Many manufacturer applied more than one material specification and grades marking on products.
- ASTM A106 B / ASME SA106 B / API 5l PSL 1 B or ASTM A53 …
- ASTM A312 TP316/316L or TP304/304L
To undertsanding of multiple markings and acceptance criteria, The Committee has addressed variants of these questions in several interpretations: I-89-11, IIA-92-08, VIII-1-89-269, and VIII-1-89-197. and mandatory appendex III in ASME BPVC Section II B latest revision.