I doubt you will find the maximum carbon equivalency (CE) for the fittings in the applicable specification. CE is not usually specified. However, the chemistry range is usually provided with the mechanical properties that have to be met. You could approximate the CE by using an appropriate CE formula and plugging in the average values based on the ranges for the chemistry listed in the specification. The maximum CE is still elusive unless the specification does happen to list a value (doubtful, but possible).

The other part of this problem is there are several CE formulas used by industry, each with its own guidelines. Unless your particular code or specification lists the CE formula that is required, you may obtain results that are meaningless.

Do you have CMTRs for the fitting you would like to use? If you do, you have the actual chemistry listed. You can use the CE formula listed in API Linepipe specification and hope for the best.

Best regards - Al