Conn. Agencies Regs. § 29-232-62
Each steam boiler shall have a steam gage with the dial graduated to approximately double the pressure at which the safety valve is set but in no case to not less than one and one-half times this pressure, connected to the steam space or to the steam connection to the water column. The steam gage shall be connected to a siphon or equivalent device of sufficient capacity to keep the gage tube filled with water and so arranged that the gage cannot be shut off from the boiler except by a cock placed near the gage and provided with a tee or lever handle arranged to be parallel to the pipe in which it is located when the cock is open. An additional shut off valve or cock may be used near the boiler, provided the valve is locked open. The line shall be ample size with provision for free blowing. The connection to the boiler, except the siphon, shall not be less than one-quarter inch standard pipe size but where steel or wrought iron pipe or tubing is used, they shall not be less than one-half inch inside diameter. Each boiler shall be provided with a one-fourth of an inch nipple and globe valve connected to the steam space for the exclusive purpose of attaching a test gage when the boiler is in service so that the accuracy of the boiler steam gage may be ascertained.
Conn. Agencies Regs. § 29-232-62