Abrasives Flashcards by Sara Sheppard

Shot/Grit:

Cast Steel is a hard 1___ abrasive used to remove scale and other 2___ ___ ___.

Metallic

2. Hard surface deposits.

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Shot/Grit:

Steel grit abrasives have 1___ shapes and are effective in cutting away surface deposits. Steel grit is 2 ___ and generally used only in 3___ ___ and when cheaper abrasives are unavailable. Because steel grit can be recycled, it reduces the overall waste stream.

Irregular
Expensive
Recycle Systems.

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Shot/Grit:

Steel shot is 1___; it can be produced accidentally as a byproduct, or intentionally for blast cleaning. Steel shot is good for 2___ ___ deposits. Because of it’s 1. ___ shape, it ricochets in enclosed areas and causes 3___ ___. Steel shot may 4___ light materials and drive mill scale and other materials into the surface.

Spherical.
Heavy Brittle
Multiple Impacts.
Stretch

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Shot/Grit

Cast iron is the 1___ metallic abrasive and is used to remove scale and other hard surface deposits. Harness should not be confused with 2___; hard abrasives sometimes have high breakdown rates due to their 3___. This product should not be used in 4___ environments; it has a high initial cost but can be recycled.

Hardest.
Toughness.
Brittleness
Corrosive Environments.

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Shot/Grit

Malleable iron is a relatively hard metallic abrasive used to remove scale and other hard deposits. True or False?

True.

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Shot/Grit are often ___ ___ to different hardnesses to increase their life and the rate of cleaning.

Heat Treated

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Hard abrasives (62-65 Hardness, Rockwell C) are often used for ___, but they break down rapidly.

Etching.

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Softer abrasives 35-43 Hardness Rockwell C, may be used for easier ___ ___.

Cleaning Jobs

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62-65 Hardness, Rockwell C Abrasives are considered?

Hard

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35-40 Hardness Rockwell C Abrasives are considered?

Soft.

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These abrasives may round up after use?

Soft abrasives. 35-40 HRC

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The average harness of metal abrasives is __-___ HRC which works well as an air blast abrasive.

45-50

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Crushed Slag is also knows as?

Refactory Slag.

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Crushed slag is manufactured from byproducts of ___ ___, ___ ___ and ___.

Burning Coal, Refining Copper and Nickel.

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Crushed Slag is a ___ ___ abrasive with ___ ___.

Fast Cutting abrasive with Medium Durability.

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SSPC-AB 1, (Mineral and Slag Abrasives) defines the requirements for selecting and evaluating ___ and ___ ___ which are used for blast cleaning steel and other surfaces.

Mineral and Slag

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SSPC-AB 1 (Mineral and Slag Abrasives) mainly covers abrasives intended for ___ ___ use without ___, reclaimed materials must be retested before reuse.

One time use without recycling.

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Ceramic grits are?

Aluminium Oxides and Silicon Carbides

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Aluminium Oxides and Silicon Carbides (Ceramic Grits) are relatively ___ abrasives but their use is sometimes justifiable because of their special properties.

Expensive.

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Aluminium Oxides and Silicon Carbides (Ceramic Grits):

Because the particles retain ___ ___ ___, their cutting action can be particularly effective, especially on hard-base materials which may resist effective blast cleaning by chilled cast iron grit.

Sharp cutting edges.

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Aluminium Oxides and Silicon Carbides (Ceramic Grits):

Their effective cutting action is achieved at ___ ___ than other abrasives normally require.

Air pressures.

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Ceramic Grits are particularly well suited to thin metal surfaces which ___ or ___ if blasted with chilled iron grit at conventional blast pressures.

Buckle or distort.

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Ceramic Grits (Aluminium Oxides and Silicon Carbides) are essentially inert to normal corrosive influences, they can be used to safely grit blast ____ or other ___ material surfaces without causing rust staining, discoloration, or bimetallic corrosion.

Stainless Steel or other nonferrous

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Silica sand is still used in the US because it is ?

Cheap

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The high breakdown rate of silica sand may tent to counter its original low cost and usually no attempt is made to ___ __. However, it is often considered (Particularly in the US.) to be the most economical abrasive used in industrial field applications.

Reclaim it

Sand-blasted surfaces may require a final ___ with ___ to remove dust remaining on the surface.

Cleaning with Air | Blow down.

Almandine Garnet is the 1___ and ___ of garnets and can withstand higher cutting speeds while maintaining low 2___ ___.

