188 Questions
What is the primary consideration when selecting materials for pipe manufacturing?
Operating conditions of the piping system
Which ASME code addresses Power Piping and Process Piping?
B31.1
What type of iron is used for screwed fittings?
Malleable iron
What is the primary advantage of using cast iron in piping systems?
High resistance to corrosion and abrasion
What type of material is commonly used for instrumentation and water services in power plants?
Brass or Copper
What is the main difference between seamless and welded steel pipes?
Seamless pipes are manufactured without joints, while welded pipes are manufactured with joints
What is the purpose of the nominal pipe size?
To provide an approximate indication of pipe diameter
What is the difference between NPS and DN?
NPS is in inches and DN is in millimeters
What does the number represent for NPS 14 (DN 350) and larger pipe?
Actual outside diameter of the pipe
What is the purpose of the Schedule Number in pipe manufacturing?
To specify the wall thickness of the pipe
What happens to the inside diameter of a pipe as the wall thickness increases?
It decreases
What is the formula to determine the inside diameter of a pipe?
d = D - 2t
What is the purpose of a union in piping?
To provide an easy method for dismantling piping
What is the advantage of screwed connections in piping?
Easy assembly and disassembly
What is the purpose of a nipple in piping?
To make close connections
How many general methods are used to join or connect lengths of pressure piping?
3
What is the primary purpose of grease fittings in piping systems?
To provide lubrication
What is the function of a corrugated expansion joint?
To absorb endwise movement of the pipe
What is the main consideration when designing piping supports?
To carry the weight of the pipe and its contents
Why are pipe hangers or supports typically placed at 3-metre intervals?
As a general rule of thumb for ordinary installations
What is the purpose of Tees and Crosses in piping systems?
For making branch line connections at 90°
Where are pipe hangers and supports typically placed in relation to valves and heavy piping components?
Close to valves and other heavy piping components
What is the purpose of a pipe anchor in a steam piping system?
To anchor the pipe to a fixed surface
What type of thread is cut with a tap?
Female thread
What is the purpose of a pipe reamer?
To remove the internal burr of the pipe
What is the advantage of flanged connections over welded connections?
They permit disassembly
What is the purpose of a gasket in flanged connections?
To prevent leakage at the connection
Which type of flange is used in piping systems constructed from stainless steel or other costly materials?
Van Stone flange
What is the purpose of a bushing in piping systems?
To connect a smaller pipe to a larger pipe
What is the purpose of a plug?
To close off open pipe ends
What is the purpose of a return bend?
To reverse the direction of a pipe run
What is the purpose of a reducer in piping systems?
To reduce pipe size
What is the primary function of ring joint gaskets in high-pressure systems?
To seal the connection between the flanges
What is the main advantage of using welded connections over screwed or flanged connections?
They eliminate the possibility of leakage
Why are backing or back up rings used in welding larger pipes?
To prevent weld metal from protruding inside the pipe
What is the primary purpose of expansion bends in piping systems?
To allow for expansion of the pipe due to heat
What type of expansion joint is illustrated in Figure 12?
Slip Expansion Joint
What is the purpose of the semi-plastic packing in the Slip Expansion Joint?
To prevent leakage between the slip pipe and the joint body
Why are ring joint gaskets generally used for high-pressure and special services?
Because they provide a more reliable seal
What is the main disadvantage of using welded connections for piping?
They require a skilled welder
What happens to the piping system when it is heated?
It expands in length
What is the purpose of the flange and gasket surfaces being clean and free from foreign particles during assembly?
To ensure a reliable seal between the flanges
Which type of material is commonly used for ash handling systems, sewage lines, and underground water lines?
Cast Iron
What is the primary consideration when selecting materials for piping system?
Operating conditions of the piping system
Which type of material is not suitable for pressurized service due to its brittleness?
Cast Iron
Which ASME code addresses Power Piping and Process Piping?
B31.1, B31.3, and others
Which type of steel is used for special applications?
Cast steel
What is the most common piping material used in power plants?
Steel
What is the primary purpose of supporting piping?
To carry the weight of the pipe, valves, fittings, and insulation
What is the primary consideration when designing piping supports for steam pipes?
To support the weight of the pipe and its components
What is the benefit of placing hangers and supports close to valves and other heavy piping components?
To distribute the weight of the valves and components more evenly
What is the purpose of a corrugated expansion joint in a piping system?
