288 Questions
What is a potential consequence of poor welding technique?
Introduction of gas pockets or solid impurities into the weld metal
What can occur when the heat from welding and flame cutting affects the weld metal?
It becomes brittle and susceptible to cracking
Why is it important to design a weld joint using sound engineering practice?
To ensure the weld is strong enough for the service conditions
What is the purpose of the ASME Code Section IX?
To provide guidelines for welding and brazing
What is the consequence of a defective weld joint?
It will not be strong enough for the service conditions
Why do provinces in Canada have laws stipulating that boilers, pressure vessels, and pressure piping be made in accordance with ASME Code Section IX?
To ensure the safety and integrity of these structures
What is the definition of welding according to ASME IX?
A localized coalescence of metals produced by heating or pressure with or without filler material.
What is the main difference between non-fusion and fusion welding?
Whether the parent metal is melted or not.
What is the role of flux in the non-fusion welding process?
To prevent oxidation of the metal surfaces while they are being heated.
What is the primary difference between brazing and soldering?
The temperature at which the process is performed.
Which of the following is NOT a characteristic of non-fusion welding?
The parent metal is melted.
What is the typical temperature range for soldering?
Below 450°C.
What is the primary advantage of using brazing for constructing copper heating boilers?
Copper is an excellent heat conductor.
What is the purpose of ensuring the parts fit properly before brazing or soldering?
To ensure the joint is clean and free of grease.
What is the difference between silver brazing and regular brazing?
The filler metal is stronger in silver brazing.
What is the primary purpose of heat in the non-fusion welding process?
To melt the filler metal and form an adhesive bond.
What is the approximate pressure of a fully charged oxygen cylinder?
2175 psi
What is the purpose of a pressure regulator in oxyacetylene welding and cutting?
To reduce the pressure of the gas to the required level
Why are oxygen and acetylene regulators not interchangeable?
Due to different thread types
What is the typical colour of the hose that supplies oxygen to the welding/brazing torch?
Green
What is the minimum temperature required to cut steel using oxyacetylene cutting?
870°C
What is the purpose of a flashback arrestor in oxyacetylene welding and cutting?
To prevent explosive flashbacks
What is the typical pressure of oxygen used to cut steel plate?
280 kPa
Why can't stainless steel be flame cut directly?
Because it rapidly forms heat-resistant oxides
What is the purpose of the cutting handle valve in oxyacetylene cutting?
To permit high-pressure oxygen to jet from the cutting tip
What is the approximate pressure of a fully charged acetylene cylinder?
1725 kPa
What is the primary difference between brazing and soldering?
Brazing uses a higher temperature than soldering
Which type of gas is used for brazing or very large soldered joints?
Acetylene
What is the purpose of flux in brazing and soldering?
To remove oxidation and promote the flow of filler metal
What is the primary characteristic of fusion welding?
The parent metal melts and mixes together
Which type of welding is no longer used for industrial purposes due to weak weld joints?
Forge welding
What is the term for the fuel used in OFW processes?
Any fuel that produces a high-temperature flame
What is the primary difference between OFW and brazing?
OFW heats the parent metal to above the melting temperature
What is the purpose of a hand torch in soldering?
To provide the correct amount of heat for the job
What is the term for the equipment used for brazing and soldering?
Non-fusion welding equipment
Why is MPS gas used for soldering copper pipe?
Because it produces a higher temperature than propane
What is the primary advantage of OFW over other welding processes?
Portability of equipment
What is the approximate temperature at which acetylene burns with pressurized oxygen?
3300°C
Why is acetylene dissolved in liquid acetone in the cylinder?
To reduce the risk of explosion
What is the purpose of the porous filler material in the acetylene cylinder?
To prevent the acetone from sloshing around
Why is oxygen a powerful oxidizer?
Because it promotes vigorous combustion
What is the recommended pressure for acetylene supply to a welding or cutting torch?
Below 100 kPa (15 psi)
What is the primary difference between an oxyacetylene outfit and an arc welding process?
Welding speed
What is the purpose of the needle valve in the oxy-fuel torch?
To control the flow of oxygen and acetylene
What is the importance of keeping valve protection caps in place and hand-tight when the cylinder is not in use?
