Anyone know if there is a std. material in CII for Alloy 20 (Carpenter 20)?

Check B729. Otherwise, you may need to add the properties in the Material Database yourself. If you do this, do it twice. The first time input the expansion coefficient and elastic modulus as a function of temperature. Be sure to select ALL CODES as your piping code for this one and give it a material number of 600 or so. Then save it (Material->Save). Then select your piping code, add the allowable stress data and save it again with the same material number. Then you can access this from your input spreadsheet.