To absorb a certain amount of endwise movement of the pipe
What is the general rule-of-thumb for placing pipe hangers or supports in ordinary piping installations?
At 3-metre intervals
What is the primary purpose of anchoring a steam pipe to a fixed surface?
To allow the pipe to expand its entire length towards an expansion joint
What is the primary reason for using ring joint gaskets in high-pressure and special services?
To withstand high pressure and special services
What is the main advantage of welded connections over flanged connections?
They eliminate the possibility of leakage
What is the purpose of backing or back up rings in welding larger pipes?
To prevent weld metal from protruding inside the pipe
What is the primary method of providing for expansion in pipelines?
Using expansion bends and expansion joints
What happens to the piping system when it is heated?
It expands in length
What is the purpose of lubricating bolt threads when assembling a flanged joint?
To facilitate tightening
What is the primary consideration when using welded connections for piping?
The availability of skilled labor
What is the purpose of the cross over method when tightening bolts in a flanged joint?
To tighten opposite bolts gradually and evenly
What is the significance of the Nominal Pipe Size (NPS) number for pipes up to and including NPS 12?
It represents the nominal inside diameter of the pipe
What is the advantage of using expansion bends over expansion joints?
They are preferred for high-pressure work
Why does the inside diameter of a pipe decrease as the wall thickness increases?
Because the outside diameter of the pipe stays the same
What is the purpose of the semi-plastic packing in the Slip Expansion Joint?
To prevent leakage between the slip pipe and the joint body
What is the purpose of the Schedule Number in pipe manufacturing?
To indicate the wall thickness of the pipe
What is the difference between the Imperial System and the metric system used to designate nominal pipe size?
The Imperial System uses NPS numbers and the metric system uses DN numbers
What is the primary purpose of a return bend in piping systems?
To change the direction of a pipe run
What type of thread is cut with a die?
Male thread
What is the primary advantage of using screwed connections in piping systems?
They are easier to assemble and disassemble
What is the purpose of removing the internal burr from a pipe after cutting?
To prevent the formation of an obstruction
What is the significance of the DN number in the metric system used to designate nominal pipe size?
It indicates the nominal inside diameter of the pipe in millimeters
Why are flanged connections generally used for high-pressure pipes?
Because they can withstand higher pressures than screwed connections
What is the advantage of using flanged connections over screwed connections?
They are more convenient to assemble and disassemble
What is the formula used to determine the inside diameter of a pipe?
d = D - 2t
What is the purpose of a bushing in piping systems?
To connect a smaller pipe to a larger pipe or fitting
What type of gasket is used for joining cast iron and steel flanges?
Full-face gasket
What is the purpose of the wall thickness of a pipe?
To increase the strength of the pipe
What is the significance of the Outside Diameter (OD) column in Table 1?
It indicates the outside diameter of the pipe in millimeters
What is the purpose of tapping the smaller pipe eccentrically in a bushing connection?
To facilitate drainage of water
What is the purpose of a plug in piping systems?
To close off an open pipe end or fitting
What is the advantage of using Van Stone flanges in piping systems?
They are used for piping systems constructed from stainless steel or other costly materials
What is the purpose of grinding the flange faces in a flanged connection?
To ensure the flange faces are absolutely flat and smooth
What is the primary purpose of finishing cements in insulation applications?
To provide a finish to other insulation applications
What is the temperature limit of insulating cements?
1038°C
What is the primary component of magnesia insulation?
Magnesium carbonate
What is the purpose of the reflective metal sheets in reflective metal insulation?
To reflect heat and prevent loss due to radiation
What is the typical shape of pipe insulation?
Half-cylindrical
What is the temperature limit of magnesia pipe covering?
320°C
What is the primary characteristic of an efficient insulating material?
A large number of microscopic air pockets
What is the primary purpose of insulating pipes carrying substances at a lower temperature than the surrounding air?
To prevent corrosion and dripping
What is the temperature range of Calcium Silicate insulation?
38°C to 650°C
What is the characteristic of Mineral Fibre (Rock and Slag Wool) insulation?
Practically neutral pH
What is the primary advantage of Elastomeric insulation?
Cost efficiency for low-temperature applications
What is the primary characteristic of Foamed Plastic insulation?
Lightweight with excellent moisture resistance
What is the temperature limit of Refractory Fibre insulation?
Up to 1650°C
What is the primary characteristic of Perlite insulation?
