Question 135Steam Plants - 1st Asst/Chief70% to pass
The MAWP of a boiler is 900 psi and the normal drop across the superheater is 20 psi. If the superheater safety valve is set to lift at 825 psi, the minimum settings of the drum safety valves allowed by Coast Guard Regulations would be _______________.
AI Explanation
The correct answer is B) 850 psi.
According to Coast Guard regulations, the minimum setting of the drum safety valves must be at least 25 psi above the normal operating pressure of the boiler. Since the MAWP of the boiler is 900 psi and the normal drop across the superheater is 20 psi, the normal operating pressure of the boiler is 900 psi - 20 psi = 880 psi. Therefore, the minimum setting of the drum safety valves must be at least 880 psi + 25 psi = 905 psi. The closest valid option is 850 psi.
The other options are incorrect because A) 825 psi is below the minimum required setting, C) 875 psi is still below the minimum required setting, and D) 900 psi is the MAWP of the boiler, not the minimum setting of the drum safety valves.
Related Questions
#133 Coast Guard regulations require that the relieving capacity of boiler safety valves must be checked _______________.#134 If the maximum steam generating capacity of a boiler is increased Coast Guard Regulations #136 A boiler superheater safety valve is set to lift at 450 psi #137 Which of the listed procedures is the most important factor to take into consideration when making repairs to the refractory surrounding the burner openings? #138 To assure a long service life for boiler refractory materials after installation, the most effective method is to _______________.