To prevent physical damage to the cylinders
Why is OFW no longer commonly used in boiler, pressure vessel, and pressure piping manufacturing?
Due to its slower welding speed
What is the primary reason why a weld joint can be weakened despite being well-executed?
The weld joint is not designed using sound engineering practice
What is the consequence of introducing gas pockets or solid impurities into the weld metal?
The weld metal becomes brittle and susceptible to cracking
What is the purpose of the laws stipulated by provinces in Canada regarding boilers, pressure vessels, and pressure piping?
To ensure the safety and durability of boilers, pressure vessels, and pressure piping
What is the result of physically distorting a structure through improper weld methods?
The structure becomes useless
What is the primary reason why a weld joint that is defective will not be strong enough for the service conditions it will encounter?
The weld joint is not strong enough to withstand the service conditions
What is the consequence of the heat from welding and flame cutting affecting the weld metal?
The weld metal becomes brittle and susceptible to cracking
What is the primary purpose of the application of pressure in the welding process?
To ensure the coalescence of metals
What is the primary characteristic of the filler metal used in non-fusion welding?
It has a lower melting point than the parent metal
What is the primary difference between the base metal and the filler metal?
The base metal is the parent metal, while the filler metal is the added material
What is the primary purpose of cleaning the parts before brazing or soldering?
To remove oxidation from the metal surfaces
What is the primary advantage of using copper for constructing heating boilers?
It is an excellent heat conductor
What is the primary purpose of the silver brazing process?
To build-up the weld deposit thickness
What is the primary characteristic of the brazing process?
It involves melting the filler metal
What is the primary purpose of the ASME Code Section IX?
To provide guidelines for constructing boilers and pressure vessels
What is the primary difference between the soldering and brazing processes?
Soldering is done at a lower temperature than brazing
What is the primary purpose of the flux in the non-fusion welding process?
To prevent oxidation of the metal surfaces
What is the primary reason why OFW is not commonly used for boiler, pressure vessel, and pressure piping manufacturing?
All of the above
What is the purpose of the oxygen cylinder in an oxyacetylene outfit?
To supply pressurized oxygen to the torch
What is the approximate temperature at which acetylene burns with atmospheric oxygen?
2500°C
What is the primary purpose of the needle valve in the oxy-fuel torch?
To regulate the flow of oxygen and acetylene
What is the recommended maximum pressure for acetylene supply to a welding or cutting torch?
100 kPa
What is the primary advantage of OFW over other welding processes?
It is more portable and does not require an external power source
What is the primary purpose of the porous filler material in the acetylene cylinder?
To prevent the acetone from sloshing around
What is the approximate temperature required to melt steel using OFW?
3300°C
Why is oxygen a powerful oxidizer?
Because it is highly reactive
What is the primary purpose of the valve protection caps on the cylinders?
To prevent the cylinders from being damaged
What is the primary reason why MPS gas is used instead of propane for soldering copper pipe in sizes up to two-inch?
Because MPS gas burns at a higher temperature and has a greater heating value
What is the primary difference between OFW and brazing?
The temperature reached during the process
What is the primary advantage of fusion welding over non-fusion welding?
Fusion welding produces a stronger weld joint
What is the purpose of the mixing chamber in the torch used for soldering?
To mix air and propane
What is the primary characteristic of non-fusion welding?
The parent metal is heated below its melting temperature
What is the purpose of cleaning the remaining flux from the surfaces after brazing or soldering?
To prevent corrosion of the parent metal
What is the primary difference between oxyacetylene and MPS gas?
The heating value of the gas
What is the purpose of the orifice in the torch used for soldering?
To regulate the flow of propane to the burner tip
What is the primary advantage of using oxyacetylene outfits for brazing?
They produce a higher flame temperature
What is the primary difference between forge welding and fusion welding?
The method of joining the metal pieces
What is the primary reason for using a pressure regulator in oxyacetylene welding and cutting?
To reduce the pressure of the gas to the required level
Why is it essential to keep the threads of the oxygen cylinder and regulator clean?
To prevent combustion of lubricants or other materials
What is the typical pressure range of oxygen regulators used for cutting thick steel?
0-2760 kPa (0-400 psi)
Why is a flashback arrestor fitting necessary in oxyacetylene welding and cutting?
