Classification of galvanized seamless steel pipe processes

1. Medium thick plate unit: mainly produces wide and thick plates, used for the production of straight seam submerged arc welded pipes. The quality of straight seam submerged arc welded pipes is reliable and widely used in the main pipeline of oil and gas high-pressure transportation.
2. Steckel mill: The steckel mill includes a reciprocating roughing mill and a 4-roll reciprocating finishing mill. Two hot coil rolling 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, there is a significant change in the thermal mechanical history of the entire length of stainless steel stamped elbow fittings, especially in the production of micro stainless steel stamped elbow fittings. This will strongly affect the degree of recrystallization, grain growth, and precipitation generated on the finishing mill, and lead to significant changes in the final microstructure and properties of the entire length of stainless steel stamped elbow fittings
3. Semi continuous rolling mill: including 1 stand steckel mill and 5 stand finishing mill. On a semi continuous rolling mill, the hot rolling experienced by the pipe fittings in the finishing pass is essentially constant from one end of the pipe fittings to the other end. The time between passes on the finishing mill is usually less than 3 seconds.
4. CSP continuous casting and rolling: In the CSP production line, suitable controlled rolling, controlled cooling, and coiling processes are used for low-carbon manganese steel containing niobium, vanadium, and titanium composite microalloying, which can ensure that the mechanical properties and microstructure of the pipe fittings meet the technical requirements of modern X60 stainless steel stamping elbows and meet the development trend of modern stainless steel stamping elbow pipe fittings. China's CSP continuous casting and rolling production line has developed X60 stainless steel stamped elbow fittings, while other CSP production plants in the United States and abroad have developed and produced high-grade stainless steel stamped elbow fittings X60, X65, and even X70. The process characteristic is that there is center segregation in the continuous casting thin slab. Eliminating center segregation in the continuous casting thin slab for galvanized seamless steel pipes is a key technical issue to further improve the quality of stainless steel stamping elbow fittings. In the 1960s and 1970s, the plates used for stainless steel stamping elbows mainly used A3 and 16Mn produced by factories such as Ansteel. With the increase of pipeline diameter and transportation pressure, the strength of the pipe fitting plate cannot meet the demand. After the 1980s, various petroleum welding pipe parts factories began to use pipeline steel plates produced according to American API standards. Due to the immature technology of domestic stainless steel stamping elbow plate production plants at that time, imported plates were mainly used.