N.Y. Comp. Codes R. & Regs. Tit. 12 §§ 14-9.24

Current through Register Vol. 46, No. 45, November 2, 2024

Section 14-9.24 - Stop valves

(a)

(1) Each steam-discharge outlet, except safety-valve or safety relief valves, or reheater inlet or outlet connections, shall be fitted with a stop valve located at an accessible point in the steam delivery line and as near to the boiler nozzle as convenient and practicable. When such outlets are over two inch pipe size, the valve or valves used on the connection shall be of the outside-screw-and-yoke rising-stem type so as to indicate from a distance by the position of its stem whether it is closed or open and the wheel may be carried either on the yoke or attached to the stem. A plug cock type valve may be used provided the plug is held in place by a guard or gland, the valve is equipped to indicate from a distance whether it is closed or open, and the valve is equipped with a slow-opening mechanism.

(2) If a shutoff valve is used between the boiler and its superheater, the safety valve capacity on the boiler proper must comply with ASME requirements. In a separately fired superheater installation, a stop valve is not required at the inlet or the outlet of the superheater.

(b)

(1) All stop valves and the fittings between them and the boiler shall be equal at least to the requirements of the American National Standards given in the ASME Code except where heavier construction is specifically required.

(2) In all cases the valves and fittings shall be equal at least to the American National Standard for 100 psi.

(3) Valves and fittings made of any material permitted by ASME for pressure ratings of 100 pounds or more, and marked as required, may be used for saturated steam service up to the rated pressure, except that in no case shall they be used for temperatures exceeding those permitted by ASME.

(4) The nearest steam stop valve or valves to the boiler drum or superheater inlet shall have a pressure rating at least equal to the minimum set pressure of any safety valve on the boiler drum at the corresponding saturated steam temperature.

(5) The nearest stop valve or valves to the superheater outlet shall have a pressure rating at least equal to the minimum set pressure of any safety valve on the superheater and at the expected superheated steam temperature; or at least equal to 85 percent of the lowest set pressure of any safety valve on the boiler drum at the expected steam temperature of the superheater outlet, whichever is greater.

(c)

(1) When boilers are connected to a common steam main, the steam connection from each boiler having a manhole opening shall be fitted with two stop valves having an ample free-blow drain between them. The discharge of this drain shall be visible to the operator while manipulating the valve. The stop valves shall consist preferably of one automatic nonreturn valve (set next to the boiler) and a second valve of the outside-screw-and-yoke type; or, two valves of the outside-screw-and-yoke type shall be used.

(2) When a second steam stop valve or valves is required, it shall have a pressure rating at least equal to that required for the expected steam temperature and pressure at the valve, or the pressure rating shall be not less than 85 percent of the lowest set pressure of any safety valve on the boiler drum and for the expected temperature of the steam at the valve, whichever is greater.

(d) When a stop valve is so located that water can accumulate, ample drains shall be provided. All drain lines, including pipe, fittings, and valves, shall comply with the requirements for steam piping or water piping according to the service.

N.Y. Comp. Codes R. & Regs. Tit. 12 §§ 14-9.24