To prevent explosive flashback
What is the primary limitation of oxyacetylene cutting?
It can only be used for ferrous metals
What is the purpose of the cutting handle valve in oxyacetylene cutting?
To permit high-pressure oxygen to jet from the cutting tip
Why are oxygen and acetylene regulators not interchangeable?
Because of differences in thread types
What is the minimum temperature required to cut steel using oxyacetylene cutting?
870°C
Why can't stainless steel be flame cut directly?
Because it forms heat-resistant oxides
What is the purpose of the shut-off valve and threaded cap on a gas cylinder?
To prevent gas leakage when not in use
What is the purpose of having different threads on oxygen and acetylene cylinders and regulators?
To prevent accidental connection of the oxygen regulator to the acetylene cylinder
Why should lubricating and penetrating oil not be used on the oxygen regulator or pressure gauge threads?
Because they can cause combustible materials to ignite
What is the purpose of the special flame arrestor fitting in the gas supplies to the torch?
To prevent explosive flash back
What is the purpose of the shut off valve and threaded cap on each gas cylinder?
To protect the valve when a gas pressure regulator is not attached
What is the significance of the colours of the hoses that supply oxygen and acetylene to the welding/brazing torch?
The green hose supplies oxygen and the red hose supplies acetylene
Why is it important to keep the oxygen cylinder and regulator threads clean?
To prevent combustible materials from igniting
What is the primary reason why stainless steel and aluminum cannot be flame cut?
They rapidly form heat-resistant oxides when exposed to flame.
What is the purpose of the waster plate in flame cutting stainless steel?
To allow the cutting torch to be applied to the mild steel plate.
What is the primary difference between DCEN and DCEP in SMAW?
The amount of heat energy concentrated in the electrode.
What is the main advantage of using prime-mover driven welding generators?
They are portable
What is the purpose of the coating on the electrode in SMAW?
To provide a shield for the weld puddle
What is the function of the transformer in a SMAW power supply?
To change the voltage and current from one set of values to another.
What is the significance of the letter 'E' on an SMAW electrode?
It indicates the electrode is suitable for electric arc welding
What is the primary reason why DC machines are preferred over AC machines in SMAW?
DC machines provide better control of the welding process.
What is the typical pressure of oxygen used to cut steel plate?
280 kPa
What is the meaning of the first two digits of an AWS certified welding electrode?
The minimum tensile strength of the wire core material
What is the purpose of selecting an electrode with a tensile strength at least as great as the parent material?
To ensure the weld has the same strength as the parent material
What is the primary advantage of using DCEN in SMAW?
It produces higher rates of weld deposition and faster welding speeds.
What is the significance of the digit that follows the tensile strength in an AWS electrode designation?
It indicates the weld position the rod may be used in
What is the primary limitation of oxyacetylene cutting?
It is not suitable for cutting aluminum and stainless steel.
What is the purpose of the cutting handle valve in oxyacetylene cutting?
To permit high-pressure oxygen to jet from the cutting tip.
What is the purpose of the slag coating on the weld puddle in SMAW?
To act as insulation against the air while cooling takes place
What is the difference between a combustible and a mineral-coated electrode in SMAW?
The type of coating used on the electrode
What is the primary difference between the power supply for SMAW and oxyacetylene cutting?
The power supply for SMAW is electrical, while oxyacetylene cutting uses gas.
What is the purpose of the electrode coverings in SMAW?
To aid in stabilizing and directing the arc
What is the significance of the four-digit code on an AWS certified welding electrode?
It indicates the minimum tensile strength of the wire core material
What is the primary advantage of GMAW over SMAW?
It is faster and cleaner
What is the purpose of the rutile coating on the SMAW electrode?
To provide a gaseous shield and a slag coating
What type of welding process is GTAW?
Fully manual arc welding process
What is the primary characteristic of GMAW that makes it faster than SMAW?
The use of a continuous consumable wire electrode
What is the purpose of the inert shielding gas in GTAW?
To protect the weld area from atmospheric contamination
What is the primary advantage of GTAW over other welding processes?
It gives the operator greater control over the weld
What is the primary limitation of GMAW?
It is rarely used outdoors
What is the purpose of the power supply in SMAW?
