Study Questions Flashcards
Define corrosion.
Environmentally induced deterioration.
What is passivation?
The formation of a corrosion byproduct, such as oxide, chloride, carbonate, sulfate, etc., that can retardation further corrosion.
Describe what happens at the anode.
The anode is the part of the metal that actually corrodes, or dissolves into the electrolyte.
What is the function of the electrolyte?
Allows the movement of ions between the anode and the cathode. It allows anions to be attracted to the anode, and cations to the cathode. This creates the conditions for oxidation and reduction.
What is the function of the metallic pathway?
Allows the electrons generated at the anode to move to the cathode.
How does NACE define the role of the inspector?
A Quality Control Technician, primarily responsible for observing and reporting on coating application projects, and the degree of conformity the contractor is able to achieve.
What is the inspectors role when it comes to safety?
Enforcement of safety rules is not the responsibility of the inspector, but the inspector is required to know and obey safety requirements.
Name some tests that may need to be conducted during surface preparation of coating operations.
Atmospheric, equipment and mixing processes should be noted.
Name some of documents and reports that may be required to be maintained on a coatings project.
Materials inventory reports (detailing the types and quantities of all on-hand materials, batch numbers, and delivery and usage dates) Instrument calibration reports Daily and weekly reports Inspection log to provide a clearer view of all inspection activity
What are the most important characteristics of a good report?
Consistent with client expectations
Regular and accurate
Objective and professional
What is the inspectors primary responsibility, and what should the inspector not do as it pertains to the specification?
Be a useful team member Observe and document Not do: supervise and direct the operations
What type of information should you expect on a product data sheet?
Answers product questions.
What kind of information should you expect to find on the Material Safety Data Sheet?
The MSDS provides data on all the known substances within a product: Toxicity Health effects First aid Reactivity with other substances Proper disposal PPE requirements Spill handling
Explain the difference between Quality Control and Quality Assurance.
Quality control: control the quality of a product during production Quality Assurance: assures that a product is not defective after production
Types of soluble salt contamination include:
Chlorides, suflates and nitrates. (Soluble salts are not very soluble, and cannot be removed with a simple wash.)
If inspection is to be effective with regards to salts, the specification must clearly state:
Acceptable limits of soluble salts, The specific salts to be limited on the substrate, the specific test methods to use, the exact testing frequency, precisely where to administer the tests
tests for soluble salts include:
potassium ferricynide testing bresle patch testing sleeve testing
depth of surface profile can be evaluated by several methods:
ISO Comparators - works like a paint color patch Replica tape - a foam tape that is crushed against the blasted surface Digital profile gauge - measures peak to valley distances
The ISO comparator grades may be recorded:
Finer than fine - fine - medium - coarse - coarser than coarse
The two types of replica tape that are commonly used:
Replica tape measures the surface profile after blasting. The two most common types are coarse and extra coarse.
List the standards for using replica tape:
NACE Standard RP0287 and ASTM D4417 Method D
When using replica tape, common errors include:
Insufficient sampling, poor surface preparation, poor gauge accuracy, rubbing technique
Identify some of the defects that can be caused by incorrect application temperatures
Blistering, pin holing, cratering, dry spray, and Mud Cracking
Describe relative humidity
a comparison between the amount of actual airborne moisture, and the maximum possible moisture saturation within a given temperature range
what is the dew point temperature?
Dew point is the temperature at which the airborne moisture begins to return to a liquid state
Name some of the effects that wind can have on a coatings project.
blow abrasive blast debris into the coating application area, cause drift and overspray, uneven evaporation of solvents after application, and contribute to dry spray.
What are some of the common errors when using and electronic hygrometer?
taking readings in direct sunlight, leaving the instrument in place too long, removing the instrument before the readings stabilize
explain how to use a sling psychrometer
insert into a specialized wet sock, whirl the instrument for 40 seconds, read the wet bulb temperature, repeat until rhe wet bulb temperature remains the same from reading to reading, compare this reading to the dry bulb reading
Faying surfaces
Surfaces joined to create a friction grip
Gouges
Sharp indentations in the coating
Inclusions
A non metallic phase in a metal
Organic solvents
Solvents such as kerosene, turpentine, xylol, etc., that clean the metal by dissolving and diluting the grease contamination on the surface.
