Answer EKG Question 28
Q28. With respect to Exhaust gas fired auxiliary boilers;
A. Describe the procedure to be adopted for the inspection of a safety valve fitted to an exhaust gas boiler stating, with reasons, which parts should receive particularly close attention.
B. Describe the procedure for the setting of safety valves of exhaust gas fired auxiliary boilers;
A. Describe the procedure to be adopted for the inspection of a safety valve fitted to an exhaust gas boiler stating, with reasons, which parts should receive particularly close attention.
B. Describe the procedure for the setting of safety valves of exhaust gas fired auxiliary boilers;
C. Explain the action taken after the setting of safety valves as in (B).
Answer: A. The following part should be examined during overhauling or survey .
Valves or seat maybe marked or warn valve should ground in by means of a jig (since valve lid is wingless) taking care of makers specified clearance.
valve wings if fitted must be at least 0.8 mm clear in the seat and must not project below the seat.
The seat must be a good fit and securely held by set pins.
Inside of chest must be free from corrosion and any scale adhering removed.
Drain should be examined to see that it is clear.
The spring should be hammer tested to make sure that it is not fractured and inspected for corrosion.
The spring length should be tested against a new spare. The end of coil should be good fit in the recessed collar.
The valve spindle should be hammer tested ensure it is not cracked and check for alignment.
Clearance between the top of the cottor and top of the slot in the spindle to be checked after grinding a safety valve.
All bushes must be secured in the housing and have sufficient clearance.
Compression screw should be checked for tightness on the threads.
The easing gear must be checked to see that it is in good order.
After carrying out above inspection and adjustments the parts are assembled and valve made ready for setting to the required.
B. Describe how the safety valves are reset after an overhaul.
Pressure setting of safety valve:
Boiler safety valves are set to the required pressure using a standard tested certified pressure gauge as to its accuracy. A surveyor is present to see the test and issue certificate. Block one safety valve by gagging tool with little wrist tight. Ignite the burner and increase pressure with low flame until non block safety valve blow off. Shut the burner immediately adjust the blow off pressure and repeat until correct blow off pressure obtained. Adjust the second safety valve as described above setting tolerance of +/- 3% allowed by classification society.
C. Action taken after the setting of safety valves:
The compression ring is then machined and fitted in place and locked by Surveyor seal. Certificate is issued.
Valves or seat maybe marked or warn valve should ground in by means of a jig (since valve lid is wingless) taking care of makers specified clearance.
valve wings if fitted must be at least 0.8 mm clear in the seat and must not project below the seat.
The seat must be a good fit and securely held by set pins.
Inside of chest must be free from corrosion and any scale adhering removed.
Drain should be examined to see that it is clear.
The spring should be hammer tested to make sure that it is not fractured and inspected for corrosion.
The spring length should be tested against a new spare. The end of coil should be good fit in the recessed collar.
The valve spindle should be hammer tested ensure it is not cracked and check for alignment.
Clearance between the top of the cottor and top of the slot in the spindle to be checked after grinding a safety valve.
All bushes must be secured in the housing and have sufficient clearance.
Compression screw should be checked for tightness on the threads.
The easing gear must be checked to see that it is in good order.
After carrying out above inspection and adjustments the parts are assembled and valve made ready for setting to the required.
B. Describe how the safety valves are reset after an overhaul.
Pressure setting of safety valve:
Boiler safety valves are set to the required pressure using a standard tested certified pressure gauge as to its accuracy. A surveyor is present to see the test and issue certificate. Block one safety valve by gagging tool with little wrist tight. Ignite the burner and increase pressure with low flame until non block safety valve blow off. Shut the burner immediately adjust the blow off pressure and repeat until correct blow off pressure obtained. Adjust the second safety valve as described above setting tolerance of +/- 3% allowed by classification society.
C. Action taken after the setting of safety valves:
The compression ring is then machined and fitted in place and locked by Surveyor seal. Certificate is issued.
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