Abrasive Blasting

Question 1

The most generally established method of surface prep for coating application is?

Answer 1

Dry grit blasting.

Question 2

Dry Grit Blasting uses a ___ ___ ___ of grit projected at a surface to remove rust, mill scale, or other contaminants and to create a rough surface good for adhesion.

Answer 2

Highly concentrated stream.

Question 3

When modern coatings are applied, there is no truly ___ or ___ equivalent alternative process.

Answer 3

Satisfactory or economically

Question 4

The fundamental principle of grit blasting is to remove ___, ___ ___ or other surface contaminants and to obtain a suitably roughened surface.

Answer 4

Rust, Mill Scale.

Question 5

Grit blasting is done by projecting a highly concentrated stream of relatively small abrasive particles, at ___ ___ against the surface to be cleaned.

Answer 5

High velocity.

Question 6

The high velocity impact of the abrasive particles ___ the ___.

Answer 6

Abrades the surface.

Question 7

Blast cleaning removes rust, mill scale, old coatings and some of the base metal. True or False?

Answer 7

True

Question 8

The most common method of surface prep is?

Answer 8

Abrasive blast cleaning.

Question 9

The abrasive is forces from the 1___ ___, under pressure, 2___ the ___ ___ and onto the 3___.

Answer 9

1. Blast Pot
2. Through the blast hose.
3. Substrate.

Question 10

Abrasive blasting is a high production method for ___ ___ jobs. i.e. in shipyards, refineries, buildings, etc.

Answer 10

Heavy duty

Question 11

Abrasive Blast Equipment: The Air compressor feeds both the air supply for the blaster and the Blast pot. True or False?

Answer 11

True

Question 12

The Air supply for the blaster will/may have both a ___ ___ ___ and a ___ ___.

Answer 12

Breathing air filter and a CO Monitor.

Question 13

There may/will be a ___ between the compressor and the Blast Pot.

Answer 13

Dryer

Question 14

The blast hose extents from the blast pot to the nozzle and may be intersected with a?

Answer 14

Blast Hose Coupling.

Question 15

The care, safety, and efficient use of the ___ ___ can save money in both man-hours and abrasives.

Answer 15

Blast Pot

Question 16

On-going maintenance for blast pots are needed to eliminate ___ and ___ ___.

Answer 16

Leaks and pressure loses.

Question 17

In most countries, the Vessel (Blast Pot) must be inspected annually and ___ ___ to one and a half times the design pressure to ensure save and effective functioning.

Answer 17

Hydro Tested

Question 18

Blast cleaning is a potentially ___ operation.

Answer 18

Hazardous

Question 19

With abrasives and equipment both under pressure, safety is very critical. True or False?

Answer 19

True

Question 20

Abrasives and air leave the nozzle at of close to ___ mph which is ___ ft/s or about half the speed of a shotgun blast.

Answer 20

450 mph which is 660 ft/s.

Question 21

At such high velocity, abrasives can strike surfaces or workers a considerable ___ from the operation.

Answer 21

Distance.

Question 22

Although blast hoses are ‘static dissipating, it is still essential to ____ the ___ ___. Including hoses, operator and work piece, to prevent injury due to electric shock.

Answer 22

Ground the entire system.

Question 23

Grounding is particularly important when the operator is 1___ at ___ or when blasting in a 2___ ___.

Answer 23

1. Working at heights.

2. Hazardous environment.

Question 24

The air supply hose carries air from the ___ to the abrasive blast unit (Blast/sand pot.)

Answer 24

Compressor

Question 25

Generally, the larger the air line, between the compressor and the blast pot, the better. No smaller than ___ inches internal diameter is recommended.

Answer 25

1.25 inches.

Question 26

The recommended air supply hose size is ___ to ___ times the nozzle orifice.

Answer 26

Three to four.

Question 27

On air supply lines longer than 1___ the hose ID (Inner Diameter) should be 2___ times the blast nozzle orifice size. The larger hose eliminates loss of air pressure due to 3___.

Answer 27

1. 100 ft 2. Four 3. Friction

Question 28

The Air Supply hose extends from the 1.___ to the 2.___ and then ends at the 3.___.

Answer 28

1. Compressor 2. Dryer 3. Blast Pot

Question 29

The blast hose extends from the ___ __ to the ___.

Answer 29

Blast Pot to the Nozzle.

Question 30

There are two types of abrasive supply hoses: 1. ___ __ 2. ___ ___.

Answer 30

1. Four-ply | 2. Two-ply

Question 31

__ ___ Blast Hoses should be used when the hose is subject to external abuse or when there is danger of the operator pulling at right angles.

