48 Questions
What does the designation 'A' indicate in the context of heat treatment?
As-welded condition
What does the designation 'EC' indicate in the classification of electrodes?
Composite electrode
What does the designation 'F7A6-EM12K' refer to?
Flux and electrode combination for specific weld properties
What does the designation '20 ft·lb [27J]' represent in the context of weld metal impact strength?
Minimum impact strength
What should be done to a cylinder when transported to prevent it from turning into a lethal missile?
Remove the regulators and cover the valves with special screw-on caps
What type of heat source does oxyacetylene welding (OAW) provide?
Less concentrated heat source compared to an arc
What type of joint preparation is recommended for making a groove weld using OAW?
Exhibit a thin 'feather edge'
What type of welding is OAW best suited for?
Thin section welding
What skill level is required for oxyacetylene welding (OAW) to achieve best results?
Substantial skill level
What problems are primarily associated with oxyacetylene welding (OAW)?
Improper manipulation or adjustment of the flame
What is the mixing section of the torch used for in oxyacetylene welding (OAW)?
To combine oxygen and acetylene to provide the necessary mixture
What type of flame is recommended for carbon steel welding using oxyacetylene welding (OAW)?
Neutral flame
What is the tensile strength of weld metal produced by Submerged Arc Welding (SAW)?
70,000 psi
What is the Charpy V-notch requirement for weld metal produced by SAW at –40°F?
20 ft·lb
What is a characteristic of Submerged Arc Welding (SAW) regarding smoke generation?
Low smoke generation
What is a limitation of Submerged Arc Welding (SAW) in terms of welding positions?
Can only be done in positions where flux can be supported
What is a requirement for finished welds produced by Submerged Arc Welding (SAW)?
They have a layer of solidified slag that must be removed
What is a benefit of Submerged Arc Welding (SAW) in terms of material surfaces?
It provides improved corrosion or wear resistance
What is a characteristic of the operator appeal of Submerged Arc Welding (SAW)?
Lack of visible arc and less smoke generation
What is the method used by semiautomatic Submerged Arc Welding (SAW) to deliver flux to the welding gun?
Compressed air
What type of electrode is used in Plasma Arc Welding (PAW) to create an intense plasma region?
Tungsten electrode
How does the intensity of the plasma region in Plasma Arc Welding (PAW) compare to Gas Tungsten Arc Welding (GTAW)?
PAW has a more intense plasma region
What is a similarity between Plasma Arc Welding (PAW) and Gas Tungsten Arc Welding (GTAW)?
Type of power source used
What is a characteristic of mechanized systems in Submerged Arc Welding (SAW)?
They distribute flux ahead of the arc
What is the primary limitation of Electroslag Welding (ESW)?
Extensive time required for setup
What problem may occur if the current levels are too high in Electroslag Welding?
Copper orifice melting
What is the primary advantage of Electroslag Welding (ESW)?
High deposition rate
What is the primary function of acetylene in oxyacetylene welding?
Fuel for high-temperature welding
What type of welding method is oxyacetylene welding considered to be?
Chemical welding method
What is the primary advantage of oxyacetylene welding?
Relatively inexpensive and portable equipment
What is the purpose of the pressure regulators in oxyacetylene welding equipment?
To reduce high internal tank pressure to working pressure
What is the primary disadvantage of oxyacetylene welding?
Limited application for thinner sections
What does the identification 'RG-45' signify in oxyacetylene welding?
Minimum tensile strength of the weld deposit
What is the primary advantage of using metal strip instead of wire in Electroslag Welding?
Increased deposition rate
What problem may occur due to the presence of a leak in one of the water-cooled shoes in Electroslag Welding?
Gross porosity
What is the primary task of oxyacetylene welding?
Welding thin steel sheet and small diameter steel piping
What is the primary fuel gas used in oxyacetylene welding (OAW)?
Acetylene
Which welding process has the highest deposition rate among welding processes?
Electroslag welding (ESW)
What is the major advantage of Electroslag welding (ESW)?
High deposition rate
What is the primary advantage of Oxyacetylene welding (OAW)?
Portability
What is a potential problem associated with Electroslag welding (ESW)?
Tungsten inclusions
What type of material is Oxyacetylene welding (OAW) used for welding?
Steel
What is a characteristic of Oxyacetylene welding (OAW) equipment?
Consists of oxygen and acetylene tanks
What problem is associated with Oxyacetylene welding (OAW)?
Gross porosity
What is the primary limitation of Electroslag welding (ESW)?
Uneconomical for thinner sections
What type of welding method is Oxyacetylene welding (OAW) considered to be?
Chemical welding
What is the filler material used for Oxyacetylene welding (OAW) primarily used for?
Welding thin steel sheet
What is the primary problem associated with Electroslag welding (ESW) in terms of setup?
Excessive time required for setup
Study Notes
Submerged Arc Welding and Plasma Arc Welding Processes
- Submerged Arc Welding (SAW) produces weld metal with a tensile strength of at least 70,000 psi and Charpy V-notch of at least 20 ft·lb at –40°F
- SAW has high deposition rate, less smoke generation, and deep penetration ability but can only be done in positions where flux can be supported
- SAW requires extensive fixturing and positioning equipment, and finished welds have a layer of solidified slag that must be removed
- The process has inherent problems related to granular flux, welding current choice, and solidification cracking
- SAW is beneficial for overlaying or building up material surfaces, providing improved corrosion or wear resistance
- SAW process has high operator appeal due to lack of visible arc and less smoke generation
- The flux in SAW prevents the welder from seeing the arc's position, requiring tracking of the joint without the arc or the flux
- Semiautomatic SAW uses compressed air to force the flux to the gun, while mechanized systems distribute the flux ahead of the arc or around the arc from a nozzle
- Plasma Arc Welding (PAW) creates an intense plasma region using a tungsten electrode and a copper orifice within the ceramic nozzle
- PAW is similar to Gas Tungsten Arc Welding (GTAW) in equipment but differs in the intensity of the plasma region
- Both PAW and GTAW use the same type of power source and shielding gas
- PAW has a more concentrated and intense arc compared to GTAW due to the constriction of the arc caused by the plasma gas forced through the orifice
Welding Processes Overview
- Electroslag welding (ESW) is primarily used by industries dealing with heavy weldments and has the highest deposition rate among welding processes.
- ESW can encounter problems such as tungsten inclusions from high current levels and tunneling from incomplete filling of the keyhole.
- ESW may lead to centerline cracks due to weld metal shrinkage and grain growth in the weld metal due to high heating.
- Oxyacetylene welding (OAW) uses acetylene as the only fuel gas capable of producing high temperatures for effective welding of steel.
- OAW does not require external shielding or flux and is considered a chemical welding method.
- OAW equipment consists of oxygen and acetylene tanks, pressure regulators, torch, and connecting hoses.
- The major advantage of ESW is its high deposition rate, and it does not require special joint preparation.
- ESW setup time and effort required for positioning workpieces and guides make it uneconomical for thinner sections despite its high deposition rate.
- ESW problems include gross porosity, detachment of tips, and extensive time required for setup.
- OAW filler material has a simple identification system, and it is used for welding thin steel sheet, small diameter steel piping, and maintenance situations.
- OAW advantages include its relative inexpensiveness, portability, and lack of electrical input requirement.
- Care should be taken when moving OAW equipment to prevent damage to the primary valves on the cylinders.
Test your knowledge of welding processes with this quiz. Explore submerged arc welding (SAW) and plasma arc welding (PAW) processes, as well as an overview of electroslag welding (ESW) and oxyacetylene welding (OAW). Learn about their characteristics, advantages, equipment, and common issues.
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