Pressure explosions occur when a pressure part of the boiler such as the shell, furnace, or firetube bursts due to too high a steam pressure or a structural weakening of the metal. This weakening may be caused by:

Pressure explosions occur when a pressure part of the boiler such as the shell, furnace, or firetube bursts due to too high a steam pressure or a structural weakening of the metal. This weakening may be caused by:

1. corrosion
2. thermal stress
3. overheating
4. scale and sludge build-up
5. insufficient combustion air



a) 1, 3, 4, 5
b) 2, 3, 4, 5
c) 1, 2, 3, 4
d) 1, 2, 4, 5
e) 1, 2, 3, 5

Answer: A

Attempting to light a burner __________ may cause a furnace explosion.

Attempting to light a burner __________ may cause a furnace explosion.

a) from hot refractory
b) without preheating the fuel
c) without first cooling the fuel
d) without a pilot light
e) by pre-purging the furnace

Answer: A

Failure to __________ the furnace thoroughly before light-up can cause a furnace explosion.

Failure to __________ the furnace thoroughly before light-up can cause a furnace explosion.

a) heat
b) drain
c) prime
d) cool
e) purge

Answer: E

Poor combustion due to the insufficient amount of ______ may cause a furnace explosion.

Poor combustion due to the insufficient amount of ______ may cause a furnace explosion.

a) gas
b) fuel
c) heat
d) air
e) hydrocarbons

Answer: D

If the main burner fails, this could cause

If the main burner fails, this could cause

a) the steam atomizing pressure to increase
b) admission of unburned fuel to the furnace which may explode
c) the boiler efficiency to increase
d) the fuel valve to stay open
e) the pilot light to go out

Answer: B

Attempting to light one burner from another burner during the operation, can

Attempting to light one burner from another burner during the operation, can

a) cause the lit burner to be blown out
b) cause the fuel oil in the supply tank to surge
c) put the ignitor out
d) not cause the furnace to explode
e) cause a furnace explosion

Answer: E

One cause of flame failure in oil or gas fired boilers is

One cause of flame failure in oil or gas fired boilers is

a) excessive fuel temperature
b) fuel pressure being too high
c) the fuel being too volatile
d) water in the fuel
e) the hydrogen content is too low

Answer: D

The purging process for a furnace should be done

The purging process for a furnace should be done

a) before each burner is lit
b) with the fuel valve closed
c) with the fuel valve in the open position
d) before the second burner is lit
e) with the pilot light on

Answer: B

When additional gas burners are required, they may be ignited

When additional gas burners are required, they may be ignited

a) from an adjacent burner
b) by the flame detector
c) by means of a transformer relay
d) by a flame rod
e) by means of a torch

Answer: E

Most furnace explosions occur

Most furnace explosions occur

a) during the lighting up of a boiler burner
b) during the shutting down of a burner
c) during the purge period of lighting a boiler furnace
d) during the period of increasing the load
e) when steam pressure is excessive

Answer: A

The best method of ensuring adequate attention is being given to the boiler and its controlling and safety devices is to

The best method of ensuring adequate attention is being given to the boiler and its controlling and safety devices is to

a) schedule regular testing and checking procedures
b) maintain a log book showing testing results and by whom they were done
c) request staff to perform checks weekly
d) have faith in the personnel
e) always maintain good oral communication lines about tests and checks

Answer: B

A reason for many boiler accidents may be due to

A reason for many boiler accidents may be due to

a) inadequate training of operating personnel
b) log books being kept up to date and adequate
c) the regular testing and checking of control devices
d) not asking the insurance companies to inspect boilers more often
e) safety valves being oversized

Answer: A

A boiler pressure or waterside explosion

A boiler pressure or waterside explosion

a) could be the result of water in the fuel oil
b) could be the result of inadequate ignition
c) may be caused by a low water condition
d) could result from improper sootblowing procedures
e) could be the result of broken refractory

Answer: C

A firetube boiler furnace explosion

A firetube boiler furnace explosion

a) can be the result of too much scale on boiler tubes
b) is more disastrous than a pressure or waterside explosion
c) may be the result of oil in the water causing a foaming condition
d) may result from a flame scanner not working properly
e) could be caused by poor water circulation

Answer: D

What causes the level in the gauge glass to be lower than the water level in the boiler?

What causes the level in the gauge glass to be lower than the water level in the boiler?

a) steam valve on the gauge glass closed
b) shrinkage in the boiler steam drum
c) drain valve on the gauge glass leaking
d) top try cock open
e) the steam pressure is excessively high

Answer: C

What causes the level in the gage glass to be higher than in the drum?

What causes the level in the gage glass to be higher than in the drum?

a) column drain valve leaking
b) steam valve on the gage glass closed
c) swell in boiler steam drum
d) starting up of the stand-by feedwater pump
e) gauge glass steam and water valves are both open

Answer: B

If the boiler safety valves open during boiler operation, you should

If the boiler safety valves open during boiler operation, you should

a) close the non-return valve on the boiler drum
b) shut the boiler down immediately
c) increase the forced draft flow to cool the boiler
d) open the blowdown valves
e) reduce the fuel and air flow to the boiler

Answer: E

If the safety valve on a boiler pops and the only pressure gauge indicates well below pop pressure, you would

If the safety valve on a boiler pops and the only pressure gauge indicates well below pop pressure, you would

a) notify the Boiler Inspector
b) reduce boiler pressure and get the gauge checked
c) shut down to fix the safety valve
d) increase spring pressure on safety valve
e) shut down the boiler and replace the safety valve and gauge glass

Answer: B

When you first notice that the water level in the boiler gauge glass can no longer be seen, it is best first to

When you first notice that the water level in the boiler gauge glass can no longer be seen, it is best first to

a) ensure that the boiler is not over filled
b) start the stand-by feed pump or injector
c) shut off the boiler fuel supply
d) close the main steam valve
e) ensure the glass is not leaking

Answer: A

In the event of a flame failure, an automatic boiler will close the fuel valve and usually

In the event of a flame failure, an automatic boiler will close the fuel valve and usually

a) begin a re-start cycle immediately
b) perform a post-purge
c) reset itself
d) simply restart itself with no human intervention
e) stop the boiler feedpump

Answer: B