3.2u Mixed papers 2 (old) Flashcards
HP water jet finishing on painted steel structure
(Question not clear, I dont have copies of this test paper anymore)
SA3
3.4u Manual
Paints
When paint is applied to a metal surface it presents a barrier to air, moisture and ions aggressive to the metal. However, paint cannot provide a complete barrier to oxygen or water. In time these will penetrate through to the surface of the metal. Any paint system used underwater must have a strong bond onto the metal surface and therefore high quality metal surface preparation is required such as SA3. The bonding between successive coats must also be strong and the topcoats must provide as impervious a barrier to the electrolyte as is possible.
Before CP survey, Bathycorrometer should be
Answer: All of the above
A. Tested in fresh seawater
B. Tested on zinc block and unprotected steel
C. Tested at Depth
D. All of the above
Answer is D
Prior to MPI inspection, checking a permanent magnet will lift 18kg serves what purpose?
Checking that it has sufficient power to induce the field strength and meets the required standard
Magnetising Equipment: BS EN 9934-1
1 Tesla magnetising force required
The efficiency of a cathodic protection system can be assessed by
Taking readings of the electrical potential
Over-protected structure : More negative than -1100mV Zinc: -1050 mV
Protected steel: -800 to -11—mV
Under protected steel: -640 to -800mV
Unprotected steel: -450 to-640mV
Monel: -50 to-150mV
If aluminium is connected to mild steel and immersed in seawater, the aluminium will be
The anode
Galvanic Series: think of it as a superhero team where some metals are strong and don’t get hurt (noble), and others are weaker and get damaged (corrode) when facing a villain (the liquid).
Galvanic Series in seawater.
Graphite
Gold
Platinum
Silver
Stainless steel
Monel
Copper
Niobium
Tungsten
Lead
Cast iron
Mild steel
Aluminium
Zinc
Magnesium
On the pH scale which of the following values would be described as acidic
pH2.5
Therefore, any value less than 7 would be described as acidic. The lower the pH value, the more acidic the substance is. Neutral substances have a pH of 7, while values above 7 are considered alkaline or basic.
An ion is atom that has a positive , negative or both?
Has a positive or negative charge
https://youtu.be/EIAaGHK5pjA?si=euKYfYEWKOLgpWD3
An ion is an atom or molecule that has gained or lost electrons, giving it a net positive or negative electric charge. If it has more protons than electrons, it’s a positive ion or cation. If it has more electrons than protons, it’s a negative ion or anion
The Pourbaix diagram displays 2 sets of data?
Electrode potential and pH value
There are numerous methods for preventing corrosion including, coatings, inhibitors (controlling the electrolyte), selective design, anodic protection and cathodic protection. Before considering these methods a brief examination of the way in which the corrosion process is influenced by the two main variables; the electrode potential and the pH value will assist in understanding the various protection methods.
A structure protected by an ICCP system identifies a shadow area….what could be done to improve that protection for that area
Install sacrificial anode
Offshore structures use impressed current systems in preference to sacrificial systems because they
Reduce overall weight loading
A calomel cell selected from a pair to be used for calibrating a CP meter, should give what reading on a voltmeter
+-2mv
3.4u manual: Calibration Checking between calomel cells. Acceptable readings between any pair of electrodes is +/- 2mV
ICCP systems use voltage/amperage values in which range?
30-80 volts DC / 300- 1000 amps
If a keeper plate was attached to a permanent magnet, which way would the flux lines run through the keeper plate
North to South
Here’s a simplified representation of the magnetic flux lines:
North Pole (N) → Keeper Plate → South Pole (S)
When lines of magnetic force jump the gap formed by a surface-breaking defect, it is called
Flux leakage
The symbol used for magnetizing force is?
H
At the coercive point on a B/H curve, the material would:
Have zero flux density
https://youtu.be/ZyVSMfSgOq0?si=Y4ZVd1J8rkAm7C5p
What can be used to protect a steel structure against corrosion in the splash zone
Protective coatings
If an atom loses one or more electrons, this will be called
An anodic reaction
https://youtu.be/ZyVSMfSgOq0?si=P1te2lJ1YiV0_RzC
In ultrasonics, frequency is measured in ?
Hertz
In regard to digital cameras, what do the initials CCD sand?
Charge Coupled Device
Before use; a Bathycorromter should be soaked for
30 minutes in fresh seawater
What is the formula to calculate the near zone?
NZ=D² / 4λ
lambda λ = wavelength of any wave.
Post-tensioning cables are used to put concrete under which sort of stress?
