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AMPP CCI-2 practice questions

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Question 1Coating Inspection Fundamentals and Surface Preparation

Which abrasive blast cleaning standard is described as 'Near-White Metal' and requires a very thorough cleaning of the surface?

  1. SSPC-SP 6 / NACE No. 3
  2. SSPC-SP 7 / NACE No. 4
  3. SSPC-SP 10 / NACE No. 2 Correct answer.
  4. SSPC-SP 5 / NACE No. 1

Explanation

SSPC-SP 10 / NACE No. 2 defines Near-White Blast Cleaning, which leaves only very light staining permitted over no more than 5% of each unit area. White metal (SP 5) is the most thorough grade, while commercial (SP 6) and brush-off (SP 7) are progressively less thorough.

Question 2Coating Inspection Fundamentals and Surface Preparation

A coating inspector observes a surface with tightly adherent mill scale remaining after blast cleaning. This condition is most directly a concern because mill scale:

  1. reacts chemically with most epoxy primers to form a weak bond
  2. absorbs moisture and swells, lifting the coating film
  3. is cathodic to steel and can promote localized corrosion at breaks Correct answer.
  4. increases the surface profile depth beyond specification

Explanation

Mill scale is cathodic relative to the underlying steel, so at any discontinuity a galvanic couple forms and the small steel anode corrodes preferentially. This can undercut and disbond the coating. Mill scale must be removed to the degree required by the specified cleanliness standard.

Question 3Coating Inspection Fundamentals and Surface Preparation

The primary purpose of establishing an anchor profile before applying a protective coating is to:

  1. increase the electrical conductivity of the substrate
  2. provide mechanical keying that improves coating adhesion Correct answer.
  3. neutralize residual acid contamination
  4. seal the steel surface against moisture ingress

Explanation

An angular anchor profile provides mechanical interlock between the coating and the substrate, improving adhesion and helping resist underfilm migration. Profile depth must be matched to the coating's specified range; too little reduces adhesion and too much can cause thin spots over peaks.

Question 4Coating Inspection Fundamentals and Surface Preparation

An inspector measures surface profile using replica tape and obtains readings of 1.8, 2.0, 2.2, and 2.4 mils. The specification requires 1.5 to 3.0 mils. What is the correct inspection conclusion?

  1. The profile is unacceptable because the average is below 2.5 mils
  2. The profile is out of specification because readings vary too widely
  3. The readings are invalid because replica tape cannot measure below 2 mils
  4. The profile is acceptable because all readings fall within the specified range Correct answer.

Explanation

When every reading falls within the specified minimum and maximum, the profile is acceptable; normal variation is expected and is not itself a rejection criterion. Replica tape is a recognized field method for measuring profile across a wide range of depths.

Question 5Coating Inspection Fundamentals and Surface Preparation

Which surface preparation method is typically specified for a maintenance coating over tightly adherent existing coatings where full removal is impractical?

  1. Acid pickling of the entire surface
  2. Water jetting to a defined flash rust standard
  3. Abrasive blast cleaning to white metal
  4. Hand and power tool cleaning to remove loose material Correct answer.

Explanation

Hand and power tool cleaning (SSPC-SP 2 and SP 3) removes loose rust, loose coating, and other poorly adherent material, leaving tightly adherent material in place. This is commonly used in maintenance where full removal is impractical.

Question 6Coating Inspection Fundamentals and Surface Preparation

Soluble salts remaining on a blast-cleaned surface are a concern primarily because they:

  1. act as a lubricant between the coating and steel
  2. attract moisture osmotically and promote blistering and underfilm corrosion Correct answer.
  3. increase coating cure speed at elevated temperature
  4. reduce the anchor profile created by the abrasive

Explanation

Soluble salts such as chlorides and sulfates draw moisture through the coating film by osmosis, leading to blistering, disbondment, and accelerated corrosion at the interface. They must be removed and verified by conductivity testing before coating.

