Question 161Steam Plants - Assistant Engineer70% to pass
Why should the main steam stop valve of an auxiliary boiler be eased off its seat and then gently closed before lighting off?
AI Explanation
The correct answer is C) To ensure that the valve will not be seized shut when hot.
When an auxiliary boiler is lit off, the main steam stop valve is eased off its seat and then gently closed to ensure that the valve will not become seized shut when the boiler heats up. As the boiler warms up, the metal components will expand, and if the valve is left tightly closed, it may become stuck and unable to open when needed. Easing the valve off its seat and then closing it gently allows for this thermal expansion to occur without binding the valve.
The other answer choices are incorrect because they do not address the primary reason for this procedure, which is to prevent the valve from seizing due to thermal expansion. Examining the valve stem, checking the bonnet seal, or inspecting the valve packing are not the main reasons for this practice.
Related Questions
#159 When preparing to light off a cold boiler equipped with a return flow fuel oil system, the recirculating valve directs the flow of oil _______________.#160 Which of the automatic boiler controls listed should be tested prior to lighting off an auxiliary boiler? #162 Which statement is true concerning two-stage air ejector assemblies? #163 Main condensate recirculating systems are primarily intended to _______________.#164 Which of the devices listed is used to keep overheated condensate from flowing to the deaerating feed tank?