What is the definition of a boiler
A closed vessel in which water is heated under pressure to create steam
What is the definition of a pressure vessel
- A closed vessel in which the source of pressure is external to itself,
- not identified as a boiler
How often must boilers be inspected
Boilers operating over 15 psi shall be inspected internally and externally every year
How much notice is required to prepare a boiler for inspection
- 14 days for an internal inspection
- no notice is required for an external inspection
Which air tanks require an inspection
Tanks over 50 psi shall be inspected every 2 years
How does Chapter 146 determine boiler horsepower
- Rating on manufacturers tag
- Steam output on tag lbs/hr divided by 34.5
- BTU/hr input divided by 41,840
- BTU/hr output divided by 33,475
How does Chapter 146 determine engine horsepower
- P.L.A.N. divided by 33,000
- P=pressure constant (40, 50, 70)
- L= length of stroke
- A= area of high pressure piston
- N= number of strokes per minute
How does Chapter 146 determine turbine horsepower
- Horsepower is based on the outside diameter of the steam supply line
- less than 9 if OD is <1 3/4"
- 50hp if OD is >1 3/4 but < 3 1/2"
- 150hp if OD is > 3 1/2 but < 5.0
What can you do with a Second Class Fireman's license
Operate a boiler or boilers under the engineer or fireman in direct charge thereof
What information is on the certificate of Inspection
- Name of owner or user
- location, size and number of boiler
- date of inspection and signature of inspector
Where is the operator's license kept
In the engine or boiler room of the plant operated by the licensee
What boiler horsepower requires periodic attendance
9 to 250 HP
What boiler horsepower requires non-continuous attendance
251 to 500 hp
What boiler horsepower requires continuous attendance
Boilers with 501hp or more .
Who can appeal the results of a license exam
Any applicant aggrieved by the decision of a single examiner
List 4 methods used to classify boiler types
- fire tube / water tube
- direction of axis
- according to use
- location of furnace and operating pressure
What is a fire tube boiler
A fire tube boiler has products of combustion inside the tubes which are surrounded by water
What is a water tube boiler
A water tube boiler has water inside the tubes which are surrounded by the products of combustion
What is the difference between a dry-top vertical boiler and a wet-top vertical boiler
- A dry top vertical boiler has tubes which extend beyond the normal operating water level
- In a wet top vertical boiler the tubes are completely submerged by water
What does H.R.T. stand for
Horizontal Return Tubular
Why are HRT boilers sloped to the rear head
To allow for sludge or sediment to accumulate in this area where the bottom blow off pipe is located
Name 2 methods used to support HRT boilers
- lugs and rollers
- overhead suspension
Name 2 types of Scotch Marine boilers
Dry-back and wet-back
What is the primary difference between an HRT and a Scotch Marine boiler
An HRT is externally fired, a Scotch Marine is internally fired
Name 5 advantages of a fire tube package boiler
- Low cost
- Turnkey operation
- Limited space requirements
- No setting
- Automatic operation
How are water tube boilers classified
- Straight tube
- Bent tube
- Number of drums (miltiple, single, or none)
Why are water tube boilers used in electric generating plants
High capacity and almost unlimited pressure capability
Name 5 different types of water tube boilers
- Controlled circulation
- Forced circulation
- Natural circulation
How many pressure gauges are required on a boiler
At least one
How many safety valves are required on a boiler
- At least one,
- Boilers with more than 500 ft2 of heating surface require 2 or more safety valves
What is the purpose of a handhole
What is the purpose of a manhole
- A handhole allows limited access, not a person
- A manhole allows a person to enter into a boiler or pressure vessel
Name 3 special purpose boilers
- Hot water
What does HRSG stand for
Heat recovery steam generator
What is a longitudinal joint
What is a circumferential joint
- A longitudinal joint runs the entire length of the shell/drum.
- A circumferential joint (girth seam) is used to attach heads to form a closed cylinder.
What is a water column used for
To reduce the turbulence of the water in the boiler so an accurate level can be seen in the gauge glass
Describe a gate valve
- A gate valve is an isolation valve used either fully open or closed
- Not used for throttling applications
Describe a globe valve
A globe valve is an isolation valve used for throttling applications
What is the purpose of the main steam stop valve
Used to isolate the boiler from other boilers on a header for cleaning or repair
What is the purpose of the non-return valve
- Used to allow steam flow out of the boiler only
- flow in the opposite direction will close the valve and isolate the boiler
Explain how to cut-in a boiler equipped with a non-return valve
- Check water level and do walk around.