Answer 31

Four Ply

Question 32

___ ___ Blast Hoses are lighter hoses some blasters prefer because of greater flexibility.

Answer 32

Two Ply

Question 33

The size and length of abrasive blast hoses are related to their?

Answer 33

Efficiency

Question 34

A blast hose ID should be ___ to ___ times the size of the nozzle orifice.

Answer 34

Three to four

Question 35

The 'Whip Length' is the ___ section of the blast hose.

Answer 35

Last

Question 36

The Whip gives the blaster better handling and enhances his ability to ___ the ___ ___ ___ ___.

Answer 36

Handle the hose under high pressure.

Question 37

The Whip is usually ___ to ___ ft long and has a smaller diameter than the rest of the blast hose.

Answer 37

10-15 ft.

Question 38

The smaller ID of the whip causes a ___ in ___ so it is recommended that operators use a whip attachment only when necessary.

Answer 38

Drop in pressure.

Question 39

Most blast hoses are now made with an internal 1___, loathing the hose rubber with 2___ ___ allows static electricity to drain to earth.

Answer 39

1. Ground. | 2. Carbon Black

Question 40

Use only ___ ___ to ensure operator safety.

Answer 40

Grounded hoses.

Question 41

Couplings connect the blast hose sections. Using only ___ ___ is highly recommended.

Answer 41

Fitted Couplings

Question 42

Internally fitted couplings reduce hose ID and 1___ ___ significantly. In addition, a turbulent condition may occur at the point where the air and abrasives hit the leading edge of the 2___ inside the hose resulting in 3 ___ ___ and heavy wear at that point.

Answer 42

1. Air capacity. 2. Nipple 3. Pressure drop.

Question 43

Couplings are held together by screws that penetrate into the wall of the hose. Ensure the screws do not penetrate the ___ causing air leaks and loss of pressure.

Answer 43

Hose.

Question 44

Because of inevitable pressure drops within air lines, keep pressure hoses as ___ as possible.

Answer 44

Short

Question 45

Preferably, the blast hose (From pot to nozzle) should not be more than ___ long.

Answer 45

20 ft

Question 46

If blast hose length, from pot to nozzle, is required to be more than 1___, keep the hose 2___, ensure that any 3___ are wide and have smooth radius.

Answer 46

1. 20 ft 2. Straight 3. Bends

Question 47

During blast cleaning, the air compressor must be able to deliver and maintain the required ___ ___ and ___ at the nozzle.

Answer 47

Air Volume and Pressure

Question 48

Equipment must be of the correct size and type to match compressor output, including; 1. ___ and ___ hoses. 2. Hose ___. 3. Blast ___.

Answer 48

1. Air and abrasive hoses. 2. Hose Couplings. 3. Blast Nozzles.

Question 49

Compressed air must be free of ___, including oil and water.

Answer 49

Contaminants.

Question 50

Most important in regards to a lack of contamination in compressed air: Since air supplied breathing equipment is required when abrasive blast operations are performed, it is critical that the breathing air meets ___ and ___ requirements. This is the responsibility of the operator unless otherwise designated.

Answer 50

Safety and legal.

Question 51

Second most important in regards to a lack of contamination in compressed air: It is important that the blast air is clean to ensure that blasting does not add ___ to the surface.

Answer 51

Contaminants.

Question 52

The blasting contractor is responsible for complying with all requirements of the ___, such as size of hose, type of nozzle, and air volume.

Answer 52

Specification.

Question 53

The coating inspector may check each of the requirements specified to ensure that blasting does not add ___ to the surface.

Answer 53

Contaminants.

Question 54

___ ___ is a common source of power for blast machinery, paint spray equipment, power tools, etc.

Answer 54

Compressed Air

Question 55

Compressed air is favored on site because it is relatively safe. It is less dangerous than?

Answer 55

Electrical power

Question 56

To produce the needed quantities of compressed air, it is necessary to use a?

Answer 56

Compressor

Question 57

A compressor draws in ___ ___, ___ it, and feeds the air into a pressure vessel, (known as a receiver) and directly into the item that requires it.

Answer 57

Atmospheric air, pressurizes it

Question 58

Producing compressed air presents two problems to the prep process. 1. Any change in atmospheric pressure can result in the release of ___ ___ from the air. 2. Because compressed air in the receiver is stored by ___ an ___ ___, it is possible that oil vapor remains in the air and is released. Both of these factor require fitting adequate 3. ___ ___ to blast cleaning equipment to remove oil and water contaminants.

Answer 58

1. Water vapor. 2. Pressurizing an oil reservoir. 3. Vapor/moisture traps.

Question 59

Compressors are rated for both ___ ___ and ___.

Answer 59

Air pressure and capacity.

Question 60

Air pressure is measured in ___ ___ ___ ___, pascals (Pa) or bar.

