P11, P22, P9 and P91 Material

The Rt % (and for all NDT's) depends not only of grade of the material. Pressure, Temperature, Thickness, Type of fluid.........

Normally when alloys with PWHT requires, % or full RT, a good practice is RT before and after PWHT

The % of NDT, particularly X-Ray (radiography) is specified by the governing Code. It is intuitive that for High pressure steam systems, 100% is most typically required. But, check the Code, first. A good place to start is with you supplier. they may have a metallurgist that can render a the help you need. Also, check your contract documents for the Code required, and engineering requirements that may specify more stringent testing that may be required by the Code.