To connect the work piece cable and the electrode holder
What is the primary difference between GMAW and SMAW?
The speed of the welding process
What is the primary characteristic of SMAW?
It uses a mineral coating of rutile and iron
What is the primary function of the flux in the Submerged Arc Welding process?
To shield the arc from the atmosphere
What is the purpose of the flux in the weld joint after the welding process is complete?
To protect the weld from oxidation
What is the typical maximum current used in Submerged Arc Welding?
4000 amps
What is the primary purpose of Post-Weld Heat Treatment (PWHT)?
To relieve stresses in the weld metal
What is the term used to describe the process of making steel harder by heating and then quenching (rapidly cooling) it?
Heat treatment
What is the primary advantage of using Submerged Arc Welding (SAW) over manual or semi-automatic welding?
Neater and more uniform appearance
What is the function of the machine in Submerged Arc Welding (SAW)?
To control the rate of weld progression and filler material admission
What is the primary difference between the constant voltage and drooping voltage characteristics of Submerged Arc Welding machines?
The self-adjusting arc length
What is the purpose of the granular flux in Submerged Arc Welding (SAW)?
To shield the arc from the atmosphere
What is the primary advantage of using two electrodes simultaneously in Submerged Arc Welding (SAW)?
Increased flexibility
What is the primary reason why a hardened cutting tool becomes brittle?
Because it is quenched in water or oil
What is the Heat Affected Zone (HAZ) in a weld joint?
The area where the weld metal and adjacent parent metal are heated
What is the purpose of post weld heat treatment (PWHT) in welded boilers and pressure vessels?
To restore the ductility of the weld metal
What happens when a brittle material is subjected to stress?
It breaks without deforming
What is the purpose of preheating a weld joint?
To prevent rapid cooling of the HAZ
Why do blacksmiths reheat a hardened cutting tool to a lower temperature?
To restore its ductility
What is the result of quenching a heated steel?
It becomes harder and more brittle
What is the purpose of the ASME codes in relation to boilers and pressure vessels?
To provide regulations for the construction and maintenance of boilers and pressure vessels
What is the difference between a brittle and a ductile material?
A brittle material breaks without deforming, while a ductile material deforms before breaking
Why is it important to use post weld heat treatment (PWHT) in boilers and pressure vessels?
To prevent brittle fracture
What is the reason for having different threads on oxygen and acetylene cylinders and regulators?
To prevent accidental connection of oxygen to acetylene cylinder
Why is it crucial to keep the oxygen cylinder and regulator threads clean?
To prevent combustible materials from igniting
What is the purpose of the green and red hoses in an oxyacetylene setup?
To supply acetylene and oxygen to the torch
What is the function of a flashback arrestor fitting in an oxyacetylene setup?
To prevent explosive flashbacks
What is the purpose of the shut-off valve and threaded cap on a gas cylinder?
To protect the valve when a regulator is not attached
Why is it important to use the correct thread on an oxygen cylinder and regulator?
To prevent accidental connection of oxygen to acetylene cylinder
What is the primary purpose of the slag coating on the weld puddle in SMAW?
To protect the weld metal from atmospheric contamination
What is the primary characteristic of GMAW that makes it faster than SMAW?
The lack of need for a welder to intermittently stop and replace filler rods
What is the primary advantage of GTAW over other welding processes?
Its ability to provide greater control over the weld
What is the primary purpose of the electrode coating in SMAW?
To provide a gaseous shield
What is the primary characteristic of the weld produced by GMAW?
It is cleaner and faster than SMAW
What is the primary purpose of the shielding gas in GMAW?
To protect the weld metal from atmospheric contamination
What is the primary difference between GMAW and GTAW?
The type of electrode used
What is the primary purpose of the power supply in GMAW?
To provide a constant voltage, direct current
What is the primary characteristic of the GTAW process?
It is a fully manual arc welding process
What is the primary advantage of SMAW over other welding processes?
It is a more forgiving welding process for beginners
What is the primary reason why stainless steel cannot be flame cut directly?
It forms heat resistant oxides when exposed to flame
What is the function of the cutting handle valve in a cutting torch?
To control the flow of oxygen to the cutting tip
What is the primary advantage of prime-mover driven welding generators?
