide layer. Large diameter steel pipe anti-corrosion of buried pipes and tubes inside out corrosion, are used to hang galvanized wire, spraying compressive strength of not less than 30N/mm2 cement mortar lining.
No comments:
Post a Comment