Watch what stress level you torque these bolts up to. The ambient yield stress on A193-B8 Class 1 bolts is only 30ksi and decreases with temperature. You can easily yield Class 1 bolts on the initial bolt-up and not know it. The joint will stay tight as the system heats up (bolt temperature lags behind process and flange temperature) but watch out as you reach steady state conditions or cool down -- potential leaks aplenty. Retorquing at temperature only compounds the problem.
Class 2 bolts have a higher ambient yield stress, on the order of 65ksi, but the standards don't require any differentiation on markings between Class 1 and Class 2 bolts. You need to add a supplemental marking requirement in your purchase order to be able to tell if you have Class 1 or 2.