- Ignite fire in boiler, while boiler is warming open the bypass valve around the outside steam
- stop valve and with the free blow drain open warm the steam line from the header to the boiler.
- When the pressure is equal, open the outside steam stop valve and close the bypass.
- When boiler pressure is about 80% of working pressure open the stem on the non-return valve.
- When boiler pressure exceeds header pressure the non-return valve will open and the boiler will
- come on line. Close free blow drain.
When is more than one blowdown valve required?
Two or more blow down valves are required when the boiler is operating at 100 psi and above.
What is a slow opening valve?
What is a quick opening valve?
- A slow opening valve requires more than 5 full turns to be fully open
- A quick opening valve reuires less than 5 full turns to be fully open
Explain how you would blow down a boiler.
- Find true water level, 1/2 glass or better
- Open cooling water to blow down tank
- Open quick opening valve (inside valve)
- Open slow opening valve (outside valve) fully and close
- Close quick opening valve
- Check water level and close cooling water valve
Explain the principle operation of a bourdon tube pressure gauge.
- When pressure is applied into the curved hollow tube it tends to straighten
- The sealed end of the tube is connected to linkage and gears which turn a calibrated dial
- which indicates pressure
What is a siphon?
What is a snubber?
- A siphon is a device which prevents live steam from entering the bourdon tube
- A snubber is a device that reduces pressure fluctuations on the pressure gauge by gradually allowing pressure to enter the bourdon tube
What is the purpose of a water column?
To reduce the turbulence of the water in the boiler so that an accurate level can be seen in the gauge glass
How do you blow down a water column?
- By opening the drain valve fully, then closing it.
- Remember to disable the low water cut-out.
How do you blow down a gauge glass?
- By operating the top and bottom valves independently.
- Check for flow by opening drain.
Explain how you would test a low water cutout
By blowing down the water column or by performing a slow drain test on the boiler.
What is a closed feed water heater?
A shell and tube heat exchanger which does not allow steam and water to come in direct contact.
What is a check valve?
- A special purpose valve that allows flow in only one direction.
- Can't be locked opened or closed.
Where in the plant are you likely to find a check valve?
On the feed water line between the feed pump and the boiler.
What is a cyclone separator?
A device used on water tube boilers to separate moisture from the steam leaving the drum.
Where would a cyclone separator be located?
In the steam and water drum of a water tube boiler.
What is the purpose of a flash tank?
A flash tank or a blow down tank recovers heat from the blow down before discharging to the sewer.
Why would an inspector suspend or revoke your license?
For incompetence or untrustworthiness.
Name 2 types of vertical fire tube boilers.
- Dry top (exposed tube)
- Wet top ( submerged tube)
What is an economizer?
What does it do?
- An economizer is heat recovery equipment
- Designed to add heat to the incoming feed water by reducing flue gas temp.
What is an air preheater?
What does it do?
- An air pre-heater is heat recovery equipment.
- Designed to add heat to the incoming combustion air by reducing flue gas temp.
What is a bag on a boiler?
Where would it be located?
- A bag is a deformation or bulge in the shell plate
- Usually found on the bottom where sludge or sediment built up and caused over heating.
Explain the water circulation in a Sterling boiler.
- Feed waters enters the boiler at the rear drum
- Flows thru the down comers to the mud drum
- From the mud drum water travels upward thru the risers to the front drum
- From the front drum the path is to the center drum and back to the mud drum
Explain how you would respond to a low water condition.
- Find the true water level by blowing down the water column and gauge glass
- If the water level is low, secure the boiler (shutdown the fuel) and continue to feed water to the boiler
- Investigate the cause
Name 3 things a D.A. does.
- Removes oxygen and non-condensible gased from the water
- Heats the water and acts as storage capacity
- Convenient location to add chemicals
When is more than one Main Steam Stop Valve required?
- Two main steam stop valves are required on every boiler if more than one boiler is
- connected to a common header and the boiler has a manhole.
Explain how to find the "true water level"
- By blowing down water column and gauge glass
- Close drains and check level with tri-cocks
What is the Critical Pressure and Critical Temperature of steam?
What does a superheater do?
A superheater further increases the temperature of the steam after it has been removed from contact with the water.
What is a dry pipe?
A dry pipe is installed in the top of the drum to separate the moisture from the steam before the steam reaches the steam outlet.