3. Boiler Mountings Rajan Bhandari
Objectives Identify major mountings fitted on a boiler. Explain the significance of each of the mountings. Interpret the relevant class regulations Identify the various components of a gauge glass and safety valve. Describe the constructional features of various basic types of gauge glasses and safety valves. Explain the procedure for gauge glass blowing through. Explain the procedure for setting a safety valve’s set pressure and blowdown. Discuss the maintenance procedure for safety valve assembly.
overview Mountings are crucial without which the operation of boilers is unsafe. Proper maintenance and care of the mountings is important for the safety of both the boiler and the personnel and to maintain optimum operating condition of the boiler.
List of mountings Safety valves Water level indicators Water level controller Water level alarms & cut-out assembly Remote water level transmitter Main steam outlet valve Pressure gauge & Pressure switches Feed water valves Burner assembly Air vent Water sampling valve Manholes, mudholes & peepholes Bottom blowdown valve De-foaming (scum) valve Furnace drain valve Soot blowers
Mountings
Nameplate
Gauge glass Lowest visible water level Lowest permissible water level 25mm Lowest permissible water level Lowest visible water level 51mm Heating surface
Gauge glass
Gauge glass
Low water level cutout failure
Level switch and Alarms
Safety valves- Definitions Set Pressure: The boiler pressure at which the safety valve begins to lift. Closing Pressure: The boiler pressure at which the valve closes. Valve lift: The axial valve disc travel from closed to the open position. Blowdown: The difference between the opening and the closing pressures.
Safety valve set pressure
Full lift safety valve
Full Lift = L= D/4
Two step lifting action
Manhole door
Summary major mountings fitted on a boiler. significance of each of the mountings. Identify the various components of a gauge glass and safety valve. Describe the constructional features of various basic types of gauge glasses and safety valves. Explain the procedure for gauge glass blowing through. Explain the procedure for setting a safety valve’s set pressure and blowdown. Discuss the maintenance procedure for safety valve assembly.