Answer 60

Pounds per square inch (PSI)

Question 61

Air pressure is normally set a little above the intended ___ ___. Normally a max of 100 psi for portable compressors.

Answer 61

Working pressure.

Question 62

The max air pressure for portable air compressors is usually ___.

Answer 62

100 PSI

Question 63

Air pressure, if successfully maintained, produces ___ blast cleaning.

Answer 63

Efficient

Question 64

Use air pressure no more than ___ __ and ___ allow. This may vary in different countries.

Answer 64

Safety considerations and regulations allow.

Question 65

Adequate pressure is critical to ___ ___.

Answer 65

Abrasive blasting.

Question 66

If the abrasive is not propelled at sufficient pressure, the job takes ___ to complete.

Answer 66

Complete

Question 67

Measure pressure at the nozzle with a?

Answer 67

Hypodermic needle gauge.

Question 68

Select a compressor that is able to supply 1___ ___ than is ___. This provides a reserve capacity for 2 ___ ___ or extra equipment.

Answer 68

1. More air than is required. | 2. Peak loads.

Question 69

The same compressor that powers blast equipment often also powers air-operated spray guns and other equipment. No other surface prep process requires such large quantities of compressed air as the?

Answer 69

Blast Cleaning

Question 70

It's estimated that with one 3/8 in. nozzle operating, there is a 1__ __ drop in air pressure for each 2__ ___ of hose in use. This pressure drop compounds depending on the number of operating nozzles, the nozzle sizes, and the lengths of hose in use.

Answer 70

1. 5 lb | 2. 50 ft

Question 71

Undersized compressors create inefficient that directly impact ___ and ___.

Answer 71

Cost and schedule.

Question 72

The use of undersized compressors may lead to: 1. Wasting time waiting for lower-capacity compressors to build up to the ___ ___. 2. Placing undue ___ on the compressor during peak loads. 3. Loss of time from inefficiently operating __-___ equipment. 4. Inability to ___ ___ ___ to the system. 5. Greater possibility of ___ or ___. 6. Excessive ___ to supply the quantity of air needed. 7. Excessive ___ and ___.

Answer 72

1. Required pressure. 2. Strain 3. Air-starved 4. Add new tools. 5. Breakdowns or shutdowns. 6. Running. 7. Heat and condensation.

Question 73

___ and ___ ___ are essential to maintain surface cleanliness during the blast cleaning operation.

Answer 73

Water and oil separators

Question 74

Without water/oil separators, the air compressor can carry ___ ___ or ___ ___ entrapped in the high-pressure air, or from residual dust arising during blast cleanings.

Answer 74

Oil vapor or Moisture droplets.

Question 75

Install suitable ___ and ___ ___, ___ ___ and ___ in the air lines and make sure they receive adequate maintenance.

Answer 75

Oil and Water Filters, After Coolers, and filters.

Question 76

Most oil and moisture traps operate with ___ ___ in a partially open position, allowing accumulated moisture to disperse.

Answer 76

Drain Plugs

Question 77

Moist air can also cause abrasives to clog the ___ ___ or ___ ___ and may cause rusting of the blast cleaned surface.

Answer 77

Abrasive lines or blast pot.

Question 78

Compressor Accessories: Filter units that contain 1___ and supply purified air to the blast hood. They also have monitors to detect the presence of 2___ ___.

Answer 78

1. Charcoal. | 2. Carbon Monoxide (CO).

Question 79

Compressor Accessories: | Absorbent filters to ___ ___ in compressed air and prevent condensation on the work piece.

Answer 79

Absorb moisture.

Question 80

Compressor Accessories: Drier units to remove water from the compressed air and prevent the ___ from becoming wet.

Answer 80

Abrasive

Question 81

Compressor Accessories: ___ to remove water by cooling and extracting moisture from the air stream, thereby preventing condensation on the work piece.

Answer 81

Refrigerant

Question 82

Warm air holds less moisture than cold air? True or False.

Answer 82

False. Cold air holds less moisture.

Question 83

Compressor Accessories: ___ ___ to remove water through centrifugal force.

Answer 83

Centrifugal Separators

Question 84

Compressor Accessories: ___ ___ ___ ___ to cool hot compressor air, thus removing moisture from the air stream.

Answer 84

Water-cooled heat exchangers.

Question 85

Compressor Accessories: An ___ ___ or ___ ___. These act as reservoirs of compressed air. One or more compressors feed air in until it is needed to power the tools/operations connected to the tank.

Answer 85

Auxiliary Receiver or Storage Tank.

Question 86

A compressor accessory, these act as reservoirs of compressed air.

Answer 86

Auxiliary Receivers or Storage Tanks