MEI:
I recommend getting your hands on a copy of the D14.1-97 specification. The welder qualifcations are similar, but important items like filler metal groups and specifications (including nonferrous metals), the inclusion of D15.1 for the rails (yes I know you are working on personnel lifts), classification of welds, loading, etc. differ substantially.

These codes are NOT equivelant unless the person who stamps the engineered drawings deems so.