Compression
Post-tensioning cables are used to put concrete under compressive stress. This technique is employed to reinforce concrete structures by introducing compressive stress to counteract the tensile forces that the structure may experience during its lifespan1. The process involves applying controlled forces to prestressed cables or tendons, which are then anchored to the concrete, resulting in increased load-bearing capacity, improved resistance to cracking, and enhanced structural performance
In a single V butt weld the angle between the two prepare faces is called
The included angle
Fatigue can be described as?
Cyclic loading and unloading on a material causing local hardening
What is the minimum cover required over the Steel reinforcement in a concrete structure
60mm
What NDT method can be used to find and size for depth of a surface breaking defect in a steel structure
ACFM
The following is a true statement with regards to digital thickness meter
It can only show the depth to a major reflector
A mid-water arch is a device that is used to
Prevent tension in a flexible riser
The fundamental purpose of monel cladding is to
Insulate the structure from electrolyte
A fatigue crack will mostly be found where?
In the toe of the weld
How many mega pixels is the minimum number required for a digital camera used in underwater photography?
6 Mega pixels
In a corrosion circuit, which of the following travels through the material from anode to cathode?
Negative Electron
Here’s a simplified representation of the process:
Anode (site of oxidation) → Electrons travel through material → Cathode (site of reduction)
The corrosion that occurs beneath a water drop on a steel plate is what type?
Pitting corrosion
A method of welding that cannot be conducted on a nodal joint is?
Submerged arc welding
Which of the following is classed as a planar defect?
Lamination
A planar defect in metal is a type of imperfection that occurs across a plane within the crystalline structure of the material. These defects are two-dimensional and typically separate regions of the material that have different crystal structures or orientations.
A lamination defect in metal is a type of planar defect that consists of flat and thin subsurface separations inside a metal plate, parallel to the surface of the plate. This defect is considered a serious discontinuity that can originate during hot or cold forming processes
If a steel pipe which had an electrical potential of -520mV was placed in an electrolyte with a pH of 11.5 what would happen to it?
It would not corrode due to passivation
Rfere to the Pourrbaix diagram
In an ICCP system, the structure is the?
A cathode and negative
Which of the following statements describes the term Coercivity?
The amount of magnetizing force in the opposite direction required to bring the flux density to zero.
https://youtu.be/ZyVSMfSgOq0?si=DKf1af66sQVt8z61
When conducting an MPI inspection using an electromagnetic yoke,what is the extent of the valid inspection area?
Half the distance either side of the pole seperation.
Electromagnets produce a longitudinal field with the test area being a circle inscribed by the poles. Defect orientation is the same as when using a permanent magnet. BS EN ISO 9934-1 states that a lift test should be carried out prior to using for MPI. The lift test should confirm that the electromagnet can lift 4.5kg with a pole spacing of up to 300mm.
In mercury vapour lamps a Woods Filter is used to prevent which of the following getting through?
UVB wavelengths
Remeber: UVB: B for Bad…so UVA is better (safer)
The wavelength of a UV light used to view MPI indications is?
365-400nm
Light BS EN ISO 3059
Day / Black Ink / 500 lux
Night / fluorescent /20 Lux
UV 1000 μW / cm2 @ 365-400nm wavelength
Which of the following would require the most lines of flux if all were subjected to the same amount of magnetizing force?
Nickel
Magnetic flux lines travelling from steel into iron would do what?
Gather closer together
Magnetic flux lines represent the strength and direction of a magnetic field. When they travel from steel into iron, they gather closer together because iron has a higher magnetic permeability compared to steel. This means iron can more easily support the development of a magnetic field within itself. As a result, the magnetic field lines are denser or more concentrated in iron, indicating a stronger magnetic field in that region
The type of magentism produced by a horseshoe magnet is?
Longitudinal
The volume of a settlement flask sample for MPI ink is?
100ml
Ink BS EN ISO 9934-2
Settlement / Suntherland = 100ml / 60 min
Ferrous Oxide 0.1% - 0.3% by volume
Additives no more than 10% by weight
Which of the following statements concerning magnetic lines of flux is correct?
The lines all have the same strenght
In an ICCP system, what does a dielectric shield prevent?
High density current flowing directly into the structure
During an MPI inspection of a nodal weld using AC yoke, which of the following would not be detected?
A lamination running parallel to the weld
In an ICCP system, what is a shadow area?
An area of inadequate cathodic protection
By multiplying the RMS figure by 1.414, the sum will be the value of?