Low shrinkage and high resistance to corrosion
What is the primary purpose of using insulation in piping systems?
To prevent corrosion and dripping
What is the characteristic of Glass Fibre insulation?
Non-combustible and water absorbent
What happens when the bimetal strip in a steam trap heats up?
It deflects downward
What is the purpose of the small hole in the centre of the piston valve in an impulse trap?
To allow pressure to build up
Why does the valve in a thermodynamic trap shut when steam enters the trap?
Because the steam expands and travels at high velocity
What is the purpose of a sediment separator in a steam trap installation?
To separate sediment and condensate
How is a trap typically installed in a piping system?
At the lowest point in the system
What is the purpose of a bypass line with a globe valve in a steam trap installation?
To allow hand throttling while the trap is out of service
How is the proper operation of a trap determined?
By opening the test valve and closing the outlet gate valve
What is a characteristic of a correctly functioning thermodynamic or inverted bucket trap?
It intermittently discharges condensate with some flash steam
What is the purpose of locking out and tagging out the trap for inspection?
To ensure the trap is out of operation
What should be done on a regular basis to ensure the proper operation of the trap?
The sediment separator should be blown clean
What is the primary purpose of a steam trap?
To separate steam and condensate
What is the difference in the operation of mechanical and thermostatic traps?
Mechanical traps use floats, while thermostatic traps use temperature differences
What is the advantage of ball float traps?
They work well with both light and heavy condensate loads
What is the purpose of the bellows in a ball float trap?
To discharge air and CO2
How does an inverted bucket trap operate?
The bucket rises when condensate is present, and sinks when steam is present
What is the primary purpose of thermostatic traps?
To remove condensate from radiators
What is the operating principle of a bimetal steam trap?
The bimetal strips deflect when heated
What is the disadvantage of ball float traps?
They are vulnerable to damage from water hammer
What is the purpose of the vent in a ball float trap?
To discharge air and CO2
What is the common characteristic of mechanical and thermostatic traps?
They are both used to separate steam and condensate
What is the term used to describe a series of loud, violent shocks produced within the piping of a steam system?
Water Hammer
What happens when a motor driven centrifugal pump suddenly stops due to a power interruption or other pump 'trip'?
The water in the pump discharge line will stop and reverse direction
What is a more dangerous form of water hammer?
Water hammer caused by the interaction of condensate and steam inside a pipe
What happens when steam is introduced into a cold pipe or when flow in a steam pipe is very slow and normal cooling occurs?
The steam will revert to water and form condensate
What is the purpose of traps fitted to main lines, branch lines, and separators for drainage purposes?
To drain condensate from the system
What is the purpose of piping insulation in a power plant?
To reduce heat loss to the surrounding air
What happens when a bubble of steam becomes enclosed by cooler condensate?
The steam bubble will implode
What can cause water hammer if steam is admitted too quickly to a pipe containing water or condensate?
The steam will rapidly condense, forming a vacuum
What can happen if steam is admitted to a pipe containing water or condensate without first removing the water or condensate?
Water hammer will occur
What is the result of the inrushing water from one side of the steam bubble meeting the inrushing water from the opposite side of the bubble?
A loud bang or shock wave
What is the purpose of steam separators in steam piping?
To remove moisture droplets and other suspended impurities from the steam
What is the result of not constantly draining condensate from steam lines?
Water hammer and possible rupture of pipes or fittings
What is the primary purpose of steam traps?
To discharge condensed water from steam lines and equipment
Why is it important to recover condensate?
For heating, hot water needs, or for return to boilers
Where should steam traps be installed?
Where condensate accumulates
What is the consequence of not draining condensate rapidly?
Water hammer and possible rupture of pipes or fittings
What is the primary function of reflective metal insulation?
To reflect heat and prevent loss due to radiation
What is the temperature limit of magnesia pipe covering?
320°C
What is the primary consequence of admitting moisture-carrying steam to turbines or engines?
Most undesirable operating condition
What is the purpose of half-cylindrical sections in pipe insulation?
To fit over the pipe and reduce heat loss
How do steam separators remove moisture droplets from steam?
By changing the direction of steam flow
What is the composition of magnesia material?
Mainly of magnesium carbonate
What is the primary characteristic of finishing cements or one-coat cements?
Used in the lower intermediate range and as a finish to other insulation applications
What is the primary purpose of steam traps in a steam piping system?