Question 7Coating Inspection Fundamentals and Surface Preparation

When using the Bresle method to test for soluble salts, the measured conductivity of the extraction solution is used to:

  1. measure the coating dry film thickness
  2. confirm the abrasive blast grade achieved
  3. estimate the concentration of soluble salts per unit area Correct answer.
  4. determine the surface profile depth

Explanation

The Bresle method extracts soluble salts from a defined area into a known volume of solution, and conductivity is correlated to salt concentration, expressed per unit area. It is a quantitative field method for contamination assessment.

Question 8Coating Inspection Fundamentals and Surface Preparation

An inspector finds visible oil and grease on a steel surface scheduled for blasting. What is the correct sequence of actions?

  1. Blast at higher pressure to burn off the contamination
  2. Apply coating and monitor for disbondment
  3. Blast first, then wipe the surface with solvent
  4. Clean the contamination first, then blast clean Correct answer.

Explanation

Oil and grease must be removed before blast cleaning, typically with solvent or detergent cleaning, because blasting can smear and drive contamination into the surface. Blast cleaning after degreasing removes residues and provides the required profile.

Question 9Coating Inspection Fundamentals and Surface Preparation

Which of the following best describes the condition known as 'flash rusting' after wet surface preparation?

  1. Rust that forms under an applied coating film
  2. Rapid light rusting of a cleaned steel surface before coating Correct answer.
  3. Deep pitting caused by acid residues
  4. Rust forming only at welds due to galvanic action

Explanation

Flash rust is the rapid formation of light rust on a freshly cleaned, bare steel surface, often after wet methods such as water jetting. Standards distinguish light, moderate, and heavy flash rust, and the specification defines how much is permissible before coating.

Question 10Coating Inspection Fundamentals and Surface Preparation

A specification requires SSPC-SP 10 / NACE No. 2 cleanliness. Which statement correctly distinguishes this from SSPC-SP 5 / NACE No. 1?

  1. SP 10 is only applicable to stainless steel
  2. SP 10 requires a deeper profile than SP 5
  3. SP 5 allows more staining than SP 10
  4. SP 10 permits light staining on up to 5% of each unit area, while SP 5 permits no visible residue Correct answer.

Explanation

Near-White (SP 10) permits very light staining, limited to no more than 5% of each unit area, whereas White Metal (SP 5) requires a surface free of all visible residue. Both are blast cleaning grades and do not by themselves set profile depth.

Question 11Coating Inspection Fundamentals and Surface Preparation

Which instrument is commonly used to measure surface profile by pressing a fine-pointed probe against the prepared surface?

  1. Depth micrometer with a pointed anvil Correct answer.
  2. Wet film comb
  3. Surface comparator disc
  4. Spring micrometer

Explanation

A depth micrometer fitted with a pointed anvil measures the distance between profile peaks and valleys on the prepared surface. Replica tape and comparator discs are alternative methods for assessing profile.

Question 12Coating Inspection Fundamentals and Surface Preparation

The main reason abrasive blasting is preferred over hand tool cleaning for immersion service is that abrasive blasting:

  1. removes all surface contamination and creates a uniform anchor profile Correct answer.
  2. produces a smoother surface that sheds water
  3. is faster and therefore cheaper in all cases
  4. eliminates the need for soluble salt testing

Explanation

Immersion service demands a high-integrity surface, and abrasive blasting both removes mill scale, rust, and old coating and produces a uniform angular profile for adhesion. Hand tool cleaning cannot achieve the same cleanliness or profile.

Question 13Coating Inspection Fundamentals and Surface Preparation

A coating is specified over a surface with a profile that is too deep for the specified film thickness. The most likely consequence is:

  1. increased cure rate of the coating
  2. improved flexibility of the coating film
  3. reduced adhesion due to lack of mechanical keying
  4. coating peaks exposed above the valleys with insufficient film over profile crests Correct answer.

Explanation

When profile depth is large relative to the coating thickness, the coating may not fully cover profile peaks, leaving thin spots that can corrode or fail prematurely. Profile and film thickness must be matched to ensure continuous coverage.

Question 14Coating Inspection Fundamentals and Surface Preparation

Which of the following is the correct description of the ISO 8501-1 visual assessment standards?

  1. They set abrasive size distribution requirements
  2. They define soluble salt limits by conductivity
  3. They specify coating dry film thickness tolerances
  4. They provide photographic reference standards for rust grades and preparation grades Correct answer.