The peak current AC
Multiplying the RMS (Root Mean Square) value by 1.414 (which is the square root of 2) gives you the peak value of an alternating current.
Which of the following is an advantage of a single crystal probe over a twin crystal probe?
Greater penetration
Single Crystal probe:
Advantages:
Good Power Output
Greater Penetration
Disadvantages:
Poor near zone resolution
Cannot measure thin plate
Twin Crystal Probe
Advantages
Good near zone
Measure thin plate
Disadvantages
Less Power Output
Less penetration
The corrosion rate of an unprotected steel structure in seawater will increase if?
The water temperature increases
An offshore structure that is supported on the seabed by its own weight is termed?
A gravity structure
On a jacket, which of the following best describes the term batter?
The angle of the legs to the vertical
Vortex shedding causes what type of defect?
Scour
Which of the following items would not be required to conduct a CVI of a nodal weld?
A flux indicator
Altering the frequency of an ultrasonic probe will affect which of the following parameters?
The wavelenght
Yes, altering the frequency of an ultrasonic probe will affect the wavelength. The relationship between frequency and wavelength is inversely proportional, meaning that as the frequency increases, the wavelength decreases, and vice versa.
When you flick a long ruler hanging off a desk, it vibrates slowly (low frequency, long wavelength). A short ruler flicked the same way vibrates quickly (high frequency, short wavelength).
With regards to inspecting concrete structures; variable cover is what kind of defect?
A Category, a construction defect
Dynamic loading is based on?
Normal wave and wind spectrum
0.5 to 1.5MHz ultrasonic probes are used for testing which of the following?
Concrete and cast iron
Which of these techniques cannot be used to determine the depth of a surface-breaking defect
Eddy Current
In a digital camera what is a CCD
An image sensor
A CCD, or Charge-Coupled Device, is an electronic sensor used in digital cameras to capture light and convert it into digital signals.
Which action does the shutter speed control
How long the aperture is open
What is backscatter ?
Light reflecting from particles in the water
Why would a photo mosaic be completed?
If access is restricted for any other method
What is a picture grab?
A still taken from video
Which of the following affects the field of view?
Focal lenght
Welding joins metal together by?
Electro chemical reaction
Typically how many joint configurations are seen on offshore structures?
2
2 (check)
Where is the HAZ to be found?
In the parent plate adjacent to adjacent to the weld
What will Hydrogen diffusing into the parent plate cause?
Embrittlement
Cracks in welds are ?
2 dimensional
Cracks in welds are typically considered two-dimensional (2D) defects because they manifest along a plane or surface. Unlike volumetric defects, such as porosity or inclusions, which extend into the material in three dimensions, cracks are more confined to a specific plane within the weld.
A stray flash is also known as ?
Arc strike
The angle of incidence is……….?
Equal to the angle of reflection
What should be reported when carrying out an anode inspection?
Anode size
What would cause spurious indication in MPI?
Answer: Dirt or scale
a. Grinding mark
b. Dirt or scale
c. Toe undercut
d. Poor cap profile
Another name for preferential corrosion is
Weld decay
Weld decay or preferential corrosion is an example of this type of decay. In this case the boundary is the fusion boundary that forms along the toe of the weld and is a region of higher energy. This region becomes the
anode and corrosion sets in, often giving quite significant visual indications of its presence.
In Photography: What can produce a narrower field of view
Increase the focal length of the lens
In photography, using a lens with a longer focal length will produce a narrower field of view. A longer focal length lens magnifies the image and captures a smaller portion of the scene, resulting in a more zoomed-in or telephoto view.
Iridium 192 is a gamma radiation source for
Weld inspection of plate up to 50mm
Assuming you have access to both sides of a weld, which of the following defects could not be found during a visual inspection?
Answer: Lack of inter-run fusion in a single V butt weld
a. Lack of inter-run fusion in a single V butt weld
b. Lack of root penetration in a single bevel butt weld
c. Lack of root penetration in a single V butt weld
d. Lack of sidewall fusion and incompletely filled groove
ACFM cleaning standard
SA2
ACDP cleaning standard
SA 2.5
Eddy current cleaning standard
SA 2
Radiography cleaning standard
SA 1
FMD cleaning standard
SA 2
Note: No cleaning reuired when Assessing the integrity of tubular members with Caesium 137 only used by ROV
…….is an example of in service defect?
Poor repair
……….is an example of a construction defect
Tearing
……….is an example of a construction defect
Honeycombing
……….is an example of a construction defect
Blowholes
The following statement concerning weld defects is true
Poor stop start is an imperfect shape defect
The cathodic reaction is also known as?
