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42 Cards in this Set
- Front
- Back
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Which has more heating surface, a water or fire tube boiler? |
Water tube. The heating surface is the side with fire on it, so the water tube uses the OD, while the fire tube uses ID |
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What is boiler water tested for? |
Dissolved Oxygen, scale forming solids, Alkalinity |
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What chemicals control dissolved Oxygen? |
Sodium sulphite and hydrazine |
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What chemicals are added to control scale forming solids? |
Sodium Phosphate and Chelants |
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What chemicals are added to control alkalinity? |
Sodium Hydroxide and Caustic soda |
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How do you perform a hydro test on a boiler? |
1. Open the steam drum vent valve and gag the safety valves. If the valves can't be gagged, they can be removed and replace with blind flanges or plugs 2.open the vents on interconnecting piping. Close the steam outlet valve 3. Isolate the Guage glasses, pressure switches, and other control components not included in the test 4. Fill the system with treated water. Water should be between 70-120degF. All air should be vented as the system is filled. Once water overflows the vent, Close it 5.apply pressure at less than 50psi a minute. Do not subject any component to more than 1.5x the designed pressure rating 6. When test pressure is reached, inspect system for leaks and hold at test pressure for long enough to satisfy the code requirement 7.release pressure slowly through small drain valve. Fully open the vents and drains when the pressure drops below 20psi 8. If temporary handhole or manway gaskets were used, they should be replaced with new service gaskets. Un isolate control devices abd Guage glass. Reinstall safety valves |
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Describe the wet layup of a boiler? |
1. Clean the fire, steam, and water sides 2. Close the steam and water side using new gaskets 3. Fill the boiler with warm treated water until it reaches the vent. 4. Add 100ppm sodium sulfite 5. Add 200ppm caustic soda 6. Close vent 7. Maintain Pressure slightly above atmospheric |
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Your CE tells you the inspector is coming in 2 days. How do you prepare the boiler for an internal inspection? |
1. Extinguish the fire and allow the boiler to cool slowly 2. When cool, open the blowdown and drain valves, venting the boiler to atmosphere 3. LOTO the steam outlet, blowdown, feed, and fuel valves 4. Inspect and document internal conditions, then sweep/blow soot from all external surfaces (tubes, shell plates, seams) 5. Remove manhole, handhole plates, and inspection plugs. 6. Wash out loose deposits of sludge or sediment after noting condition on opening in the engineer's log 7. DO NOT OPEN BLOWDOWN unless no one is inside the boiler and there is no pressure on the line |
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What do you do if you have a low water condition in the boiler? |
*There is a level- blowdown glass and column, verify level. Reduce operation. Start pump or close bypass to het more water into the boiler *There is NO LEVEL- Shut down immediately. If already feeding water to the boiler, continue, but don't start if not. Secure boiler, open and inspect for damage |
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What makes a safety valve pop? |
The Huddling Chamber, which gives steam a greater surface area to act on after the valve starts to lift |
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Name two types of safety valve? |
Spring loaded and pilot operated |
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Can you have an internal pipe connection on a safety valve? |
Safety valves must have a flanged or welded inlet connection. If the boiler is less than 15psi and the safety valve is less than 4inches, it may be attached by threaded connection if there is enough threads |
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When are you required to have 2 main steam stop valves? |
Boilers connected to a common steam main, or when a single boiler is connected to a header having another steam source shall have two stop valves |
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List 7 safety devices used with automatic combustion control? |
Flame failure detection system Low water interlocks Fan and airflow interlocks Low fire start interlocks High steam pressure/ temp interlocks Fuel pressure/ temp interlocks |
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Name and explain 3 methods of non destructive testing? |
Ultrasonic- Ultrasonic waves are sent through a material and the distortion of the waves indicates damage Magnetic particle- small colored magnetic particles suspended in oil are painted on the material to be tested. The material is then subjected to a strong magnetic field. Any lack of continuity creates a pole that attracts the particles Radiography - xrays or gamma rays Liquid dye penetrant- dye is sprayed on the metal and excess is removed. After it dries developer is sprayed on that brings out the dye that has penetrated any cracks and pin holes |
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What is found on the boiler stamp? |
Manufacturer Year Built MAWP Safety Valve Relieving Capacity |
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Where are the code stamps located on an HRT boiler? |
The front of the tube sheet |
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Where is the code stamps located on a Scotch Marine boiler? |
10 or 2 o'clock as you look at the front of the boiler, stamped on the drum sheet near the water column |
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What is the efficiency gained by heating boiler feed water? |
For every 10 degree increase in temp, there is 1% efficiency increase |
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What can cause bulging in a boiler tube? |
Scale buildup on the water side or roof buildup on the fire side reducing heat transfer. Also a damaged burner directing flame directly onto a heating surface |
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What is the result of material buildup on the water and fire sides of a boiler? |
Reduced heat transfer and potentially bulging tubes |
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Why do we superheat steam? |
Superheated steam has more enthalpy per lb, ans is more effective at transferring thermal energy into mechanical energy. Superheated steam increases thermal efficiency |
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What is a superheater? |
A nest of tubes used to increase the temperature of steam above that which corresponds to its pressure. |
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What are the 2 types of superheater and where are they located? |
Radiant- in the furnace right next to where it can be exposed to radiant heat Convection- located behind screenwall tubes in the flow of combustion gasses |
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What is caustic embitterment? What causes it? |
The deterioration of material due to concentration of highly alkaline substances leading to weakening and breakdown of boiler metal |
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What is heating surface? |
The surface with products of combustion on one side and water on the other. It is measured from the fire side |
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What is furnace heat release? |
The amount of heat in btu's released per cubic foot of furnace volume per hour |
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How do you check for tube tightness? |
Hydrostatic test |
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Can a stay bolt be welded? |
No, welding is not permitted on braces or stays |
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How do you know when to close the header valve? |
Shut the header valve as soon as boiler pressure drops below line pressure ans the check valve shuts |
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How do you know when to close the main steam stop valve? |
When the boiler os secured, steam flow stops, and the header valve swings shut |
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What is a blowdown tank used for? |
To prevent hot water or steam from entering the sewer. Can be used for intermediate bottom blows an continuous surface blows. |
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What is the max temp and pressure of water entering a sewer? |
150deg F at 5psi MAX |
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Name 5 benefits of water tube boilers? |
*Incresed efficiency with higher temps and pressures *Design flexibility and rapid circulation prevents thermal cycling/stress *Thinner tube material means faster heat transfer rates * Thin tubes are easier to work and repair * Can produce saturated or superheated steam |
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How would you plug a tube in a water tube boiler? |
A tapered plug would be hammered into the tube at both ends |
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What is grooving in a boiler? |
A from of deterioration of a boiler plate, caused by a combination of localized chorosion and stress concentration |
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How many tubes can be plugged before replacement is required? |
10% |
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What determines the size of an economizer? |
The dewpoint on the stack |
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What are the size requirements for blowdown lines ? |
1"min, 2.5"max |
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What are 2 ways to control superheater temp? |
Desuperheater - line that goes back through the steam drum to shed heat and reduce superheat Attemperator - desuperheater that functions by injecting feedwater into steam flow |
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How do you start a boiler on #9 FO, |
1. Recirc oil to get proper temp 2. Check lineup of pilot gas valves 3. line up atomizing steam=air lines and drain condensate 4. Establish drum level allowing for swell 5. Purge boiler 6. With oil at proper temp and press attempt light off 7. If burner doesn't light, isolate fuel, purge, and re attempt 8. Once burner ignites, adjust air dampers |
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What is the diameter of a Guage glass ? |
1-2.5" |
