Seamless steel pipe is made from a single piece of metal, ensuring there are no seams or joints, thus enhancing its strength and corrosion resistance. Welded steel pipe, on the other hand, is made from welded metal sheets; while less expensive, it is slightly less strong than seamless steel pipe. Both types of pipe conform to ASTM A358 standards and are suitable for a wide range of industrial applications.

304，304L. 304H，321，321H，316，316L，316H，317L，317LMN，310S， 904L；S31803，S32205，S32750，S32760，S32304； Inconel 600，601，625， Incoloy 800， 800H， 800HT， Monel 400， Hastelloy C276； GH3030，GH3039，15CrMoG，16Mn., etc

Outer diameter generally ranges from 6mm to 630mm, wall thickness from 1mm to 60mm; length is mostly a standard 6-meter length, but custom lengths and double lengths are also available upon request.

Pressure resistance is related to the material, wall thickness, outer diameter, and temperature. Thicker walls and smaller outer diameters result in higher pressure resistance; however, allowable stress decreases at high temperatures.

Common surface treatments include industrial finish (pickled gray-white), pickled finish, and polished finish (internal and external polishing). Some may also undergo sandblasting, wire drawing, or passivation treatments.

In environments with strong acids, high salts, long-term water accumulation, or surface contaminants, rust or pitting may still occur; they are not absolutely rust-free.

Chinese National Standards: GB/T 14976 (Fluid Transport), GB/T 13296 (Boiler Heat Exchange);
American Standards: ASTM A312, A213, A269;
Petrochemical, nuclear power, and marine applications have their own specific standards.