They are portable
What is the result of the electrical energy converted into heat when an electric current passes from the weld electrode to the parent material in the form of an arc?
The generation of heat energy
What is the primary difference between DCEN and DCEP in SMAW?
The amount of heat energy concentrated in the electrode
What is the purpose of the gaseous envelope produced by the combustible electrode coating in SMAW?
To protect the weld puddle from oxygen, hydrogen, and moisture
What is the purpose of the waster plate in cutting stainless steel?
To allow the cutting torch to cut the stainless steel
What is the significance of the letter 'E' on an SMAW electrode?
It indicates the electrode is suitable for electric arc welding
What is the primary reason why cast iron is more difficult to cut than mild steel?
It is more brittle
What is the purpose of the slag coating on the weld puddle in SMAW?
To act as insulation against the air while cooling takes place
What is the primary function of the transformer in a SMAW power supply?
To change voltage and current values
What is indicated by the first two digits of an AWS certified welding electrode?
The minimum tensile strength of the wire core material
What is the primary advantage of using DC machines in SMAW?
They provide better control of the welding process
What is the primary difference between mineral-coated and combustible-coated electrodes?
The way they protect the weld puddle
What is the typical application of welding generators mounted on a truck or trailer?
Remote pipeline use
What is the primary purpose of changing the oxygen pressure in oxyacetylene cutting?
To suit the thickness of the plate being cut
What is the primary reason why oxyacetylene cutting is often referred to as ‘flame cutting’?
Because it is inaccurate
What is the purpose of the electrode coating in SMAW?
To protect the weld puddle and stabilize the arc
What is the significance of the digit that follows the tensile strength in an AWS certified welding electrode?
It indicates the type of welding position the electrode can be used in
What is the primary advantage of using DC welding over AC welding?
It is preferred by industrial welders
What is the primary purpose of the flux in Submerged Arc Welding (SAW)?
To provide a path for the current
What is the result of the molten flux rising to the surface of the weld in SAW?
It solidifies as a glass-like covering for the weld bead
What is the primary advantage of using Submerged Arc Welding (SAW) over manual or semi-automatic welding?
It is faster and more efficient
What is the purpose of post-weld heat treatment (PWHT)?
To relieve internal stresses in the weld metal
What is the term used to describe the process of making steel harder by heating and then quenching (rapidly cooling) it?
Quenching
What is the primary difference between the electric arc in SAW and other arc welding processes?
The arc is shielded by a granular flux
What is the purpose of the valve protection caps on the cylinders?
To protect the valve from damage
What is the primary difference between DC and AC current in SAW?
DC is used for welding with a constant voltage, while AC is used for welding with a drooping voltage
What is the purpose of the steel wool in starting the arc in SAW?
To facilitate the ignition of the arc
What is the primary advantage of using multiple electrodes in SAW?
It increases the welding speed
What is the primary reason why a weld joint becomes hard and brittle after welding?
Due to rapid cooling of the heat affected zone
What is the purpose of post-weld heat treatment in welding boilers and pressure vessels?
To relieve the stresses in the weld joint
What is the effect of rapid cooling on the heat affected zone during welding?
It makes the weld joint more brittle
What is the purpose of preheating the weld joint during welding?
To reduce the temperature gradient between the heat affected zone and the parent metal
What is the result of tempering a hardened cutting tool?
It becomes more ductile
What is the primary reason why boilers and pressure vessels are prone to sudden failures?
Due to the brittle nature of the weld joints
What is the purpose of the ASME codes in relation to boilers and pressure vessels?
To provide guidelines for welding and fabrication
What is the effect of quenching on the hardness of steel?
It makes the steel harder
What is the primary advantage of using post-weld heat treatment in welding boilers and pressure vessels?
It increases the ductility of the weld joint
What is the purpose of heating the entire weld joint to a specific temperature during post-weld heat treatment?
To restore the ductility of the weld joint
What is the main characteristic of fillet welds?
They have parent material behind the weld puddle.
What is the purpose of the small short welds in a groove weld?
To hold the work pieces in position while the material is being welded.
What type of joint is used to attach nozzles and firetube tubesheets to boiler shells?
Tee joint
What is the advantage of fillet welds over groove welds?
They are easier to perform because they have backing material.
What is the purpose of machining the edges of the work pieces in a groove weld?
