N.Y. Comp. Codes R. & Regs. tit. 12, § 14-9.33 – Feedwater valves.

(a) The feedwater piping for all boilers, except for high temperature water boilers complying with the requirements of subdivision (h) of this section, and for forced flow steam generators with no fixed steam and water line complying with the requirements of subdivision (i) of this section, shall be provided with a check valve and a stop valve or cock between the check valve and the boiler. The stop valve or cock shall comply with the requirements of ASME.
(b) The relative locations of the check and stop (or cock) valves, as required in subdivision (a) of this section, may be reversed on a single boiler-turbine unit installation.
(c) If a boiler is equipped with a duplicate feed arrangement, each such arrangement shall be equipped as required by these rules.
(d) When the supply line to a boiler is divided into branch feed connections and all such connections are equipped with stop and check valves, the stop and check valves in the common source may be omitted.
(e) When two or more boilers are fed from a common source, there shall also be a globe or regulating valve in the branch to each boiler located between the check valve and the source of supply. A typical arrangement is shown in Figure P-44(a). Wherever globe style valves are used on feed piping, the inlet shall be under the disk of the valve.
(f) A combination stop and check valve in which there is only one seat and disk, and in which a valve stem is provided to close the valve, shall be considered only as a stop valve, and a check valve shall be installed as otherwise provided.
(g) Where an economizer or other feedwater heating device is connected directly to the boiler without intervening valves, the feed valves and check valves required shall be placed on the inlet of the economizer or feedwater heating device.
(h) The recirculating return line for a high temperature water boiler shall be provided with the same stop valve, or valves, required by subdivisions (a) and (c) of this section. The use of a check valve in the recirculating return line is optional. A check valve shall not be a substitute for a stop valve.
(i) The feedwater boiler external piping for a forced flow steam generator with no fixed steam and water line may terminate up to and including the stop valve(s) and omitting the check valve(s) provided that a check valve having a pressure rating no less than the boiler inlet design pressure is installed at the discharge of each boiler feed pump or elsewhere in the feedline between the feed pump and the stop valve(s).