3rd Class Power Engineering - B1 - Part 3 Exam Questions and Answers Solved Correctly Rated A+
What are 'Toe Cracks' in welds? - Answers - Occur when the face of the weld terminates at the surface
of the parent metal
- Thermal stresses are very high at this point and cracking often occurs in a direction normal to the
parent
What is 'Underbead Cracking' as a welding defect? - Answers - Occurs in either the weld or the heat
affected zone
Lamellar Tears? - Answers - Cracks that occur due to high restraint and high residual stress
- They appear on the interface of the weld and the base metal, or completely in the base metal
Planar type defects, such as cracks and lack of fusion, pose high risk for metal failure. Pores and non-
metallic inclusions on the other hand, are rounded and pose less of a potential for failure. True or False?
- Answers True.
What are the 3 types of defects that NDE testing is used for in the pressure equipment industry? -
Answers 1) Inherent defects: defects that are created during the initial production of the material
2) Processing Defects: defects created in the metal during the construction of the pressure equipment
3) Service Defects: defects created during the service of the equipment
4 most common types of NDE testing? - Answers - Liquid Penetrate Testing
- Magnetic Particle Testing
- Radiographic Testing
- Ultrasonic Testing
What is a prerequisite for a material to be tested using Liquid Penetrate testing? - Answers - Flaws must
be open to the surface
- The examined surface cannot be rough or porous, since these conditions interfere with the PT
inspection
What is Capillary Action, and how does it relate to Dye Penetrate testing? - Answers - Cohesive forces
between the liquid and the straw are greater than the cohesive forces within the liquid itself
Other than Capillary Action, what is another principle that affects Penetrate Testing? - Answers - The
ability of the liquid to migrate and wet over the surface of the material
- Migration depends on the surface tension and contact angle of the material
,The liquid penetrant must not only be able to penetrate the material, but also withdraw from the
material after inspection. True or False? - Answers True
4 types of possible materials Liquid Penetrant testing works for? - Answers Materials that are welded,
cast, rolled or forged
In brief, list the 6 major steps in Liquid Penetrant Testing. - Answers 1) Pre Cleaning
2) Penetrant application
3) Excess Penetrant Removal
4) Developer Action
5) Inspection/Interpretation
6) Post-Cleaning
Cleaning surfaces before Liquid Penetrant Testing? - Answers - Use solvents or degreases to remove any
contaminants
2 means of applying Penetrant (dye)? - Answers Spraying or Brushing
Visible Penetrants? - Answers - Defects can be seen using normal incandescent light
Fluorescent Penetrants? - Answers - Require ultraviolet light to see the defects
Removing Excess Penetrant? - Answers A solvent or water is used to remove excess penetrant from the
surface, leaving penetrant in the defects only
Developer Action in LP testing? - Answers - A developer is a chemical that draws the penetrant out of
the defects and reacts with the penetrant to produce an outline of the defect
- Developer is sprayed onto the surface forming a consistent, even coating
Post Cleaning after LP testing? - Answers - Clean penetrant and developer of the test material being
careful not to remove any defect markings
Magnetic Particle Testing? - Answers - NDE technique that detects surface or sub-surface flaws
- Can only be applied to ferromagnetic materials
Working principle behind Magnetic Particle Testing? - Answers - Magnetic flux in a material is distorted
by any defects
- Distortion is greatest when the defect is perpendicular to the magnetic field
- A pair of magnetic poles, which act as magnets, are created if the distortion of the magnetic field is
great enough
, What is the purpose of the magnetic particles in MT? - Answers - Magnetic particles are attracted to the
poles created in the defective surface, indicating the location of the defect
- Magnetic particles either come Wet or Dry, and in various colours to aid in distinction
Magnetic Particle Testing can be used on ferromagnetic pressure components that are welded, cast,
rolled or forged, and typical defects found are Lack of Penetration and Cracks. True or False? - Answers
True.
6 general steps to Magnetic Particle Testing? - Answers 1) Pre-cleaning the surface
2) Magnetizing the component
3) Applying the magnetic particles
4) Interpretation
5) Post-demagnetization of the component
6) Post-Cleaning
Magnetizing the test piece in a MT? - Answers - A longitudinal magnetic field is established by placing an
electromagnetic yoke in contact with the test material and energizing the coil of the electromagnet
Applying the magnetic particles in a MT? - Answers Dry Method: Dry Iron oxide particles are spread in
the surface
Wet Method: Magnetic Iron oxide particles are held in a carrier liquid, such as kerosene, and the liquid is
sprayed or painted onto the surface
Post-demagnetization of the component in a MT? - Answers - AC current is applied to the test piece
after the defects have been marked
- De-magnetization is done with a special tool to prevent damage to moving parts, arc deflection during
welding, interference with machining and interference with coating or painting
Radiographic Testing identifies defects that are internal to the weld or base metal. True or False? -
Answers True
Principle behind Radiographic Testing? - Answers - Different amounts of penetrating radiation are
absorbed in good material that in defective material
- Unabsorbed radiation passes through the test material and exposes film on the opposite side
X-rays v.s. Gamma rays? - Answers - Only differ in ways which they are produced
- X-rays: Produced when high speed electrons strike a metal target, causing a transfer of energy
What are 'Toe Cracks' in welds? - Answers - Occur when the face of the weld terminates at the surface
of the parent metal
- Thermal stresses are very high at this point and cracking often occurs in a direction normal to the
parent
What is 'Underbead Cracking' as a welding defect? - Answers - Occurs in either the weld or the heat
affected zone
Lamellar Tears? - Answers - Cracks that occur due to high restraint and high residual stress
- They appear on the interface of the weld and the base metal, or completely in the base metal
Planar type defects, such as cracks and lack of fusion, pose high risk for metal failure. Pores and non-
metallic inclusions on the other hand, are rounded and pose less of a potential for failure. True or False?
