The main production processes for large diameter seamless steel tubes are hot rolled large diameter seamless steel tubes and hot expanded seamless steel tubes. The maximum size of hot expanded seamless steel pipe is 325mm-1220mm and the thickest is 200mm, which is used for low density but strong shrinkage of steel pipe. Scrap tube finishing process using oblique rolling method or drawing method to expand the diameter of the tube. In a shorter period of time, thickened steel pipe can produce non-standard, special type of seamless pipe with low cost and high production efficiency, which is the international development trend in the field of pipe rolling.
Weight Calculation
Weight calculation formula for large diameter seamless steel pipe.
[(OD - wall thickness)*wall thickness]*0.02466 = kg/m (weight per meter)
General specifications
General technical conditions for large diameter seamless steel pipe.
People are accustomed to call it large diameter seamless pipe with an outer diameter between (89mm-1200mm) because of its larger diameter.
According to the wall thickness (5mm-200mm) it can actually be divided into: large diameter thick wall seamless pipe and large diameter thin wall seamless pipe.

Production process
Round pipe billet → heating → perforation → three-roll slant rolling, continuous rolling or extrusion → stripping → sizing (or reducing) → cooling → straightening → hydrostatic test (or flaw detection) → marking → storage

Mechanical properties
Mechanical properties of large diameter steel pipe is an important indicator to ensure the final use of large diameter steel pipe performance (mechanical properties), which depends on the chemical composition of the steel pipe and heat treatment system. Therefore, according to different application requirements, the mechanical properties of large diameter spiral steel pipe are introduced specifically from tensile strength, yield point, elongation, etc.