Explanation

ISO 8501-1 provides photographic reference standards used to assess initial rust grades and the degree of surface preparation achieved, such as Sa 2½ and St 3. It is a visual comparison standard, not a numerical measurement method.

Question 15Coating Inspection Fundamentals and Surface Preparation

During inspection of a water-jetted surface, the specification permits 'light flash rust' but the surface shows reddish-brown rust that can be removed by wiping. This condition is best classified as:

  1. heavy flash rust
  2. light flash rust
  3. no flash rust
  4. moderate flash rust Correct answer.

Explanation

Moderate flash rust appears as a distinct reddish-brown layer that can be removed by wiping or light abrasion, whereas light flash rust is a faint discoloration that does not obscure the surface. Heavy flash rust is dense and does not wipe off easily.

Question 16Coating Inspection Fundamentals and Surface Preparation

Which of the following best explains why abrasive blasting abrasives should be free of chlorides and other soluble contaminants?

  1. Contaminants reduce the hardness of the abrasive
  2. Contaminants increase the anchor profile beyond specification
  3. Contaminants can be deposited on the substrate and cause coating failure Correct answer.
  4. Contaminants make the abrasive too heavy to project

Explanation

Abrasives that carry soluble salts can deposit them onto the freshly cleaned surface, creating a contamination layer that promotes osmotic blistering and corrosion. Abrasive cleanliness is therefore part of surface preparation quality control.

Question 17Coating Inspection Fundamentals and Surface Preparation

A steel surface is prepared to SSPC-SP 6 / NACE No. 3. Which statement describes the acceptable condition?

  1. A surface with loose rust and loose coating removed but staining permitted
  2. A surface with tightly adherent coating and rust removed, with staining permitted over more than 5% of the area Correct answer.
  3. A surface that has been solvent cleaned only
  4. A surface free of all visible residue

Explanation

Commercial Blast Cleaning (SP 6) permits staining over more than 5% of each unit area, provided it is tightly adherent and not loose. Near-White (SP 10) restricts staining to 5% or less, and White Metal (SP 5) permits none.

Question 18Coating Inspection Fundamentals and Surface Preparation

The primary function of a surface comparator disc during abrasive blast inspection is to:

  1. confirm the coating cure stage
  2. provide a visual reference for blast cleanliness or profile Correct answer.
  3. verify the conductivity of the extraction solution
  4. measure the depth of surface profile in micrometers

Explanation

Comparator discs are visual reference tools used to compare the prepared surface against known standards for blast grade or profile. They are aids to visual assessment, not measuring instruments.

Question 19Coating Inspection Fundamentals and Surface Preparation

An inspector is preparing to apply a coating over a surface that was blasted several days earlier and has since been exposed to humid air. Which concern is most relevant?

  1. The steel may have lost its original mill scale
  2. The coating may cure too quickly
  3. The surface may have developed rust or contamination and require re-preparation Correct answer.
  4. The abrasive may have changed size

Explanation

A blasted surface is highly reactive, and exposure to humid air can produce rust or contamination that compromises adhesion. The surface should be inspected and, if needed, re-prepared before coating.

Question 20Coating Inspection Fundamentals and Surface Preparation

Which of the following best describes the difference between a solvent wipe and detergent cleaning for surface preparation?

  1. Solvent wipe creates an anchor profile
  2. Detergent cleaning is only used after coating application
  3. Solvent wipe dissolves oils, while detergent cleaning can remove salts and other water-soluble contaminants Correct answer.
  4. Detergent cleaning removes mill scale, while solvent wipe removes rust

Explanation

Solvent cleaning (SSPC-SP 1) removes oil, grease, and similar organic contamination, while detergent or water-based cleaning can also remove water-soluble salts and other deposits. Both are cleaning methods and neither creates profile.

Question 21Coating Inspection Fundamentals and Surface Preparation

A specification calls for 'Sa 2½' under ISO 8501-1. This corresponds most closely to which SSPC blast grade?