1. Heaviest and Hardest. | 2. Dust levels.

With a crystiline shape, fast cutting action, and longer life span ___ is a highly efficient and highly effective abrasive.

Garnet

In addition other abrasives discussed, use ___ ___ when the dust from another abrasive may harm sensitive equipment. An example is using crushed walnut shells to blast clean components of the space shuttle to preserve the integrity of the special alloys.

Agricultural Abrasives

When stainless steel or other high purity allows are blasted, it is important that the abrasive does not ___ ___ ___ in the surface.

Embed metallic particles.

Specialty abrasives include abrasives such as ___ ___, ___ ___, ___, ___ ___ and ___.

Dry Ice, Plastic Beads, Sponge, Soda Bicarbonate, and Ice.

Dry Ice is 1___ ___ frozen solid. It may be produced on site by cooling liquid 1___ ___ then compressing the resulting flakes into pellets, or by grinding and screening blocks of dry ice.

Carbon Dioxide

The boiling point of dry ice is ___ and it can cause frostbite if it comes into contact with exposed skin.

-110F

Use dry ice to remove certain types of surface contaminants and ___ ___ ___.

Existing Organic Coatings.

Dry ice does not ___ the surface roughness of metal surfaces and produces little to no dust. Usually leaving the substrate dry and cold.

Change

Dry ice is a 1___ ___ abrasive because it 2___ immediately after use.

1. Single Use | 2. Evaporates

Ice is frozen produced on, or off, site. The ice is ___ and ___ to produce the blast abrasive.

Crushed and Seived.

Ice removes certain types of surface contaminants and existing organic coatings. It does not change 1___ ___ or produce dust, but does the the substrate 2___.

1. Surface roughness. | 2. Wet.

Ice is a ___ ___ abrasive.

Single use.

Plastic Bead abrasives are small plastic beads about the size of the holes in a ___ ___.

Plastic Button

Plastic Bead abrasives remove coatings with ___ ___ ___ to the substrate.

Minimal Roughness change.

Plastic Beads are almost always used in ___ ___.

Recovery Systems.

Plastic Bead abrasives are used extensively to ___ ___ from ___.

Strip coatings from aircraft.

The dust from plastic bead abrasives may be ___.

Combustible.

Plastic Bead blasting operations require ___ ___ because the abrasive flow, work to nozzle distance, and blast air pressure are different for each coating type. These variables are usually determined by the blast operator.

Extensive Training

Plastic bead abrasives leave the surface dry, but it may be dusty. True or False?

True

Baking soda (Sodium Bicarbonate is usually used in a ___ ___ driven by compressed air and cannot be recycled.

Water Slurry

Sodium Bicarbonate removes surface contamination and existing coatings with 1___ substrate change. Although it produced little or no dust, 2___ the substrate as a final step. The operator requires special training.

1. Minimum. | 2. Rinse

Synthetic sponge particles remove surface contaminants and create a ___ ___ suitable for recoating.

Surface Profile

Compressed air propels the sponge particles to the surface where, upon impact, they 1___ and ___ the surface. The sponge particles clean the surface by 2___ contaminants and trapping them within the sponge particles. The result is a very clean surface with suitable abrasion to remove corrosion and provide an 3___ ___ for industrial coatings.

1. Expand and abrade. 2. Absorbing. 3. Anchor Profile

Sponge particles may be discarded after one use or used repeatedly to reduce waste and disposal needs. True or False?

True

Sponge blasting creates very little 1___, is extremely worker friendly, and can provide a variety of 2___ ___since abrasives may be encased within the sponge particles to achieve the desired results.

1. Dust. | 2. Anchor profiles.

Inspectors and operators should ensure that everyone follows the specified 1___ ___. Most 2. ___ ___ such as iron and steel shot/grit, and expensive abrasives such as glass beads, may be recycled. Make sure 3. ___ are removed from the abrasive materials if they are to be recycled.

1. Recycling Procedure. 2. Metallic Abrasives. 3. Contaminants.

Abrasives should be stored off the ___, away from moisture and the elements.

Ground

Each type of abrasive is generally available in ___ ___ ___ size.

More than ne

Abrasives are graded according to how fine a ___ or ___ ___ they can pass through without one particle of abrasive remaining.

Mesh or Sieve Screen

When in doubt about whether a given abrasive is the correct size, perform a ___ or ___ test.

Mesh or Sieve test.

