Now with the factory working pressure established at 180 PSI, and with the understanding that I am completely unfamiliar with your engine, and operation, allow me to imagine the following possibility. At some previous inspection, someone spotted something that he didn’t like, be it pitting, or wasted stays, or what ever, and lowered the pressure to 150. Upon doing the thorough inspection and calculations required for the form 4, it was definitively discovered that what looked bad wasn’t nearly so bad from a strength standpoint, so the form 4 was completed with a forking pressure of 175 PSI which still allowed for a factor of safety of 4. Or you performed repairs on the weakened area to allow for the increase. Whether or not you raise the setting of your pop valve to that is you business.
The difference between this and the above situation is that your boiler is still certified at a pressure that is below the factory rating, not 11 percent HIGHER that the factory rating. I have seen many new form 4’s calculated, and I have yet to see one that allowed the boiler pressure to be increased above the factory setting. In the vast majority of cases, the pressure needs to be reduced, some times substatially, unless major repairs are undertaken.