Boiler Feeding

Boiler Feeding 1. Each boiler shall have a feed supply which will permit it to be fed at any time while under pressure. 2. A boiler having more than 500 square feet of water-heating surface shall have at least two means of feeding, one of which shall be an approved feed pump, injector or inspirator. A source of feed directly from water mains at a pressure six percent greater than the set pressure of the safety valve with the highest setting may be considered one of the means. As provided for in the ASME Power Boiler Code, Section I, 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 shutoff of heat input if the water feed is interrupted. 3. The feedwater shall be introduced into the boiler in such manner that it will not be discharged close to riveted joints of shell or furnace sheets, or directly against surfaces exposed to products of combustion, or to direct radiation from the fire. 4. The feed piping to the boiler shall 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 shall also be a valve on the branch to each boiler between the check valve and source of supply. Whenever a globe valve is used on feed piping, the inlet shall be under the disk of the valve. 5. In all cases where returns are fed back to the boiler by gravity, there shall be a check valve and stop valve in each return line, the stop valve to be placed between the boiler and the check valve, and both shall be located as close to the boiler as is practicable. It is recommended that no stop valves be placed in the supply and return pipe connections of a single boiler installation. 6. Where deaerating heaters are not employed, it is recommended that the temperature of the feedwater be not less than 120ø F to avoid the possibility of setting up localized stress. Where deaerating heaters are employed, it is recommended the minimum feedwater temperature be not less than 215ø F so that dissolved gases may be thoroughly released.