North Dakota Administrative Code
Title 33.1 - Department of Environmental Quality
Article 33.1-14 - NORTH DAKOTA BOILER RULES
Chapter 33.1-14-05 - POWER BOILERS - EXISTING INSTALLATIONS
Section 33.1-14-05-14 - Feedwater valves and piping

1. Except for high temperature water boilers, the feed piping must be provided with a check valve near the boiler and a valve or cock between the check valve and the boiler. When two or more boilers are fed from a common source, there also must be a globe or regulating valve on the branch to each boiler located between the check valve and the source of supply. Whenever globe valves are used on feed piping, the inlet must be under the disk of the valve. On single boiler-turbine unit installations, the boiler feed shutoff valve may be located upstream from the boiler feed check valve.

2. 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.

3. If a boiler is equipped with duplicate feed arrangements, each such arrangement must be equipped as required by these rules.

4. A combination stop-and-check valve in which there is only one seat and disk and a valve stem is provided to close the valve when the stem is screwed down must be considered only as a stop valve, and a check valve must be installed as otherwise provided.

5. Where an economizer or other feedwater-heating device is connected directly to the boiler without intervening valves, the feed valves and check valves required must be placed on the inlet of the economizer or feedwater-heating device.

6. The recirculating return line for a high-temperature water boiler must be provided with the same stop valve, or valves, required by subsection 1 of section 33.1-14-05-13 for the main boiler and the required stop valve or valves is optional. A check valve may not be a substitute for a stop valve.

7. Except as provided for in subsections 8 and 10, boilers having more than five hundred square feet [46.45 square meters] of water-heating surface must have at least two means of feeding water. Each source of feeding must be capable of supplying water to the boiler at a pressure of six percent higher than the highest setting of any safety valve on the boiler. For boilers that are fired with solid fuel not in suspension, and for boilers whose setting or heat source can continue to supply sufficient heat to cause damage to the boiler if the feed supply is interrupted, one such means of feeding must not be subject to the same interruption as the first method.

8. Except as provided for in subsection 7, boilers fired by gaseous, liquid, or solid fuel in suspension may be equipped with a single means of feeding water provided means are furnished for the immediate shut off of heat input if the water feed is interrupted.

9. For boilers having a water-heating surface of not more than one hundred square feet [9.29 square meters], the feed piping and connection to the boiler may not be smaller than one-half inch [12.7 millimeter] pipe size. For boilers having a water-heating surface more than one hundred square feet [9.29 square meters], the feed piping and connection to the boiler may not be less than three-quarter inch [19.05 millimeter] pipe size.

10. High-temperature water boilers must be provided with means of adding water to the boiler or system while under pressure.

11. The feedwater must be introduced into a boiler in such a manner that the water will not be discharged directly against surfaces exposed to gases of high temperature or to direct radiation from the fire or close to any riveted joints of the furnace sheets or of the shell. For pressures of four hundred pounds [2757.92 kilopascals] or over, the feedwater inlet through the drum must be fitted with shields, sleeves, or other suitable means to reduce the effects of temperature differentials in the shell or head. If necessary, the discharge end of the feed piping must be fitted with a baffle to divert the flow from riveted joints. Feedwater may not be introduced through the blowoff.