STEAM SYSTEMS CHAPTERS 3 & 4: Low Pressure Boilers & Steam Piping System
ASME Meaning
American Society of Mechanical Engineers
A ____ boiler is a boiler whose MAWP is not more than 15 PSI
LOW-PRESSURE STEAM HEATING
MAWP meaning
Maximum Allowable Working Pressure: The maximum pressure in PSI at which a boiler can be operated safely
NOWL Meaning
Normal Operating Water Level: The level of water maintained in the boiler to ensure safe and efficient operation
Bottom Blowdown Valves are located on the blowdown line and used to release water from the bottom of the boiler. (T/F)
TRUE
One pipe parallel flow steam systems should have a pitch of?
1" PER 20'
The drip leg on the end of the main drip should be atleast ____ " pipe and ____ " long
2" Pipe and 10" Long
The bottom of a steam header must be installed a minimum of ____' above NOWL of the boiler.
24" (2')
Steal pipe should be vertically supported at every other floor, not to exceed ____' between supports.
25'
In a Hartford Loop, the connection of the boiler return piping to the equalizing line typically should be made at 2" for residential boilers and ____" for commercial boilers below the boiler NOWL.
4"
The main air vent should be on a nipple ____ " tall and atleast ____" from the end of the main.
6-10" tall and 15" from main
What are the difference between a Safety Valve, Safety Relief Valve, and a Relief Valve?
A Safety Valve is used for gas or vapor service, A Safety Relief Valve is used for Steam, Air, Gas, Or liquids, and a Relief Valve is used for liquid service only. A Safety Relief Valve is essentially a combination of a Safety Valve and a Relief Valve. All are automatic and operate on the principle of preventing the boiler from exceeding its MAWP.
What do Gas Burners do inside boilers?
A gas burner is a heat-producing component of a gas combustion boiler. A burner mixes air and fuel to provide a combustable mixture.
What is an HRT boiler?
A horizontal return tubular boiler is a fire tube boiler suspended over a furnace.
What is an equalizing line?
An equalizing line is the vertical pipe that connects the boiler steam header to the boiler return pipe or return header. Sometimes called a balancing line, it equalizes the supply line and return line pressure preventing boiler water from flowing out of the boiler through the lower return main. Also allows condensation in supply header to drain to to the boiler return and reenter the boiler.
How often should boilers be inspected?
Annually or by whatever local ordinances state.
The ASME ____ standard covers high-pressure steam piping included in the design of chemical plants, petroleum plants, and refineries processing chemicals, hydrocarbons, water, and steam.
B31.3 - Process Piping
Why is Bottom Blowdown Performed?
Bottom Blowdown is performed for water level control, sludge and sediment removal, or dumping of a boiler
The advantages of ____ boilers are that they are available in a wide variety of sizes, can be packaged or field-erected, require very little maintenance, can be installed in tight spaces or older buildings with limited access, have a long service life, and a low initial cost
CAST IRON
A wet return line contains ____.
CONDENSATE WATER ONLY. Wet return line classifies any line mounted below the NOWL of the boiler.
CSA Meaning
Canadian Standards Association
The fitting attached to the safety valve that allows for the drainage of condensate is called?
DRIP PAN ELBOW.
This type of fitting should be used to reduce horizontal steam piping and installed using this orientation.
ECCENTRIC REDUCER. FOB
A(n) ____ balances the supply line and return line pressure, preventing boiler water from flowing out of the boiler through the lower return main.
EQUALIZING LINE
A(n) ____ is a U-shaped section of piping used to absorb expansion or contraction.
EXPANSION LOOP
What happens if outlet riser connection is greater or less than outlet port of the boiler?
Either can cause a change in steam flow velocity. A reduction in steam velocity may decrease steam flow in the system and a rise in steam velocity may cause an increased amount of boiler water to be carried into the steam supply piping. If steam leaving the boiler contains too much water, the latent heat contained in the steam will be absorbed into the water condensing it before it reaches and HTU's.
Difference between Blowdown Tank and Blowdown separator
Essentially the same in purpose however a Blowdown separator is more automated and doesn't vent steam to atmosphere. Additionally is always adding cold city water both condensing the flash steam and cooling the hot Blowdown water to then automatically discharge the tank when the water is at an acceptable temperature.
Its acceptable to reduce pipe size directly off the boiler to save money on install costs. (T/F)
FALSE
A safety or safety relief valve must be selected on basis of the size of the inlet piping connection. (T/F)
FALSE: A Safety relief valve must be selected on the basis of boiler capacity
A boiler operator can add water to a boiler with a low-water condition. (T/F)
FALSE: A boiler operator can add water to the boiler with a Feed water Regulator
All piping contracts when heated and expands when cooled. (T/F)
FALSE: All piping expands when heated and contracts when cooled
If there are two boiler outlets, the connection to the main riser should be made before the second boiler outlet connection. (T/F)
FALSE: For any amount of boiler outlets the connection to the main riser should be made after the last outlet connection
It's okay to cap one of the two outlets on a steam boilers. (T/F)
FALSE: IF both boiler outlets are not equally connected to the header the increased steam velocity from one outlet may cause the boiler NOWL to be slanted towards the connected Outlet.
The size of the boiler outlet riser connecting to the steam header should be larger in size than the outlet port of the boiler. (T/F)
FALSE: Should be equal to outlet
The equalizing line should reduce pipe size in the vertical part of the 90 elbow at the end of the main. (T/F)
FALSE: The equalizing line should reduce pipe size in the vertical part of the 90 elbow at the end of the HEADER.
