ASTM-A193 GR B7 ASTM-A193 GR B7 3lilaggies (Mechanical) (OP) 15 Jun 06 11:13 Looking for Pno and/or way to classify ASTM-A193 GR B7. It's not listed in ASME IX. Is there another source to find this information? RE: ASTM-A193 GR B7 metengr (Materials) 15 Jun 06 11:41 There is a reason for this - it is not permitted to be welded under ASME B&PV Code. If you must weld on Grade B7 you need to understand the heat from welding will adversely effect mechanical properties. You will not be able to assign a P-No, you can only list the chemical composition or Grade for welding.