N.Y. Comp. Codes R. & Regs. tit. 12, § 14-9.10 – Safety valve connections.

(a) When two or more safety valves are used on a boiler, they may be mounted either separately or as twin valves made by placing individual valves on Y bases, or duplex valves having two valves in the same body casing. Twin valves made by placing individual valves on Y bases, or duplex valves having two valves in the same body, shall be of approximately equal capacity. When not more than two valves of different sizes are mounted singly, the relieving capacity of the smaller valve shall be not less than 50 percent of that of the larger valve. When a boiler is fitted with two or more safety valves or safety relief valves on one connection, this connection to the boiler shall have a cross sectional area not less than the combined areas of inlet connections of all the safety valves with which it connects and shall also meet the requirements of section 14-9.10(b) of this Subpart.
(b) The safety valve or safety relief valve or valves shall be connected to the boiler independent of any other steam connection, and attached as close as possible to the boiler or normal steam flow path, without any unnecessary intervening pipe or fitting. Such intervening pipe or fitting shall be not longer than the face-to-face dimension of the corresponding tee fitting of the same diameter and pressure under the corresponding American National Standard. Every safety valve shall be connected so as to stand in an upright position, with spindle vertical. On high temperature water boilers of the watertube forced circulation type, the valve shall be located at the boiler outlet. Safety valves may be attached to drums or headers by welding provided the welding is done in accordance with Code requirements. Safety valves may be attached to drums or headers provided the welding is done in accordance with the requirements of this Part.
1. (1) The opening or connection between the boiler and the safety valve shall have at least the area of the valve inlet. No valve of any description shall be placed between the required safety valve or safety relief valve or valves and the boiler, nor on the discharge pipe between the safety valve or safety relief valve and the atmosphere. When a discharge pipe is used, the cross-sectional area shall be not less than the full area of the valve outlet or of the total of the areas of the valve outlets discharging thereinto and shall be as short and straight as possible and so arranged as to avoid undue stresses on the valve or valves.
2. (2) All safety valve or safety relief valve discharges shall be so located or piped as to be carried clear from running boards or platforms. Ample provision for gravity drain shall be made in the discharge pipe at or near each safety valve, and where water of condensation may collect. Each valve shall have an open gravity drain through the casing below the level of the valve seat. For iron and steel-bodied valves exceeding 2½inch size the drain hole shall be tapped not less than three-eighths inch pipe size.
3. (3) Discharge piping from safety relief valves on high temperature water boilers shall be provided with adequate provisions for water drainage as well as the steam venting. The installation of cast iron bodied safety relief valves for high temperature water boilers is prohibited.
4. (4) The discharge of safety valves or safety relief valves shall be located so as to prevent scalding.
(c)