Seamless steel pipe is a steel pipe made of a whole piece of metal with no seams on its surface. Seamless steel pipes are mainly used as drilling pipes in petroleum geology, cracking pipes in petrochemical industry, boiler tubes, bearing pipes and high-precision structural steel pipes for automobiles, tractors and aviation. (one-step molding)

Welded pipe, also known as welded steel pipe, is a steel pipe made of steel plate or strip steel after pressure welding, with a general length of 6 meters. (After secondary processing)

The essential difference between them is that the strength of welded pipe is generally lower than that of seamless pipe. In addition, welded pipes have many specifications and are cheap.

Production technology of straight welded pipe;

Raw material uncoiling-leveling-end shearing welding-looper-forming-welding-removing internal and external weld bead-pre-correction-induction heat treatment-sizing and straightening-eddy current testing-cutting-water pressure testing-pickling-final inspection (strictly controlled)-packaging-shipment.

Production technology of seamless steel pipe;

① Main production process (△ main inspection process) of hot rolled seamless steel pipe:

Tube blank preparation and inspection △→ tube blank heating → piercing → tube rolling → tube reheating → sizing (reducing) → heat treatment △→ straightening of finished tube → finishing → inspection △ (nondestructive, physical and chemical, bench inspection) → warehousing.

② Main production processes of cold-rolled (drawn) seamless steel pipes:

Blank preparation → pickling and lubrication → cold rolling (drawing) → heat treatment → straightening → finishing → inspection.

References:

Baidu encyclopedia seamless steel tube

References:

Baidu baike welded pipe