Pipe Sehedule

Can we identify pipe schedule from its class?

No

Sorry unless you have the physical descriptions of those particular spec.s there is no way you'll be able to determine the schedule of the pipe. Those specs are written by a particular company, for a particular project. Another company "may" have another project similar to yours and spec maybe close too, but because they are by different authors the spec call-out names are probably totally different.

If you have a pipe spec prepared by the EPC (that was used to procure, fab, built and test) then the answer is YES. Part of the pipe spec family is the Piping Line Class Specifications. Here you will see the class designation, service, P-T limits, size range and the physical descritpion of the pipe, fittings and components.