Seamless Steel Pipe

Seamless steel pipes are steel pipes formed by piercing a single round steel bar, with no weld seams on their surface. Based on the production method, seamless steel pipes can be divided into hot-rolled seamless steel pipes, cold-rolled seamless steel pipes, cold-drawn seamless steel pipes, extruded seamless steel pipes, and jacking pipes. According to the cross-sectional shape, seamless steel pipes are divided into round and irregular shapes. Irregularly shaped pipes include square, oval, triangular, hexagonal, seed-shaped, star-shaped, and finned pipes, among other complex shapes. The largest diameter reaches 900mm, and the smallest diameter is 4mm. Depending on the application, there are thick-walled and thin-walled seamless steel pipes. Seamless steel pipes are mainly used as drilling pipes for oil and geological processes, cracking pipes for petrochemicals, boiler tubes, bearing tubes, and high-precision structural steel pipes for automobiles, tractors, and aviation.

Seamless steel pipes are generally made from high-quality carbon structural steels such as 10, 20, 30, 35, and 45, low-alloy structural steels such as 16Mn and 5MnV, or alloy structural steels such as 40Cr, 30CrMnSi, 45Mn2, and 40MnB, through hot rolling or cold rolling. Seamless pipes made from low-carbon steels such as 10 and 20 are mainly used for fluid transportation pipelines. Seamless pipes made from medium-carbon steels such as 45 and 40Cr are used to manufacture mechanical parts, such as load-bearing parts for automobiles and tractors. Seamless steel pipes generally require guarantees of strength and flattening tests. Hot-rolled steel pipes are delivered in hot-rolled or heat-treated condition; cold-rolled pipes are delivered in heat-treated condition.

Seamless Steel Pipe Production Process:

① Main Production Processes (Main Inspection Processes) of Hot-Rolled Seamless Steel Pipes:

Bill Preparation and Inspection → Billet Heating → Piercing → Rolling → Steel Pipe Reheating → Sizing (Reduction) → Heat Treatment → Finished Pipe Straightening → Finishing → Inspection (Non-destructive, Physical and Chemical, Bench Inspection) → Warehousing

② Main Production Processes of Cold-Rolled (Drawn) Seamless Steel Pipes:

Bill Preparation → Pickling and Lubrication → Cold Rolling (Drawing) → Heat Treatment → Straightening → Finishing → Inspection

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