Type K copper tubing is the type most commonly used in low-pressure steams systems. (T/F)
FALSE: Type L is the most commonly used
A(n) ____ system is a boiler system that supplies suitable water to the boiler at an appropriate temperature and pressure to maintain the steam cycle.
FEEDWATER
When steam main piping must be installed around an obstacle, a bypass assembly of piping using two tees and ____ 90 fittings should be used.
FOUR (In hydronics we piped under beam not over in steam you do both. Top for steam flow bottom for condensate flow)
What is Foaming?
Foaming is a boiler water condition caused by the formation of steam bubbles trapped below a film on the boiler water level surface that causes rapid fluctuation of water level as steam breaks through surface inconsistently.
Where is the Water Column/ Gauge meant to be placed in reference to water level?
For low pressure steam boilers the lowest visible part must be placed a minimum of 1" below the safe water level. For high pressure steam boilers the lowest visible part of the gauge glass must be placed a minimum of 2" above the lowest safe water level. As long as water is present in glass it is safe to add water to boiler
A(n) ____ creates an inverted seal providing positive protection against emptying of the boiler water due to the failure of return boiler piping.
HARTFORD LOOP
LWCO Meaning?
Low-Water Cut-Off: A device that is designed to monitor the water level in a boiler and to signal the boiler burner to shut down if the water level drops below the safe water level of the boiler.
A dry return line can not contain?
MONSTER ENERGY DRINK CANS. Classifies any line above the NOWL of the boiler can contain Condensate, steam or air at any given point.
NBBI Meaning
National Board of Boiler and Pressure Vessel Inspectors
All low-pressure steam boilers must have ____ or more water column/gauge glass boiler fittings to determine the water level in the boiler
ONE
In a ____ system, supply main horizontal piping is pitched upward away from the boiler main riser at a minimum grade of 1" per 10'
ONE-PIPE COUNTERFLOW
A ____ is a bent tube installed between the boiler and a boiler fitting that provides a water seal to prevent contact with steam.
PIPE SIPHON, These fill with condensate during operation which acts as the water seal prior to startup these are meant to be Primed (Filled with water).
A(n) ____ burner consists of a forced air fan that is used to bring air under pressure into close contact with the fuel
POWER
A ____ is normally a simple on/off control that regulates the amount of frequency of firing in a burner.
PRESSURE CONTROL. This is a switch that starts the burner, controls the firing rate, or shuts down the burner based on steam pressure. It is located at the highest part of the steam side of the boiler
Large and high-pressure boilers are required to have a ____ LWCO
PRIMARY AND SECONDARY
What is Priming?
Priming is a condition that occurs when small particles or large slugs of boiler water are carried into the steam lines
What is Safety Valve Capacity?
Safety Valve Capacity is the amount of steam in pounds per hour (lb/hr) the valve is capable of venting off. This capacity must equal or exceed a boilers pounds per hour rating.
Fuel Oil burner
Similar to how a gas burner mixes fuel and air to generate proper combustion in a gas boiler fuel oil burners atomize fuel oil with compressed air or steam to create proper combustion. Requires more intensive process because oil is thicker.
Downfeed branches and runouts can be taken from the ____ of the supply main
TOP OR BOTTOM. If taken off top should be done with vertical tee and 90 fitting to then drop down with another 90 fitting. if taken off bottom a tee should be rolled on a 45 to meet another 45 then connecting the drop with a 90.
What should not be done to a discharge line from a safety valve?
TRAP THE PIPE, DOWNSIZE THE PIPE TO SAVE MONEY, PLUG IT IF IT DRIPS, OTHER STUPID SHIT YOU KNOW YOU WOULDN'T DO.
A Hartford Loop is an arrangement of near boiler piping designed to protect boilers against the loss of water under conditions that otherwise would permit water to flow out of the boiler into the return main. (T/F)
TRUE
A steam pressure gauge should be graduated to at least 1 1/2 times the MAWP pressure of the safety valve or safety relief valve. (T/F)
TRUE
A three elbow swing is a method of protecting against expansion and contraction in a piping system using three elbows and connecting piping. (T/F)
TRUE
Fire-tube boilers were originally designed for use on ships and were called Scotch Marine Boilers. (T/F)
TRUE
If a feedwater regulator is in a combination LWCO and feeder, the feeder would actuate first to fill the boiler to the NOWL. (T/F)
TRUE
Most Cast iron boilers are limited to low pressure steam service (T/F)
TRUE
Most modern industrial boilers are water tube boilers (T/F)
TRUE
Piping and its supporting hanger should be one compatible system. (T/F)
TRUE
Slip type expansion joints can be used to absorb expansion and contraction, as well as eliminate noise and strain in baseboard radiator units. (T/F)
TRUE
The Safety Valve must be mounted in a vertical position. (T/F)
TRUE
Upfeed branches can only be taken off the top of the main (T/F)
TRUE. Preferably using a tee and fitting installed on 45 degree angle or accepted but not preferred using a tee and a fitting installed on a 90 degree angle.
Where is the Bottom Blowdown Line?
The Bottom Blowdown Line is located at the lowest point of the water side of a boiler. Lower pressure boilers may have one or two blowdown valves and any boiler operating at 100 PSI or more MUST have two
Where is the Surface Blowdown Line?
The surface blowdown line is piping located at the NOWL of the boiler and used to direct water to the blowdown tank.
What is a Water Column/ Gauge Glass
This is a boiler fitting mounted outside of boiler that reduces turbulence of boiler water to provide an accurate water level in a gauge glass. Has two connections that must be mounted to pressure side of boiler. bottom one must be mounted below NOWL and top in steam area above NOWL.
____ is the undesirable condition that occurs when steam comes in contact with condensate pockets.
WATER HAMMER
