I agree with strider6. There has to be first a design basis document, Material Selection and Corrosion Control that describes the material selection criteria and corrosion control strategy like material selection, surface preparations and coatings, cathodic protection, chemical injection and corrosion monitoring systems. All this data shall be depicted in the MSD's in order the PID's to be issued accordingly.I think equipment data sheets and piping material classes specs are enough for a preliminary stage.In MSD you have to define the base material, corrosion allowance, internals/valves trim, internal coatings if any, service, design pressure and design temperature,required cathodic protection, chemical injection and corrosion monitoring points if any.GOOD LUCK!