This isn't what you're looking for but...
B31.3 302.2.4 gives information on allowances for overpressure when determining your design pressure/temperature. It says "Subject to the owner's approval, it is permissible to exceed the pressure rating..." and goes on to set limits which by rule cannot be exceeded in any case. 302.2.4(f)(1)(a) says you can exceed the rating by no more than 33% for no more than 10 hours at any one time and no more than 100 hours per year.
Perhaps you can justify applying that limit. I can't say. It's important, though, to get the owner's approval.