To ensure the edges are smooth and match in contour.
What is the characteristic of a butt joint?
It connects work pieces that have their thicknesses centered in-line.
What is the term used to describe a weld joint that is welded from both sides?
Double-welded
What is the purpose of the root face in a groove weld?
To provide additional parent material at the root
What is the minimum requirement for the weld joint according to ASME 1 PW-9.1?
Full penetration butt welds
What is the purpose of machining the weld joint surfaces?
To achieve full penetration
What is the most common form of weld preparation used for welding lengths of high-pressure pipe?
V-groove
What is the term used to describe the distance the root extends to the back side of the parent metal?
Root penetration
What is the purpose of cleaning the weld surface after each pass?
To remove slag particles
What is the result of inadequate weld joint preparation?
Poor quality root pass
What is the advantage of using double-welded joints compared to single-welded joints of the same thickness?
Reduced parent material distortion
What is the term used to describe the process of the weld metal joining with the parent metal?
Fusion
What is the primary purpose of a strength weld in a pressure vessel?
To ensure the vessel's integrity and safety
What is the significance of a certified pressure welder in boiler and pressure vessel construction?
They have thousands of hours of documented welding time and have passed a welding performance test
What type of joints are welded from one side of the parent metal in a double-welded joint?
Passes 1-7
What is the purpose of a seal weld in a boiler or pressure vessel?
To prevent leakage
What is the primary characteristic of a welded joint in a pressure vessel?
It is as strong as the parent metal
What is the purpose of the ASME code in relation to boilers and pressure vessels?
To ensure the vessel's integrity and safety through welding and fabrication procedures
What is the primary purpose of staybolts in a boiler?
To support flat surfaces in close proximity to one another
What is the significance of the coupons in a welding performance test?
They are used to test the weld joint's integrity
What is the purpose of the seal welds applied to expanded tube attachments in a boiler?
To prevent leakage
What type of welds are critical to the strength, safety, and longevity of a boiler?
Pressure boundary welds
What is the primary purpose of a nozzle attachment in a boiler or pressure vessel?
To attach fittings or piping
What is the purpose of the weld beads applied to handhole openings in a high-pressure boiler?
To prevent leakage
What is the significance of modern quality assurance procedures in welded fabrication?
They are used to ensure the vessel's integrity and safety
What is the purpose of the pressure boundary seal welds in welded fin tube waterwall panels?
To prevent flue gas, ash, and soot leakage
What is the purpose of the lifting lugs welded to the top of the steam drum in a boiler?
To enable easy transportation and installation
What is the purpose of the manhole flue welded to the front head of the steam drum in a boiler?
To enable easy access for inspection and maintenance
What is the purpose of the manhole flue in a boiler?
All of the above
What type of weld is used to secure the tube stub in place when attaching tubes to a header?
Groove weld
What is the purpose of a repad in a pressure vessel?
To stiffen the area of the shell weakened by the hole
What is the purpose of stays and staybolts in a boiler?
To prevent flat boiler or pressure vessel surfaces from bulging due to the effects of pressure
What type of weld is used to attach a manhole flue to a shell?
Full penetration groove weld
What is the purpose of a diagonal stay in a firetube boiler?
To tie flat surfaces to other supporting structures
What is the purpose of a through stay in a firetube boiler?
To provide additional support for the water-wetted tubesheet surfaces
What is the purpose of the ASME code in relation to boilers and pressure vessels?
To provide guidelines for the fabrication and installation of boilers and pressure vessels
What is the purpose of a handhole in a boiler?
To provide access to smaller parts, such as headers and waterlegs
What type of weld is used to attach a staybolt to a boiler?
Fillet weld
What is the primary advantage of having backing material in fillet welds?
It prevents the heat of the arc from burning through the parent metal.
What is the purpose of machining the edges of parent metal pieces before making a groove weld?
To smooth the edges and match them in contour.
What type of joint is used to attach nozzles and firetube tubesheets to boiler shells?
Tee joint
What is the purpose of making small short welds to hold the work pieces in position during groove welding?
To hold the work pieces in position while being welded.
What is the primary difference between groove welds and fillet welds?
The presence of backing material.
What is the purpose of setting the work pieces apart by the approximate thickness of the welding rod during groove welding?
