Piping classes usually group together pipe systems of similar pressure, material requirement, corrosion allowance etc, dependent upon the fluid. Commonly they are grouped by flange class, say (A = 150#), then material (C = CS), then corrosion allowance (3 = 3mm) then class would be AC3.
For piping class many companies use the PIP standard PNCM0002, Piping Material Specifications, Line Class Index issued by the Construction Industry Institute.
RA01 appears to be an in-house generated spec. Without a description what various term(s) in the spec mean it's impossible to guess. Companies can chose to indicate quite a range of details in the names for their piping specs or keep them very simply such as A spec.