Surface cleanliness should be inspected (at a minimum) during these three junctures:
Before surface preparation begins
after surface preparation is comlete, and before any coating is applied
between each coating layer (in multi layer projects)
Factors in surface preparation that may affect service life include:
Oil and grease residue (prevents bonding with surface)
non-visible chemical salts residue (can create corrosion)
Rust on surface (adhesion failures)
Common design defects include:
Hard to reach or innaccesible areas
Rivets, bolts, other connectors
Welds
Gaps
Overlapping surfaces
Angle iron that is badly oriented or in complex arrangements
Threaded areas
Dissimilar metals
Sharp edges, corners, rough cut plate
Construction aids
Common fabrication defects include:
poor lamination
imperfect welds - weld spatter, skip welds, rough welds
gouges
sharp corners and edges
sharp bends or angles
Four typical SSPC-SP1 precleaning methods include:
Solvent wipe with cloth
immersion of the substrate in solvent
solvent spray
vapor degreasing
steam cleaning
emulsion cleaning
chemical paint stripping
alkaline cleaners
One standard to use with power tool cleaning is:
SSPC-SP 3
Four examples of power tools used for cleaning are:
rotary wire brush
Impact tools, such as chipping or scaling hammers (can damage the surface)
needle scaler (needle guns)
Rotary scalers
piston scalers
grinders and scalers
Disc sanders
vaccum connections
(Just need to know four)
Two abrasive blast methods are
Centrifugal blasting
sand injected water blast
slurry blast
dry grit blast (air blasting)
wet abrasive blast
Visual standards for abrasive blasting include
Visual SSPC-VIS 1
SSPC-SP10/NACE 2 limits staining to ? per each unit area.
5%
SSPC-SP 5/NACE 1 limits staing to ? per unit area.
none
SSPC-SP 6/NACE 3 limits staining to ? per each unit area.
33%
The two types of abrasive blasting nozzles include:
Venturi Nozzles
Straight Bore
Advantages of cenrifugal blast equipment include:
lower production costs
automated
very high rates of cleaning
The two broad classifications of curing mechanisms are
Nonconvertible and convertible
nonconvertible coatings cure by evaporating the solvent, and can be redissolved in the original solvent
Convertible coatings cure by polymerization. They are “convertible” because they convert into a new substance when they cure
List two nonconvertible coating types
Vinyl
Chlorinated rubber
List three convertible coating curing mechanisms
Oxidation - react with ozygen after the somvent evaporates
Co-Reaction - occurs when various compounds react to one another (and must be mixed)
Hydration - require some amount of water to cure
Fusion - forced heat curing
List two characteristics of oxidation cure coatings
Cannot be submerged
susceptible to excessive film build up
list three coating types that cure by polymerization
Epoxies
Polyurithanes
Polyureas
What is “induction time?”
the period of time after mixing, but before the coating can be applied
What is the main requirement for a hydration coating to cure?
water must be present
Industrial and marine coatings are commonly referred to by:
Adhesion Failures may be caused by:
Coating applied to a contaminated surface
Improperly prepared surface
Insufficient surface profile
Application of incompatible coatings
Checking can be described as:
Line cracks in the topcoat
non-drying films (failure to cure) may be caused by:
not adding cure to the base
adding the wrong cure
not adding the correct amount of cure during mixing
Some of the problems that can be caused by amine blush are:
surface tackiness
incomplete cure
poor adhesion
coating discoloration
(amine blush is caused by environmental conditions, such as rapid drops in temperature, cold weather or high humidity.)
Runs, sags and wrinkles may be caused by:
applying the coating too thickly
improper use of thinner
applying on a surface that is too hot
A powdery layer on the surface of a coating that is most common with epoxy coatings is:
Chalking
(caused by environmental radiation)
Cratering may be caused by:
Improper mixing can leave air bubble inclusions in the coating
vacuoles or voids are typically caused by:
mixers being run too fast
(vacuoles are caused by air bubbles in the coating. If theyburst, they are craters.)
