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Marine engineering Class 3 > Oral steam questions > Flashcards

Oral steam questions Flashcards

1
Q

Describe a gauge glass and its safety features

A

Local boiler water level indicator.
Safety ball
Valves all point downwards in the run position.
Safety glass shield
Water level will be slightly lower than boiler level.

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2
Q

Blowdown a gauge glass

A

. Shut steam cock
. Shut water cock
. Open drain cock
. Slightly open the steam cock and wait for steam
through the drain. (steam line is clear)
. Slightly open the water cock and wait for water
through the drain. (water line is clear)
. Shut drain.
. Open water cock fully, (water should rise to the top of
the gauge glass)
. Open steam cock, (water should drop smartly down to
the correct level). (slowly will mean a restriction some
where in the water or steam lines)

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3
Q

When you open the water cock to put the glass back into service, the water goes to the top of the glass but when you open the steam cock, the water drains out of the glass. What do you do?

A

. Shut off the boiler flame
. Shut the inlet valve
. Shut the outlet valve
. Investigate by checking other gauge glass and or
Mowbray switch.
. if every thing is reading low, let the boiler cool down
and investigate the correct boiler water level.
. Investigate the low water level fault
. If water level was below the smoke tubes, seek expert
assistance/advice before using again.
.

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4
Q

How do you blowdown a boiler?

A

. Open overboard discharge or bilge valve
. Open the blowdown valve all the way the back ¼ turn
. Regulate the TDS discharge with the 3rd valve to
overboard discharge or bilge.

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5
Q

When would you use easing gear to open a safety valve?

A

. Test the boiler safety valve. (boiler depressurized)
. Quickly reduce steam pressure in a shipboard
emergency
. Quickly reduce steam pressure in a boiler emergency

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6
Q

. What inspections/checks do you do on a safety valve
when dismantled?
(Candidate said Examiner highlighted: drains are clear, valve and valve seat and checking spring length.)

A

. Drains are clean, clear and free flowing
. Valve seat and valve are in good condition
. Spring is not cracked and correct length

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7
Q

Purging – why, when and purging conditions?

A

(Conditions – fan on full speed, damper fully open and for the correct number of air changes.)
. To reduce the risk of an explosion
. Temporary flame loss, leaking fuel, unsuccessful
ignition
. Check for liquid fuel, Fan on 75% or more, register
open and correct number of air charges

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8
Q

Safety features of burner and register.

A 
. Low fuel oil pressure
. Lockout after power failure
. High high boiler pressure
. Low combustion air pressure
. Flame failure
. Low low boiler water level
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9
Q

What is the purpose of chemicals added to boiler water?

A 
. Reduce corrosion
. Reduce deposits and scale formation and convert into 
   sludge
. Reduce foaming
. Reduce carry over
. Reduce priming
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10
Q

What typical chemicals do you put in boiler water and what do the do?

A 
. Sodium phosphates
. Sodium hydroxide or sodium carbonate
. Polyelectrolytes, sodium aluminate, starch and tannins
. Sodium sulphite
. Antifoam agents
. Filming amines
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11
Q

Shut down and drain a boiler.

A

Follow OEM check list
(Don’t blow down all the way to avoid salt water getting back into the blowdown line – drain the remaining boiler water into the bilge.)

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12
Q

Sketch and describe a boiler.

A

a

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13
Q

Identify the safety features of combustion equipment (register/burner).

A 
. 2 fuel valves
. Flame sensor/detection
. Boiler purge cycle
. Burner Isolation 
. Low fuel pressure
. Low combustion air pressure
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14
Q

What are the causes of high chlorides?

A
  1. Pour water quality
  2. Incorrect water treatment
    3.
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15
Q

What things are you testing boiler water for?

A
  1. Oxygen levels (how much chemical treatment is left)
  2. PH level
  3. TDS, (salt left in the boiler water)
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16
Q

Why do you blowdown a boiler?

A
  1. To reduce the TDS left in the boiler

2. To shut the boiler down

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17
Q

You have mild oil contamination in your boiler water, what do you do?

A
  1. Scum the oil from the boiler surface
  2. Inveterate the oil source
  3. Repairs to oil source
  4. Water treatment, blow down the waste
  5. Document and report
  6. Seek expert advice
    7.
18
Q

What could have caused boiler oil contamination?

A
  1. Fuel oil heater leak
  2. Contaminated feed water
  3. Another source that the steam is heating
19
Q

Can you service a boiler safety valve?

A
  1. Yes if required in an emergency
  2. Should be inspected and test by certified repairers with a certificate every 12 months
  3. Class inspected if in class
  4. Document and record
20
Q

Causes of low boiler exhaust gas temperature.

A
  1. Incorrect fuel air mixture

2. Boiler water leak

21
Q

Problems with low boiler exhaust gas temperature

A
  1. Could be causing soot in the exhaust/furnace
  2. Could be fuel build up
  3. Boiler steam will not reach correct temperature
    4.
22
Q

What are the desirable properties of boiler water?

