The Association of American Railroads' Manual of Standards and Recommended Practices, Section C-III, Specification for Tank Cars identifies two grades suitable for the construction of railcar tanks. TC 128, Grade B is a high-strength carbon manganese steel while the AAR ASTM A516, Grade 70 is a carbon steel produced in accordance with the supplementary requirements of AAR Specifications for Tank Cars for use in tank car heads, shells, and sumps. Each grade must meet the requirements identified in Appendix M-1002 of the AAR Tank Car Manual.
AAR A516 Grade 70
AAR TC-128 B