ANSI NB 23-2 2002 pdf download INSPECTION TABLE OF CONTENTS
2.2.10.6 CONTROLS Establishing proper operation and maintenance of controls and safety devices is essential to safe boiler op- eration. Owners or users are responsible for establishing and implementing management programs which will ensure such action is taken. In addition, any repairs to controls and safety devices must only be made by qualified individuals or organizations. Documentation of compliance with these management systems and repairs is an essential element of demonstrating the effectiveness of such systems. When required by the Jurisdiction, the following guidelines are provided to aid in the evaluation of installed operating control devices:
a) Verify that the burner is labeled and listed by a recognized testing agency, that piping and wiring diagrams exist, that commissioning tests have been conducted and that a contractor/manufacturer’s installation report has been completed and is available for review.
b) Verify that the owner or user has established function tests, inspection requirements, maintenance and testing of all controls and safety devices in accordance with manufacturer s recommendations. Verify that these activities are conducted at assigned intervals in accordance with a writen procedure, that non-conformances which impact continued safe operation of the boiler are corrected, and that the results are properly documented. These activities shall be conducted at a frequency recommended by the manufacturer or the frequency required by the jurisdiction. Where no frequencies are recommended or prescribed, the activity should be conducted at least annually. Where allowed by the jurisdiction, Performance Evaluation may be used to increase or decrease the frequencies based on document review and approval by an appropriate engineer.
c) Verify that combustion air is supplied to the boiler room as required by the jurisdiction or if no jurisdictional requirements exist see NBIC, Part 1, 2.4.5 and 3.5.4 for additional guidance.
d) Verify that a manually operated remote boiler emergency stop button exists at each boiler room exit door, when required by the jurisdiction.
e) Verify operation of low water protection devices by observing the blowdown of these controls or the actual lowering of boiler water level under carefully controlled conditions with the burner operating. This test should shut off the heat source to the boiler. The retur to normal condition such as the restart of the burner, the silencing of an alarm, or stopping of a feed pump should be noted. A sluggish response could indicate an obstruction in the connections to the boiler.
f) The operation of a submerged low-water fuel cutoff mounted directly in a steam boiler shell should be tested by lowering the boiler water level carefully. This should be done only after being assured that the water level gage glass is indicating correctly.
g) On a high-temperature water boiler, it is often not possible to test the control by cutoff indication, but where the control is of the float type, externally mounted, the float chamber should be drained to check for the accumulation of sediment.
h) On forced circulation boilers, the flow sensing device shall be tested to verify that the burner will shut down the boiler on a loss of flow. i) On electric boilers, it should be verified that the boiler is protected from a low water condition either by construction or a low water cutoff or a low flow sensing device.