Note that the european 3.1B certificate used to be specified in accordance with DIN 50049. The EN 10204 standard is adopted from this standard. Just in case, this may ring a bell for a supplier.
Basically it means that the material certificate or mill report shall be issued by the manufacturers (own) independent inspection unit/department)
I would assume that any US supplier who has ever supplied piping components to Europe will be familiar with this type of certificate.
regards
Mogens