Excuse me, are you there? Stainless steel pipes are usually marked with material specifications and manufacturers on the outside of steel pipes? Equivalent to stamping.

There is no steel seal. Each pipe has laser printed data, implementation standards and specifications. The name of the manufacturer depends on your requirements. Be responsive. Not if you don't call the manufacturer, for example: 0Cr18Ni9GB/T14976-200257 * 3, which means: material 304, implementation standard.