Pressure Gauge on boiler

I had an annual boiler inspection done on my hot water boiler and the inspector (engaged by the boiler insurance co) said that my pressure gauge for the boiler needed to be replaced. He said that I currently have a 0 to 70 psi pressure gauge but I am required under NYC code to have a 0 to 100 psi gauge because it must be able to read two times the maximum allowable pressure of the boiler, which in my case is 50 psi. When I asked him where in the code/regulations this requirement appears, he could only say that it is based on his “schooling” and that he believes the requirement is in the NBIC (National Boiler Inspection Code) manual. I tried to look this up but couldn’t find the NBIC on line. Can anyone who has a copy of the NBIC or is knowledgeable of the code tell me if the inspector is right?