Reduction
Remember:
ANOX REDCAT
Anode =Oxidation
Reduction = Cathode
OILRIG
Oxidation is Loss of Electrons, Reduction is gain of electrons
Changing f-stop from f8 to f11 will produce what effect
Half the amount of light entering the camera
Increasing the f-stop from f/8 to f/11 will decrease the size of the lens aperture, resulting in a smaller opening. This change will increase the depth of field in your photograph, making more of the scene in focus. However, it also reduces the amount of light entering the camera, so you may need to adjust other settings, like ISO or shutter speed, to maintain proper exposure.
Which focal length will give a wider field of view
A shorter focal length will provide a wider field of view. So, for example, a 24mm lens will generally have a wider field of view compared to a 50mm lens.
Which of the following is the correct description of delamination?
A Category in service defect
…….is an in-service planar defect
A fatigue crack
What is a planar defect?
These have a large surface area but small volume such as cracks and
laminations. They are essentially 2 dimensional.
What is a volumetric defect
Inclusions, porosity and other internal flaws that have a large volume
compared to surface area are in this category. They are 3 dimensional and
will also include undercut and lack of penetration. This category of defect is
caused during fabrication, not in-service; while planar defects may be
caused by in-service deterioration.
A Bathycorromter reading of -845mV would indicate?
The structure is cathodically protected
ACFM combines which of the following pairs of techniques to determine the length and depth of a surface breaking defect?
Eddy current and ACPD
Vibrations in a platform leg, which are at 90 degrees to the tidal current flow is caused by
Vortex shedding
A vertical steel pipe that carries crude away from a production platform is called a?
Export riser
A reddish brown stain is seen during a visual inspection of a concrete structure it should be ?
Reported
A binding agent in concrete is which of the following
Cement
A fatigue crack will most likely be found in ?
The weld toe
In a concrete structure,what prevents the steel reinforcement from corroding?
The high pH
The electrical current produced in an electrolyte between two metals would be strongest between?
Silver and Aluminium
Galvanic Series in seawater.
Noble Top
Graphite
Gold Platinum
Silver
Stainless steel
Monel
Copper
Niobium
Tungsten
Lead
Cast iron
Mild steel
Aluminium
Zinc
Magnesium
Less Nobble bottom
Anything less noble than steel will corrode to protect the steel
The following metal in contact with steel in an electrolyte could cause the steel to corrode?
Copper
Galvanic Series in seawater.
Graphite
Gold
Platinum
Silver
Stainless steel
Monel
Copper
Niobium
Tungsten
Lead
Cast iron
Mild steel
Aluminium
Zinc
Magnesium
CP reading in contact with unprotected steel in seawater?
-450mmV to -640mV
Assuming the surface is cleaned down to bare metal, which of the following cannot be found by visual inspection of the weld
Lack of sidewall fusion
Name a property of the magnetic lines of flux?
They follow the path of least resistance
A magnetic field is strongest where?
The lines of flux are packed closely together
A material is said to be saturated when?
An increase in H (force) produces no increasing B (flux density)
Which of the following could give rise to a leakage field during MPI?
- A sharp change in the magnetic permeability
- A sharp change in the components geometry
e - A crack running at 90deg to the magnetic flux lines
All of the above
The following statement about the use of a permanent magnet for MPI is true
They have a high Coercivity
Low Permeability (Hard Ferromagnetic)
(Difficult to Magnetise)
High Retentivity
High Remanence
High Reluctance
High Coercivity
High Permeability (Soft Ferromagnetic) (Easily Magnetised)
Low Retentivity
Low Remanence
Low Reluctance
Low Coercivity
Magnetic poles are ?
Points on a magnet where the flux lines enter or leave
A field indicator is an instrument which can be used to?
Check for residual magentism
The strength of an AC electromagnetic yoke is assessed by:
Measuring it’s lifting power.
The requirement is that the electromagnet must be able to lift 4 ½ kilograms
with pole spacing up to 300 mm
BS EN ISO 9934-1
In its simplest form an atom is a positive a positive nucleus surrounded by electrons. What charge re these electrons?
Negative
https://youtu.be/2LEkjDiGcWw?si=Y63oTGI3-5BMb28L
When an electron is either added or taken from the group surrounding an atom, the overall charge is no longer zero. The condition of the atom at this stage is called:
Ionic
https://youtu.be/2LEkjDiGcWw?si=Y63oTGI3-5BMb28L
If the atom loses an electron it it becomes a positive ion an has a positive charge. This may be referred to as a
Cation
https://youtu.be/EIAaGHK5pjA?si=iyqqGNvKjsx7zgW3
The following reaction occurs at the cathodic site?
