according to DIN EN 10305-2
Steel grades: E235 • E355
supplied in the delivery conditions: +C and +N

or according to previous DIN standard:
DIN 2393
Steel grades: St 37 • St 52
supplied in the delivery conditions: BK and NBK

Range of dimensions:
Outer diameter: 4 to 150 mm
Wall thickness: 0.5 to 10 mm

* Grades and dimensions other than those listed here are
   available on request.