Pinholes are:
Very small holes that appear in the coating
(caused by air or solvent escaping)
A common cause of blistering:
Some kind of contaminant, like
oil
moisture
grease
dirt
Cracking of a coating is noted:
by visual examination
Low temperature concerns during coating application include:
low temps may slow the curing process
High temperature concerns during coating application include:
solvents evaporating oo quickly
pot life of the coating may decrease
viscosity of two component materials may be affected
High humidity during coating application may:
Slow the evaporation rate of solvents, causing the coating to cure improperly
Coating may be applied using the following methods:
brush
roller
spray
airless spray
Goals of a pre job conference include:
Health and safety requirements
reporting requirements
responsibilities of the inspector
List three important properties of a coating:
Water resistance
ease of application
cohesive strength
Two broad coating classifications of a coating are:
Either
organic and inorganic
or
Convertible and nonconvertible
What are two primary components of a liquid applied coating?
Binders and solvents
(binders provide the functional properties of a coating. Some examples of binders are epoxy, polyurithane, alkyd, and acrylic. Solvents are used to liquify the binders. Other important components of liquid coatings are pigments and additives.)
Describe three methods by which a coating provides corrosion controll:
Barrier resisitance
inhibition: can prevent corrosion cells from forming, even if they do not completely prevent all contact with the environment
Sacrificial Anode
What are the three different ways a coating can adhere to the surface?
Chemical
mechanical
polar
(The most effective method is chemical bond, like galvanizing molten zinc to the surface. This melts the surface of the steel, making the coating a functional part of the surface.)
Non drying films (failure to cure) could be caused by:
The cure: not adding to the BASE IN THE FIRST PLACE, ADDING THE WRONG CURE, OR messing it up
The manufacturer may have sent the wrong cure
environmental factors: excessive humidity. Extreme temperatures can affect curing
Incorrect or contaminated thinner
General types of holiday detectors include:
High or low voltage DC detectors
high voltage pulsed DC
High voltage AC detectors
Low voltage (wet sponge) holiday detectors are powered by a battery with output voltages ranging:
5v-120v DC
Describe the low voltage (wet sponge) holiday detectors
non-conductive handle
electrified sponge
ground cable
High-voltage DC holiday detector types include:
Pulse type DC detectors
Constant Current detectors
Describe high voltage holiday detectors
portable
hand held
attached electrode (may resemble a steel brush or a spring coil that wraps around a pipline
The type of high voltage holiday detector that is used for concrete is:
High voltage Pulse-type DC detectors
What is a standard?
an industry guide that helps to establish norms and standardization within the industry
tends to cover:
- technical criteria
- methods
What percentage of NACE standards relate to coatings?
about 50% of NACE International standards are related to protective coatings
The inspectors checklist for surface preparation should include
ambient conditions
condition of substrate
fabrication defects
preblast surface cleanliness
shot/grit selection
shot/grit cleanliness
equipment
surface profile
surface cleanliness after blasting
operator qualifications
safety
Abrasive media types include:
cast steel
(removes scaleand other hard surface deposits)
steel grit
(irregular shapes, cuts away surface deposits and imperfections. Expensive)
Steel shot
(balls of steel, can drive impurities into the surface)
Crushed Slag
(fast cutting)
Ceramic Grit
(Expensive, very good cutting)
Silica Sand
(Cheap, can leave dust)
Garnet
Agricultural abrasives
Speciality abrasives
(Dry Ice, Ice, Plastic Beads, baking soda, Sponge)
List the pressure ranges that catagorize Low pressure water cleaning:
below 5000 psi
(this is considered a “rinse”)
List the pressure ranges that catagorize High pressure Water cleaning:
Not used very often.
5,000 - 10,000 psi
What are the pressure ranges for High-pressure waterjetting?
10,000 - 30,000 psi
What are the pressure ranges for Ultrahigh-pressure waterjetting?
Pressures above 30,000 psi
Three types of waterblasting include:
Grit blasting with a shroud
sand injected water blast
slurry blast with grit / water mix
The NACE - SSPC waterjetting standard is:
NACE - VIS 4
Three test methods for surface profile include:
comparator and coupons
Replica tape
dial gauge micrometer
Inspectors checklist summary
inspect equipment and materials to be used
pre-inspect the substrate
inspect during and after pre-cleaning process
perform specified tests to refrenced standards
accept or reject prepared substrate
inspect and accept prepared substrate
document the process
surface lamination
the most common surface defect on steel surfaces
caused by rolling the steel
