Process Classification Of Galvanized Seamless Steel Pipes

The amount of galvanizing on galvanized seamless steel pipes is very small, only 10-50g/m², and its corrosion resistance is much worse than that of hot-dip galvanized pipes. Regular galvanized seamless steel pipe manufacturers are allowed to use cold-dip galvanized pipes as water and gas pipes. The galvanized layer of cold-dip galvanized steel pipes is an electroplating layer, and the zinc layer and the steel pipe matrix are independently layered. The zinc layer is thin, and the zinc layer is attached to the steel pipe matrix, and is easy to fall off. Therefore, its corrosion resistance is poor. In newly built houses, it is forbidden to use cold-dip galvanized steel pipes as water supply steel pipes.

After pickling, the galvanized seamless steel pipe is cleaned in an ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride. To ensure quality, most of them do not use electro galvanizing (cold plating). Only those small enterprises with small scale and outdated equipment adopt electro galvanizing, and of course, their prices are relatively lower.

Hot-dip galvanizing is to pickle the steel pipe first to remove the iron oxide on the surface of the steel pipe, and then send it into the hot-dip galvanizing tank. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion, and long service life.

Medium and thick plate unit: mainly produces wide and thick plates to produce straight seam submerged arc welded pipes. The straight seam submerged arc welded pipes have reliable quality and are widely used in the main oil and gas high-pressure transmission trunk line. Steckel mill: The steckel mill includes a reciprocating roughing mill and a 4-roller reciprocating finishing mill. Two hot coil mills are installed on the conveyor lines on both sides of the finishing mill. The output roller table usually includes a laminar cooling system and a coiling station. On the steckel mill, the thermomechanical history of stainless steel stamping elbow pipes changes significantly over the entire length.

Especially in the production of micro stainless steel stamping elbow pipe fittings, it will strongly affect the degree of recrystallization, grain growth, and precipitation produced on the finishing mill, and lead to drastic changes in the final microstructure and properties over the entire length of the stainless steel stamping elbow pipe fittings. Semi-continuous rolling mill: including 1-stand furnace coil mill and 5-stand finishing mill. On the semi-continuous mill, the hot rolling experienced by the pipe fittings in the finishing pass is essentially constant from one end of the pipe fitting to the other end. The time between passes on the finishing mill is usually less than 3s.