(pH, pAlk, TDS, and so on.)

A
  1. PH at the correct level (9-10)
  2. TDS
  3. Oxygen treatment is correct
23
Q

What impurities are there in boiler water?

A
  1. Oxygen
  2. TDS
  3. Acid or alkaline
24
Q

How do you deal with major oil contamination?

A
  1. Flame off
  2. Feed water off
  3. Steam off
  4. Investigat the contamination source
  5. Do not drain the boiler
  6. Seek expert help cleaning the boiler and condensate system
  7. Document and record
25
Q

Explain how/why a furnace explosion occurs.

A
  1. Fuel buildup in the furnace
  2. Incorrect purging
  3. Poor maintenance practices
26
Q

You have now shut down the boiler and opened it up. You have determined that the water level was below the uppermost smoke tubes. What actions would you take?

A
  1. Tag out the boiler as out of service
  2. Seek expert help
  3. Do not drain the boiler so the expert can see where the water level was
  4. Investergate the cause why the water level did not maintain the correct level
  5. Follow the expert advise
  6. Record and document
  7. Review and adjust procedures
27
Q

Firing a boiler from cold start - this was asked after crack repairs were carried out, the crack was in one tube end plate.

A

Follow manufactures and vessels start up procedures
. Switch on the pre heater (hotwell)
. Add chemicals to feed water, if not treated or test feed
water while filling the boiler to the low level alarm.
. Ensure vent are open to purge the system while filling.
. Slowly introduce heat to prevent condensation and
thermal stresses throughout the complete system.
. Use a thermal IR heat gun to test temperature.
. Monitor furnace water level, l\flame color/shape and
exhaust color.
. Keep system water temperatures, pressures and
treatment at correct levels.

28
Q

Boiler furnace purging, why, how and when?

A

To prevent the chance of unwanted combustion and potential explosions by purging/blowing/cleaning unburnt fuel from the furnace and exhaust spaces.
This also reduces heat and fuel (two sides of the fire triangle)
At lease 5 volumetric air changes of the boiler and exhaust ( or OEM set time)
Before and after every ignition attempt. after every flame shutdown.

29
Q

What is boiler water Total Alkalinity

A

Total alkalinity is the total concentration of bases and Total Dissolved Solids (TDS) in water expressed as parts per million (ppm) or milligrams per litre (mg/L) of calcium carbonate (CaCO3).

30
Q

What is boiler water Methyl Orange Alkalinity

A

Methyl orange alkalinity A measure of the total alkalinity in a water sample. The alkalinity is measured by the amount of standard sulfuric acid required to lower the pH of the water to a pH level of 4.5, as indicated by the change in color of methyl orange from orange to pink.

31
Q

What is boiler water Phenolphthalein Alkalinity ( P Alkalinity)

A

Phenolphthalein alkalinity is a subset of total alkalinity. Individual concentrations of hydroxide, carbonate and bicarbonate can be estimated by the phenolphthalein and total alkalinity measurements and use of the “Alkalinity Relationship Table” in alkalinity titration methods 8203 or 8221.

32
Q

What will a boiler flame look like if burning correctly

A

Bright orange or straw color flame, exhaust gas will be a light gray to brown haze.

33
Q

What will be the indication of to much air in a boiler flame

A

The flame will be bright white and the exhaust will be an opaque, white color.

34
Q

what will be the indication of insufficient air in a boiler flame

A

The flame will be dark orange with black smoke out the exhaust.

35
Q

Name the safety features of a boiler gauge glass

A

. One way safety ball after steam and water valves
. Threaded cleaning plugs to safely access/clear valves
. Protective shatter-proof/tempered gauge glass cover
. Backing outline for visual aid of level observation.
. Steam, water, and drain valves all face down in there
normal running position.

36
Q

Describe a boiler manhole door

A

. Sealed against the inside of the boiler (internal
pressure aids in sealing)
. Sealing clearance between manhole door and boiler
1.0mm +/- 0.5mm
. Elliptical in shape with radial edges for added strength

37
Q

Draw a boiler ordinary safety valve

A

a

38
Q

Explain the boiler easing gear

A

. Allows for safe system de-pressurisation in the event
of an emergency
. allows for the operation from a distance

39
Q

What is the surveyor looking for with a boiler safety valve

A

. Clear drains
. Valve a valve seat corrosion or cracking
. Spring length and tension
. Calibrated and tested with certification

40
Q

When should a boiler safety valve be tested, why do we need to gag a safety valve

A

. The boiler safety valve should be tested annually to
survey, OEM and class requirements
. Follow the vessels PMS procedures
. Gagging a boiler safety valve is necessary when
testing the 2nd safety valve
. Gagging can be done by manually locking/closing a
valve whilst the other valve is pressure tested.

Marine engineering Class 3 (17 decks)

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