  1. SSPC-SP 7
  2. SSPC-SP 10 Correct answer.
  3. SSPC-SP 6
  4. SSPC-SP 5

Explanation

ISO 8501-1 Sa 2½ is 'very thorough blast cleaning' and is generally aligned with SSPC-SP 10 / NACE No. 2 Near-White. Sa 3 aligns with White Metal (SP 5), and Sa 2 aligns with Commercial (SP 6).

Question 22Coating Inspection Fundamentals and Surface Preparation

Which factor most strongly influences the surface profile depth produced by abrasive blasting?

  1. The coating's pot life
  2. The color of the abrasive
  3. The size, shape, and hardness of the abrasive and the blast energy Correct answer.
  4. The ambient relative humidity

Explanation

Profile depth is governed by abrasive particle size, angularity, hardness, and the energy delivered by the blast equipment. Finer or rounded abrasives generally produce shallower profiles than coarse angular media.

Question 23Coating Inspection Fundamentals and Surface Preparation

An inspector finds that a prepared surface meets the required blast grade but shows a shiny, smeared appearance in some areas. The most likely cause is:

  1. insufficient blast pressure
  2. excessive abrasive size
  3. over-blasting with fine abrasive or a worn abrasive that polishes rather than cuts Correct answer.
  4. contamination with soluble salts

Explanation

A shiny, smeared appearance often indicates that the surface was polished or burnished rather than cut, which can occur with excessive fine abrasive or a worn abrasive. This condition can reduce the effective anchor pattern and should be investigated.

Question 24Coating Inspection Fundamentals and Surface Preparation

Which of the following is an appropriate use of a visual comparator for surface preparation?

  1. Checking the cure of a solvent-based coating
  2. Comparing the prepared surface to reference photographs for blast grade Correct answer.
  3. Measuring wet film thickness during application
  4. Determining the exact chloride concentration on the surface

Explanation

Visual comparators, such as ISO 8501-1 photographs or SSPC-VIS 1, are used to judge blast cleanliness grade by comparison. They do not quantify contamination or measure film properties.

Question 25Coating Inspection Fundamentals and Surface Preparation

A coating specification requires that all welds be inspected for surface defects before coating. Which weld condition is most likely to cause premature coating failure if not corrected?

  1. A sharp weld spatter or undercut that creates a void or stress riser Correct answer.
  2. A weld that is slightly wider than adjacent plate
  3. A smooth, convex weld bead
  4. A weld with a slight uniform color change

Explanation

Weld spatter, undercut, and sharp edges create voids, stress risers, and hard-to-coat areas where the film may be thin or discontinuous, leading to premature failure. These defects should be ground or repaired before coating.

Question 26Coating Inspection Fundamentals and Surface Preparation

Which surface preparation method is defined by SSPC-SP 1?

  1. Power tool cleaning
  2. Solvent cleaning Correct answer.
  3. Abrasive blasting
  4. Hand tool cleaning

Explanation

SSPC-SP 1 covers solvent cleaning, which is used to remove oil, grease, soil, and other soluble contaminants. Hand tool cleaning is SSPC-SP 2, power tool cleaning is SSPC-SP 3, and abrasive blasting is covered by SSPC-SP 5, SP 6, SP 7, or SP 10 depending on the degree.

Question 27Coating Inspection Fundamentals and Surface Preparation

What is the primary purpose of abrasive blasting in surface preparation?

  1. To remove mill scale, rust, and old coatings and to create a profile Correct answer.
  2. To smooth the surface for better adhesion
  3. To apply a protective coating layer
  4. To clean the surface with solvents

Explanation

Abrasive blasting uses propelled abrasive particles to remove surface contaminants and to roughen the surface, creating a profile that enhances coating adhesion. It does not apply coating, use solvents, or smooth the surface.

Question 28Coating Inspection Fundamentals and Surface Preparation

Which of the following is a common visual standard used to assess the cleanliness of blast-cleaned steel surfaces?

  1. ASTM D3359
  2. ISO 8501-1 Correct answer.
  3. ISO 9001
  4. SSPC-PA 2

Explanation

ISO 8501-1 provides visual assessment of surface cleanliness by comparing the prepared surface to photographic reference standards. ISO 9001 is a quality management standard, ASTM D3359 covers adhesion testing, and SSPC-PA 2 covers dry film thickness measurement.