To discharge condensed water from steam lines without allowing steam to escape
Why is it necessary to constantly drain condensate from steam lines?
To prevent water hammer and pipe rupture
What is the primary advantage of insulating cements?
Moderate insulation values
What is the primary purpose of recovering condensate in a steam piping system?
For heating, hot water needs, or for return to boilers
What is the result of not draining condensate rapidly from steam lines?
Water hammer and possible pipe rupture
What is the primary function of the bellows in a mechanical trap?
To vent air and CO2 from the trap
What is the disadvantage of the ball float trap?
It is vulnerable to damage from water hammer
What is the primary principle of operation of thermostatic traps?
Differences in temperature between steam and condensate
What is the purpose of the float in a mechanical trap?
To open and close the trap outlet valve
What is the advantage of the inverted bucket trap?
It is not affected by changes in steam pressure
What is the purpose of the plunger in a thermostatic trap?
To seat securely onto the discharge port
What is the primary function of the corrugated bellows in a thermostatic trap?
To contain a volatile fluid that boils when heated by steam
What is the primary characteristic of a thermostatic trap?
It operates based on differences in temperature between steam and condensate
What is the primary advantage of the bimetal steam trap?
It operates based on differences in temperature between steam and condensate
What is the purpose of the air vent in a mechanical trap?
To allow air to escape from the trap
Which insulating material has a service temperature range of 38°C to 650°C?
Calcium Silicate
What is the primary characteristic of a material that is suitable for use as insulation?
High insulating value
What is the primary reason why pipes carrying substances at a lower temperature than the surrounding air should be insulated?
To prevent dripping and sweating
Which insulating material is made from an inert siliceous volcanic rock, combined with water, and has a cellular structure of minute air cells?
Expanded Silica
What is the purpose of adding binders to Perlite insulation?
To resist moisture penetration
Which insulating material has a temperature limit of 1650°C?
Refractory Fibre
What is the primary characteristic of a good insulating material?
Low thermal conductivity
Which insulating material is non-combustible and has good sound control qualities?
Mineral Fibre
What is the primary advantage of using Elastomeric insulation in low temperature applications?
No jacketing required
What happens when the bimetal strip heats up in a thermodynamic trap?
It deflects downward to fully close the valve, keeping steam from passing to the condensate line.
What is the primary reason why pipes carrying substances at a lower temperature than the surrounding air should be insulated to prevent corrosion?
To prevent corrosion due to the water or condensate in the pipe
What is the purpose of the control cylinder in an impulse trap?
To provide a pressure difference for the piston valve to operate.
Why does the valve in an impulse trap shut when steam enters the trap?
Because the steam expands and travels at high velocity under the piston disk.
What is the purpose of the sediment separator in a steam trap installation?
To prevent foreign matter from entering the trap.
How often should the trap be inspected and serviced?
Depending on the condition of the line, as needed.
What is the purpose of opening the test valve and closing the outlet gate valve when inspecting the trap?
To determine if the trap is functioning properly.
What is the characteristic of a correctly functioning thermodynamic or inverted bucket trap?
It discharges condensate intermittently with some flash steam.
What is the purpose of the unions in a steam trap installation?
To permit the trap to be removed for repair or replacement.
What happens when the condensate entering the trap is at its saturation temperature?
It flashes into steam, causing the valve to shut.
Why is it important to follow safe work procedures when opening the test valve?
To prevent exposure to high-temperature condensate and steam.
What is the primary cause of water hammer in a steam system?
Rapid condensation of steam inside a pipe
What is the effect of higher steam pressures on water hammer?
Increasing the pressure differential
What is the result of a steam bubble imploding in a pipe?
Generation of a shock wave
Why is it important to remove condensate from steam pipes?
To prevent water hammer
What is the purpose of bypass lines around traps in a steam system?
To ensure positive drainage
What is the effect of admitting steam too quickly to a pipe containing water or condensate?
Water hammer
What is the purpose of insulation in a power plant piping system?
To retain heat and prevent injury to personnel
What is the result of steam entering a pipe containing cold condensate?
Rapid condensation of steam
What is the primary cause of repeated banging in small piping systems?
Formation of multiple steam pockets
What is the consequence of not removing condensate from steam pipes?
Water hammer
Learn about the materials used to manufacture pipes and how to select the right one based on operating conditions. Explore the ASME Piping Codes and their guidelines for safe material selection.
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