There is no steel seal, but there are laser-printed materials, implementation standards and specifications, which are on each pipe. The name of the manufacturer depends on your request. If you ask, they will do it for you. If you don’t want it, the manufacturer will not. Will type, for example: 0Cr18Ni9 GB/T14976-2002 57*3, which means: material 304, implementation standard: national standard 14976 fluid pipe standard, specification 57*3, 57 represents the outer diameter, 3 represents the wall thickness.