- Answers True.
What are the 3 types of defects that NDE testing is used for in the pressure equipment industry? -
Answers 1) Inherent defects: defects that are created during the initial production of the material
2) Processing Defects: defects created in the metal during the construction of the pressure equipment
3) Service Defects: defects created during the service of the equipment
4 most common types of NDE testing? - Answers - Liquid Penetrate Testing
- Magnetic Particle Testing
- Radiographic Testing
- Ultrasonic Testing
What is a prerequisite for a material to be tested using Liquid Penetrate testing? - Answers - Flaws must
be open to the surface
- The examined surface cannot be rough or porous, since these conditions interfere with the PT
inspection
What is Capillary Action, and how does it relate to Dye Penetrate testing? - Answers - Cohesive forces
between the liquid and the straw are greater than the cohesive forces within the liquid itself
Other than Capillary Action, what is another principle that affects Penetrate Testing? - Answers - The
ability of the liquid to migrate and wet over the surface of the material
- Migration depends on the surface tension and contact angle of the material
,The liquid penetrant must not only be able to penetrate the material, but also withdraw from the
material after inspection. True or False? - Answers True
4 types of possible materials Liquid Penetrant testing works for? - Answers Materials that are welded,
cast, rolled or forged
In brief, list the 6 major steps in Liquid Penetrant Testing. - Answers 1) Pre Cleaning
2) Penetrant application
3) Excess Penetrant Removal
4) Developer Action
5) Inspection/Interpretation
6) Post-Cleaning
Cleaning surfaces before Liquid Penetrant Testing? - Answers - Use solvents or degreases to remove any
contaminants
2 means of applying Penetrant (dye)? - Answers Spraying or Brushing
Visible Penetrants? - Answers - Defects can be seen using normal incandescent light
Fluorescent Penetrants? - Answers - Require ultraviolet light to see the defects
Removing Excess Penetrant? - Answers A solvent or water is used to remove excess penetrant from the
surface, leaving penetrant in the defects only
Developer Action in LP testing? - Answers - A developer is a chemical that draws the penetrant out of
the defects and reacts with the penetrant to produce an outline of the defect
- Developer is sprayed onto the surface forming a consistent, even coating
Post Cleaning after LP testing? - Answers - Clean penetrant and developer of the test material being
careful not to remove any defect markings
Magnetic Particle Testing? - Answers - NDE technique that detects surface or sub-surface flaws
- Can only be applied to ferromagnetic materials
Working principle behind Magnetic Particle Testing? - Answers - Magnetic flux in a material is distorted
by any defects
- Distortion is greatest when the defect is perpendicular to the magnetic field
- A pair of magnetic poles, which act as magnets, are created if the distortion of the magnetic field is
great enough
, What is the purpose of the magnetic particles in MT? - Answers - Magnetic particles are attracted to the
poles created in the defective surface, indicating the location of the defect
- Magnetic particles either come Wet or Dry, and in various colours to aid in distinction
Magnetic Particle Testing can be used on ferromagnetic pressure components that are welded, cast,
rolled or forged, and typical defects found are Lack of Penetration and Cracks. True or False? - Answers
True.
6 general steps to Magnetic Particle Testing? - Answers 1) Pre-cleaning the surface
2) Magnetizing the component
3) Applying the magnetic particles
4) Interpretation
5) Post-demagnetization of the component
6) Post-Cleaning
Magnetizing the test piece in a MT? - Answers - A longitudinal magnetic field is established by placing an
electromagnetic yoke in contact with the test material and energizing the coil of the electromagnet
Applying the magnetic particles in a MT? - Answers Dry Method: Dry Iron oxide particles are spread in
the surface
Wet Method: Magnetic Iron oxide particles are held in a carrier liquid, such as kerosene, and the liquid is
sprayed or painted onto the surface
Post-demagnetization of the component in a MT? - Answers - AC current is applied to the test piece
after the defects have been marked
- De-magnetization is done with a special tool to prevent damage to moving parts, arc deflection during
welding, interference with machining and interference with coating or painting
Radiographic Testing identifies defects that are internal to the weld or base metal. True or False? -
Answers True
Principle behind Radiographic Testing? - Answers - Different amounts of penetrating radiation are
absorbed in good material that in defective material
- Unabsorbed radiation passes through the test material and exposes film on the opposite side
X-rays v.s. Gamma rays? - Answers - Only differ in ways which they are produced
- X-rays: Produced when high speed electrons strike a metal target, causing a transfer of energy
