Every steam boiler shall be equipped with a quick-opening blowoff valve. Steam boilers with an allowable working pressure in excess of 100 psi shall include a second valve; the valve closest to the boiler shall be quick-acting; the second valve shall be slow-acting. The valve(s) shall be installed in the opening provided on the boiler. The minimum size of the valve or valves shall be specified in accordance with Sections I and IV the ASME Code.