Question 29Coating Inspection Fundamentals and Surface Preparation

What does the term 'surface profile' refer to in coating inspection?

  1. The color of the prepared surface
  2. The angle of the surface relative to horizontal
  3. The thickness of the applied coating
  4. The roughness or anchor pattern of the prepared surface Correct answer.

Explanation

Surface profile describes the microscopic roughness created by surface preparation, which provides a mechanical key for coating adhesion. It is not related to coating thickness, surface angle, or color.

Question 30Coating Inspection Fundamentals and Surface Preparation

Which of the following is a consequence of applying a coating over a surface that has been contaminated with oil and grease?

  1. Increased coating thickness
  2. Improved adhesion due to lubrication
  3. Faster curing of the coating
  4. Poor adhesion and possible coating failure Correct answer.

Explanation

Oil and grease prevent the coating from properly bonding to the substrate, leading to poor adhesion, blistering, or delamination. They do not improve adhesion, accelerate curing, or increase thickness.

Question 31Coating Inspection Fundamentals and Surface Preparation

What is the purpose of a surface comparator in coating inspection?

  1. To determine the surface temperature
  2. To estimate the surface profile by visual and tactile comparison Correct answer.
  3. To measure the coating thickness
  4. To test the adhesion of the coating

Explanation

A surface comparator is a reference standard used to visually and tactilely compare the prepared surface profile to known roughness levels. It is not used for thickness, adhesion, or temperature measurement.

Question 32Coating Inspection Fundamentals and Surface Preparation

Which of the following is a typical method for measuring surface profile?

  1. Using a hygrometer
  2. Using a wet film thickness gauge
  3. Using a profile gauge or replica tape Correct answer.
  4. Using a conductivity meter

Explanation

Surface profile can be measured by instruments such as profile gauges, replica tape, or stylus instruments. Wet film thickness gauges measure coating thickness, hygrometers measure humidity, and conductivity meters measure soluble salts.

Question 33Coating Inspection Fundamentals and Surface Preparation

What is the correct action if a prepared surface is found to have visible rust before coating application?

  1. Proceed with coating as rust improves adhesion
  2. Apply the coating over the rust to save time
  3. Re-clean the surface to remove rust before applying the coating Correct answer.
  4. Ignore the rust if it is light

Explanation

Rust indicates that the surface is not properly prepared and will interfere with coating adhesion. The surface must be re-cleaned to the specified standard before coating. Applying coating over rust or ignoring it can lead to premature failure.

Question 34Coating Inspection Fundamentals and Surface Preparation

Which of the following best describes the purpose of SSPC-SP 6 / NACE No. 3?

  1. White metal blast cleaning
  2. Near-white blast cleaning
  3. Brush-off blast cleaning
  4. Commercial blast cleaning Correct answer.

Explanation

SSPC-SP 6 / NACE No. 3 defines commercial blast cleaning, which removes all visible oil, grease, dirt, mill scale, rust, coating, and other foreign matter, leaving staining as allowed. White metal is SP 5, brush-off is SP 7, and near-white is SP 10.

Question 35Coating Inspection Fundamentals and Surface Preparation

What does the term 'anchor pattern' refer to in surface preparation?

  1. The method of applying the coating
  2. The roughness profile that enhances coating adhesion Correct answer.
  3. The pattern of the abrasive blast nozzle
  4. The pattern of rust on the surface

Explanation

Anchor pattern is another term for surface profile, which is the roughness created by abrasive blasting that provides a mechanical key for the coating. It is not related to rust patterns, application methods, or nozzle patterns.

Question 36Coating Inspection Fundamentals and Surface Preparation

Which of the following is a potential consequence of using an abrasive that is too coarse?

  1. Insufficient surface profile
  2. Inadequate cleaning of the surface
  3. Increased coating adhesion
  4. A surface profile that is too deep for the coating thickness Correct answer.

Explanation

Coarse abrasives create a deeper profile, which may not be adequately covered by the specified coating thickness, leading to potential peaks exposed and early corrosion. Finer abrasives are used to achieve a shallower profile. Too coarse abrasive does not cause insufficient profile or inadequate cleaning; it may improve adhesion but not excessively.

