N.Y. Comp. Codes R. & Regs. Tit. 12 §§ 4-5.14
The minimum size of ferrous or nonferrous pipes connecting a water column to a steam boiler shall be one inch. The steam connection to the water column of a horizontal-return tubular boiler shall be taken from the top of the shell or the upper part of the head; the water connection shall be taken from a point not less than six inches below the center line of the shell. No outlet connections, except for damper regulator, feedwater regulator, steam gages or apparatus which does not permit the escape of any steam or water therefrom except for manually operated blowdowns, shall be attached to a water column or the piping connecting a water column to a boiler. If the water column, gage glass, low water fuel cutoff or other water level control device is connected to the boiler by pipe and fittings, no shut-off valves of any type shall be placed in such pipe; and a cross tee, or equivalent, in which a drain valve and piping may be attached, shall be placed in the water piping connection at every right angle turn to facilitate cleaning.
N.Y. Comp. Codes R. & Regs. Tit. 12 §§ 4-5.14