Equipment required for the Mesh/Sieve test: 1. An accurate ___. 2. A set of US National Bureau of Standards (NBS) ___ 3. A convenient quantity of abrasive to ___. One Kilo is a good weight.

1. Balance. 2. Screens. 3. Weigh.

To perform a mesh/sieve test: 1. Pour the abrasive into the top of the ___ ___. 2. The screens should be nested so that the largest mesh is on ___ , and the smallest at the ___. 3. (I'm assuming something comes after this but the book ended there and moved on to another topic.)

1. Nested Screens. | 2. Largest at the top. Smallest at the bottom.

Test abrasives for cleanliness with the simple 1___ ___. 2. Drop come abrasive into a small vial of water with a known ___ and shake. 3. Typically the ratio should be ___ volume of abrasive to ___ volumes of water. 4. Inspect the top of the water for a film of ___ or oil. 5. Check the water for visible ____. 6. Use a ___ or ___ ___ test in the vial to tell whether the abrasive is acidic or alkaline. This will indicate the actual value of acidity (Blue to Red) or alkalinity.

1. Vial Test 2. Known pH (Preferably deionized/distilled water with a pH of 7.) 3. One volume of abrasive to two parts water. 4. Grease or oil. 5. Turbidity (Cloudiness due to sediment. which is a sign of excess dirt/dust/clay) 6. Litmus or pH paper.

Litmus and pH papers indicate the presence of chemical salts dissolved in water that form an acidic or basic solution. 1. If red paper changes to blue, the solution is? 2. If blue paper changes to red, the solution is? 3. If the paper does not change, the solution is?

1. Basic. 2. Acidic. 3. Neutral.

Litmus and pH papers will not detect the presence of?

Chlorides.

If the pH test indicates the solution is neutral, it does not indicate the absence of 1___ ___ ___ because some chemical salts, such as sodium chloride (Common Sea Salt) form a near-neutral solution. Specific test papers may indicate the presence of 1___ ___ ___.

1. Soluble Chemical Salts.

ASTM C 136 is the test method for?

Fine and coarse aggregates.

ASTM C 136 (Fine and coarse aggregates. ) Typically a 2 lb/1kg representative sample of abrasive is sieved through a series of screens and the percentage retained on each screen size is recorded. This test enables the inspector to compare the particle size and distribution of the abrasive with the data furnished by the abrasive supplier.

True

The peening action of shot abrasives can reduce incidents of ___ ___ ___.

Stress corrosion cracking.

ASTM C 136 Step Two: Shake the screens over the retaining pan, the abrasive particles remain on the screen whose hole size is ___ ___ than the abrasive particle. The finest abrasive particles pass all the way through and are caught on the pan.

1. Just Smaller.

ASTM C 136 Step 3: Weigh the particles that remain on each screen and calculate the percentage of retained. This is why 1,000 g of abrasive is so convenient. If 238g was retained at a given level, we know that is ___ ___of the abrasive without a lot of extensive arithmetic.

23.8 percent.

ASTM D 4285 is the?

Blotter Test.

Check compressed air for blast cleaning operations for the presence of water or oil by a simple ___ ___.

Blotter Test. ASTM D 4285

ASTM D 4285

(Standard Test Method for Indicating Oil or Water in Compressed Air)

ASTM D 4285 requires an 1___ paper, such as white absorbent paper, cloth on a rigid backing, or a non-absorbent collector (2___) made of transparent plastic. C Center the collector in the discharging air stream within 3___ if the discharge point for 4___ ___. Conduct the test on the discharging air as close to the use point as possible and after the 5___ ___ and ___ ___.

1. Absorbent 2. 1/4 in 3. 24 in 4. One Minute 5. Inline oil and water separators.

When conducting the blotter test (ASTM D 4285) the inspector should: 1. Allow the compressed Air system to reach ___ ___. 2. Allow air to discharge at ___ ___ to remove accumulated condensation in the system. 3. Fasten the collector material to a ___ ___ avoiding personal contact with the air stream.

1. Operating conditions. 2. Operating conditions. 3. Rigid Backing

According to ASTM D 4285, any indication of oil discoloration on the collector shall be cause for ___ of the air for use in any part of the coating process. Any indication of water shall be cause for rejection of the air in for use in those applications where water would be detrimental.

Rejection

To distinguish hydrocarbon oils from water, use a ___ ___ or detect the characteristic odor of oil. Also inspect the surface being cleaned for any sign of oil or water.

UV Light

Abrasives Flashcards

(75 cards)