Question 37Coating Inspection Fundamentals and Surface Preparation

What is the primary function of a blast nozzle in abrasive blasting?

  1. To measure the abrasive flow rate
  2. To filter the abrasive
  3. To direct and accelerate the abrasive particles toward the surface Correct answer.
  4. To mix the abrasive with air

Explanation

The blast nozzle shapes and accelerates the stream of abrasive particles to impact the surface for cleaning and profiling. It does not mix (that happens in the blast pot or mixing valve), filter, or measure flow.

Question 38Coating Inspection Fundamentals and Surface Preparation

Which of the following is a sign that a surface has been over-blasted?

  1. Presence of mill scale
  2. Uniform gray color
  3. Excessive surface profile and possible damage to the steel substrate Correct answer.
  4. A smooth, polished surface

Explanation

Over-blasting can create a profile that is too deep, embed abrasives, or even remove excessive base metal, which can be detrimental to coating performance. A smooth surface indicates insufficient blasting, mill scale indicates incomplete cleaning, and uniform gray is a normal appearance after blasting.

Question 39Coating Inspection Fundamentals and Surface Preparation

What is the purpose of conducting a solvent wipe test on a prepared surface?

  1. To measure surface profile
  2. To determine surface temperature
  3. To detect the presence of oil and grease Correct answer.
  4. To assess coating adhesion

Explanation

A solvent wipe test involves wiping the surface with a solvent and examining the wipe for discoloration, which indicates oil or grease contamination. It is not used for profile, temperature, or adhesion measurement.

Question 40Coating Inspection Fundamentals and Surface Preparation

Which of the following is the correct description of ISO 8501-1 Sa 2?

  1. Light blast cleaning
  2. White metal blast cleaning
  3. Thorough blast cleaning Correct answer.
  4. Very thorough blast cleaning

Explanation

ISO 8501-1 Sa 2 denotes thorough blast cleaning, where rust, mill scale, and coatings are removed but slight staining is allowed. Sa 1 is light, Sa 2½ is very thorough, and Sa 3 is white metal.

Question 41Coating Inspection Fundamentals and Surface Preparation

What is the primary reason for specifying a surface profile depth range in a coating specification?

  1. To ensure the profile is sufficient for adhesion without exceeding the coating's ability to cover it Correct answer.
  2. To reduce the amount of abrasive used
  3. To make the surface look uniform
  4. To speed up the coating application

Explanation

The profile must be deep enough to provide mechanical adhesion but not so deep that the coating cannot cover the peaks, which could lead to premature corrosion. The range is not for appearance, abrasive savings, or application speed.

Question 42Coating Inspection Fundamentals and Surface Preparation

Which of the following is a characteristic of a properly prepared surface according to SSPC-SP 10 / NACE No. 2?

  1. White metal with no staining
  2. Commercial blast with up to 33% staining
  3. Near-white metal with no more than 5% staining Correct answer.
  4. Brush-off blast with no removal of tightly adherent matter

Explanation

SSPC-SP 10 / NACE No. 2 requires near-white metal cleanliness, allowing slight staining on no more than 5% of the surface. White metal is SP 5, commercial is SP 6, and brush-off is SP 7.

Question 43Coating Inspection Fundamentals and Surface Preparation

What is the correct procedure for measuring surface profile using replica tape?

  1. Press the tape against the surface, burnish it, and measure the impression with a micrometer Correct answer.
  2. Use the tape to pull off the coating and measure adhesion
  3. Spray the tape with a developer and compare to a color chart
  4. Place the tape on the surface and read the color change

Explanation

Replica tape (such as Testex) is pressed against the blasted surface and burnished, causing the tape's compressible foam to conform to the profile. The tape is then measured with a spring micrometer to determine the profile depth. It does not involve developers, color change, or adhesion testing.

Question 44Coating Inspection Fundamentals and Surface Preparation

Which of the following is a potential problem if the surface profile is too shallow?

