It should be noted that ASME BPVC Sec I had changed the allowable stress for SA335P11 significantly, in 1968 edition. It was reduced for high temperature applications, and the allowable stresses at 1000 Deg F and 1050 Deg F were reduced 16% and 26%, respectively. Since no Part D of Sec II available at that time, I do not know the situations for other codes, such as Sec VIII and B31.1. However, in my personnel opinion, COADE should try to confirm if those remarkedly changes, if existed for B31.1, have been reflected by your CAESAR II, as you had introduced the pre-1968 code to it.