Reduction
The Cathodic Reaction
These ‘free’ electrons formed in the anode reaction must be ‘used up’ if the
reaction is to proceed. This part of the reaction in the electrochemical corrosion
process therefore takes place at the site where the free electrons are
neutralised and is known as the cathodic reaction. Alternatively reactions such
as this that consume electrons are also known as reduction reactions
Remember:
ANOX REDCAT
Anode =Oxidation
Reduction = Cathode
OILRIG
Oxidation is Loss of Electrons, Reduction is gain of electrons
The anode usually corrodes because of a
Loss of electrons
Pitting is which type of corrosion?
Localised
A form of corrosion that forms along the toe of the weld due to higher energy regions is often called
Weld decay
Weld decay, or preferential corrosion, is an example of this type of decay. In this case the boundary is the fusion boundary that forms along the toe of the weld and is a region of higher energy. This region becomes the anode and corrosion sets in, often giving quite significant visual indications of its presence.
Fretting corrosion occurs at areas
Materials under
load subjected to vibration and slip.
What environmental factors affect the corrosion rate ?
Temperature
Water flow rate
The pH of the electrolyte
A working riser which become hot during service ?
Is particularly susceptible to corrosion and must be inspected more frequently
Steel corrodes least when it is submerged in an electrolyte that has a pH value between
11-12
A high pH level is described as alkaline or basic.
Describe a caisson
An open bottomed tubular component terminating at various depths for the purpose of the intake or discharge of water or waste
Tension leg platforms are held in position by?
Piled steel anchor bases and vertical tendons
FPSO stands for
Floating production and storage operations
FPSO’s can offer advantages over platforms because:
They can reach remote parts of the field inaccessible to the existing platform
They can develop a field too small to warrant the cost of a fixed platform
They can develop a wider spread field using dedicated floating production systems (FPS) and linking the wells with pipelines.
Note: All of the above
Traditional pipelines are made up of sections of what given length?
12.1m
A typical field joint is joined by what type of weld
Full penetration but weld
A typical field joint is covered in what?
Bitumen and protective wrap
What is an alternative name for an anchorage point when referring to concrete
Cachetage point
Describe a conductor
Tubes for drilling purposes connecting seabed wells to the topside
What is the purpose of a breakwater wall?
To dissipate wave energy in the splash zone
Define Permeability
Permeability has been defined as the ease with which a material can be magnetised. Of course, it is only some of the ferromagnetic group that are usefully magnetised. Those that are easy to magnetise are: -
Soft iron
Low carbon steel
Define coercive
Coercive Force
The amount of reverse magnetic field which must be applied to a magnetic
material to make the magnetic flux return to zero. (The value of H at point Hc on the
hysteresis curve).
Define reluctance
Reluctance
It is a term
used to describe the opposition that a ferromagnetic material shows to the
establishment of a magnetic field. Reluctance is comparable to the resistance in
an electrical circuit, however it does not have units while resistance does of
course. (This term is sometimes used as the opposite of permeability; low permeability would
indicate high reluctance and visa versa).
Define retentivity
Retentivity: it is a material’s ability to retain a certain
amount of residual magnetic field when the magnetizing force is removed after
achieving saturation. (The value of B at point Br on the hysteresis curve, Figure 9.11).
Magnetic poles are
Points on a magnet where the flux lines enter or leave
A field indicator instrument which can be used to:
Check for residual magnetism
The strength of an electromagnetic yoke is assessed by
Measuring it’s lifting power
Strength Required for MPI Electromagnets
BS EN ISO 9934-
1:2001.
4 ½ kilograms - pole spacing up to 300 mm.
MPI indications which appear indistinct and fuzzy as apposed to strong and well defined are often caused by?
Sub surface defects
The concentration of ferrous oxide particles in MPI can be checked by
A settlement test
Ink BS EN ISO 9934-2
Settlement / Suntherland = 100ml / 60 min
Ferrous Oxide 0.1% - 0.3% by volume
Additives no more than 10% by weight
The ferrous oxide particles concentration of fluorescent MPI ink is typically in what range?
Fluorescent Inks
Ferromagnetic particles 0.1% to 0.3% by volume
The ferrous oxide particles concentration of non- fluorescent MPI ink is typically in what range?
Non-fluorescent Inks
Ferromagnetic particles 1.25% to 3.5% by volume in the ink