  1. Increased risk of solvent entrapment
  2. Difficulty in measuring coating thickness
  3. Insufficient mechanical adhesion of the coating Correct answer.
  4. Excessive coating consumption

Explanation

A shallow profile provides less mechanical key for the coating, which can lead to poor adhesion and premature failure. Excessive coating consumption is more related to deep profile, and thickness measurement or solvent entrapment are not directly caused by shallow profile.

Question 45Coating Inspection Fundamentals and Surface Preparation

What does the term 'mill scale' refer to?

  1. A method of coating application
  2. A type of abrasive used in blasting
  3. A layer of iron oxides formed on steel during hot rolling Correct answer.
  4. A measurement of surface profile

Explanation

Mill scale is a tightly adherent oxide layer that forms on steel during hot rolling. It is cathodic to steel and can promote corrosion if not removed. It is not an abrasive, a profile measurement, or an application method.

Question 46Coating Inspection Fundamentals and Surface Preparation

Which of the following is a reason for conducting a blast cleaning inspection immediately after blasting?

  1. To check the weather forecast
  2. To let the abrasive settle
  3. To prevent recontamination and to ensure the surface is coated before rusting occurs Correct answer.
  4. To allow the surface to cool down

Explanation

Blast-cleaned steel is highly reactive and can flash rust quickly, especially in humid conditions. Inspection and coating should follow promptly to avoid recontamination. Cooling, abrasive settling, and weather checks are not the primary reasons.

Question 47Coating Inspection Fundamentals and Surface Preparation

What is the purpose of a 'blast pot' in abrasive blasting equipment?

  1. To filter the abrasive
  2. To compress air for the blast
  3. To measure the surface profile
  4. To hold and regulate the flow of abrasive to the blast nozzle Correct answer.

Explanation

The blast pot is a pressure vessel that holds abrasive and uses air pressure to feed it into the blast stream at a controlled rate. It does not compress air (that is the compressor), filter abrasive, or measure profile.

Question 48Coating Inspection Fundamentals and Surface Preparation

Which of the following best describes the difference between brush-off blast cleaning (SSPC-SP 7) and commercial blast cleaning (SSPC-SP 6)?

  1. Brush-off is a more thorough cleaning than commercial
  2. Brush-off and commercial are identical in cleanliness
  3. Brush-off allows tightly adherent mill scale and coatings to remain, while commercial removes all visible contaminants Correct answer.
  4. Brush-off removes all visible contaminants, while commercial allows some to remain

Explanation

SSPC-SP 7 (brush-off) is the least thorough blast cleaning, allowing tightly adherent mill scale, rust, and coatings to remain. SSPC-SP 6 (commercial) removes all visible oil, grease, dirt, mill scale, rust, coating, and foreign matter, leaving only staining. Thus, brush-off is less thorough than commercial.

Question 49Coating Inspection Fundamentals and Surface Preparation

An inspector observes a prepared surface that meets the cleanliness requirements of SSPC-SP 10 but has a profile of 2 mils (50 micrometers). The specified coating is a 5-mil (125 micrometers) DFT system. What is the most likely concern?

  1. The profile may be too deep for the coating thickness, leading to exposed peaks Correct answer.
  2. The coating will not cure properly
  3. The surface is too clean for the coating
  4. The profile is too shallow for adequate adhesion

Explanation

A 2-mil profile with a 5-mil coating may leave peaks insufficiently covered, increasing the risk of early rusting. The profile is actually quite deep; typical specifications might call for 1.5 to 2.5 mils for some coatings, but with only 5 mils DFT, the peaks could be exposed. The profile is not too shallow; cleanliness does not hinder coating; curing is not directly affected by profile.

Question 50Coating Inspection Fundamentals and Surface Preparation

Which of the following is a potential consequence of blasting with abrasive contaminated with soluble salts?

  1. Increasing the surface profile
  2. Reducing the need for a primer
  3. Embedding salts into the surface, leading to osmotic blistering Correct answer.
  4. Improving coating adhesion

Explanation

Soluble salts embedded in the surface can draw moisture through the coating, causing osmotic blistering and premature failure. Contaminated abrasive does not improve adhesion or reduce primer need, and its effect on profile is not the primary concern.