To allow for the correct size of the weld puddle.
What is the purpose of the weld bead in Figure 29?
To help prevent leakage between the handhole and the boiler shell
What is the primary purpose of the seal welds in Figure 28?
To prevent leakage between the tube and the shell
What is the purpose of the manhole flue in the front head of the steam drum shown in Figure 27?
To provide access to the drum for maintenance
What is the purpose of the lifting lugs on the top of the steam drum shell in Figure 27?
To enable the drum to be lifted during transportation and installation
What is the purpose of the riser tube stubs on the side of the steam drum in Figure 27?
To connect the drum to the tubes of the boiler
What is the purpose of the pressure boundary seal welds in the waterwall panels shown in Figure 31?
To prevent flue gas, ash, and soot leakage from the furnace into the boiler room
What is the purpose of the manhole flue in a boiler?
To reinforce the shell where the manhole opening is and provide a flat surface for the manhole cover plate to seal against
What is the purpose of the repad in the vessel shown in Figure 24?
To provide additional reinforcement to the shell
What is the purpose of the tell-tale hole in the repad?
To show if the pressure vessel weakens and fails beneath the repad
What type of welds are used to secure the tube stub in place?
Groove welds
What is the purpose of the stays in a boiler?
To prevent flat boiler or pressure vessel surfaces from bulging due to the effects of pressure
What is the purpose of the through stays in a firetube boiler?
To provide support for the water-wetted tubesheet surfaces
How are the stays typically fastened to the tubesheets?
By welding
What is the purpose of the yoke in a boiler?
To hold the cover plate in place
What type of welds are used to attach the manhole flue to the shell?
Full penetration groove welds
What is the purpose of the handholes in a boiler?
To provide access to smaller parts such as headers and waterlegs
What is the primary purpose of the root face in a weld groove?
To provide additional parent material at the root
What is the consequence of not achieving full penetration in a weld joint?
The weld joint will have a poor quality root, affecting its integrity
What is the purpose of the 'V-groove' weld preparation?
To allow for single-sided welding of thick materials
What is the primary purpose of a certified pressure welder in the fabrication or repair of a boiler or pressure vessel?
To perform all weld joints on the pressure boundary of the vessel
What is the advantage of using double-welded joints over single-welded joints for thicker materials?
They reduce parent material distortion and residual stress
What is theterm for the metal components that directly restrain forces that arise due to the vessel’s internal pressure?
Pressure boundary
What is the purpose of machining the weld joint surfaces in a double-welded joint?
To facilitate welding from both sides
What is the purpose of the groove angle in a weld preparation?
To ensure full penetration of the weld metal
What is the typical method of attaching nozzles to shells and headers in a boiler or pressure vessel?
Welded attachments
What is the result of inadequate fusion in a weld joint?
The weld joint will have a weak bond between the weld metal and the parent metal
What is the purpose of cleaning the weld surface after each pass?
To remove slag particles and prevent them from being embedded in subsequent passes
What is the primary advantage of using modern welded fabrication techniques in constructing boilers and pressure vessels?
They can produce joints that are as strong as, if not stronger than, the parent material
What is the term used to describe the distance the root extends to the back side of the parent metal?
Root penetration
What is the purpose of the x-ray test in the certification process of a pressure welder?
To inspect the internal structure of the weld joint
What is the purpose of the root pass in a weld joint?
To fuse the metal at the root of the joint
What is the term for the type of weld joint that is designed to be as strong as the parent material?
Strength weld
What is the purpose of the welding performance test in the certification process of a pressure welder?
To evaluate the welder's ability to follow a specific procedure
What is the consequence of not having adequate inter-pass fusion in a weld joint?
The weld joint will have a lack of strength between subsequent passes
What is the primary purpose of the ASME code in the construction of boilers and pressure vessels?
To provide guidelines for the fabrication of boilers and pressure vessels
What is the term for the process of attaching nozzles or fittings to the shell or header of a boiler or pressure vessel?
Attachments
Test your knowledge of the importance of proper welding techniques and their impact on the strength and durability of structures. Learn how improper welding can lead to weakened structures, distortion, and even failure. Assess your understanding of the critical role of sound engineering practices in weld joint design.
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