ACTUAL Exam Questions and CORRECT
Answers
The concentrated area of blast created by a centrifugal blast machine is called the what? -
CORRECT ANSWER - Hot spot
What could be the cause of low amperage readings on a centrifugal blast machine? - CORRECT
ANSWER - - An abrasive-starved wheel
- A flooded or choked wheel
True or False : Abrasive blast machines clean best with a range of abrasives. - CORRECT
ANSWER - True
In a centrifugal blast operation, the degree of cleanliness is determined primarily by
__________. - CORRECT ANSWER - Speed of travel
What are some advantages of portable centrifugal blast cleaning? - CORRECT ANSWER --
Can be used for multiple substrates
- Dust can be collected for disposal
- Abrasives can be recycled
What are some abrasives that can be used in centrifugal blast units? - CORRECT ANSWER -
- Steel shot/grit
- Glass beads
,- Garnet
- Walnut shells
Low-Pressure Water Cleaning (LP WC) - CORRECT ANSWER - - Below 5,000 psig
- Also called "power washing" or "pressure washing"
High-Pressure Water Cleaning (HP WC) - CORRECT ANSWER - - 5,000 to 10,000 psig
High-Pressure Waterjetting (HP WJ) - CORRECT ANSWER - - 10,000 to 30,000 psig
Ultrahigh-Pressure Waterjetting (UHP WJ) - CORRECT ANSWER - - 30,000 psig and above
True or False : None of the standards (WJ-1 through WJ-4) specifies the amount of non visible
contaminants (soluble salts) that are allowed to be left on the surface. This is left up to the
specifier. - CORRECT ANSWER - True
Back Thrust - CORRECT ANSWER - - Causes fatigue
- Should be no more than 1/3 of the operators body weight
When using UHP waterjetting with an inhibitor, the steel surface after cleaning will appear
__________. - CORRECT ANSWER - - As a dull matte finish
You are a new inspector on a UHP waterjetting project. What is the typical distance between the
waterjetting tip and surface that you would expect to see? - CORRECT ANSWER - - 2 inches
(5 cm)
, Light (L) flash rusted surface: - CORRECT ANSWER - Not easily removed by lightly wiping
with a cloth
Moderate (M) flash rusted surface: - CORRECT ANSWER - Leaves light marks on a cloth
that is lightly wiped over the surface
Heavy (H) flash rusted surface: - CORRECT ANSWER - Leaves significant marks on a cloth
that is lightly wiped over the surface
Advantages of Robotic Waterjetting include: - CORRECT ANSWER - - Controlled by single
operator
- Collects in excess of 95% of the water, removed coatings, and rust (waste generated)
The waterjetting team consists of: - CORRECT ANSWER - - The nozzle operator
- The pump operator
- Additional operators or workers
Waterjetting is effective for removing: - CORRECT ANSWER - - Surface oil and grease
- Concrete (shot-crete) spatter
- Water-soluble contaminants
- Barnacles or other micro-organisms for ship hulls or off-shore platform legs