Ch. 7 Waterjetting

Question 1

Is the WJ-1 (Visual cleanliness) comparable at any abrasive blast cleaning standard?

Answer 1

equivalent to SA 3, cleaning to bare metal also intended to be similar to NACE No. 1/SSPC-SP 5, except that stains are permitted to remain on the surface.

Question 2

A general description of robotic waterjetting includes

Answer 2

Attaches using vacuum, cables, or magnets
vertical, horizontal or overhead surface
*Controlled by single operator
*Collects in excess of 95% of the water, removed coatings and rust {waste management generated}

Question 3

Waterjetting is effective for removing

Answer 3

surface oil and grease
rust
concrete {shot-crete} spatter
existing coatings
water soluble contaminants that cannot otherwise be removed by abrasive blasting
an underwater unit used to clean barnacles or other micro-organisms for ship hulls or off shore platform legs.

Question 4

Describe two of the considerations with regards to “back thrust”

Answer 4

• Causes fatigue

* No more than 1/3rd of their body weight for an extended period of time.

Question 5

To ensure a safe work place before beginning the job, the waterjet team should ensure that

Answer 5

• the work area is properly barricaded
• electrical equipment protected from water
• electrical connections are not allowed to sit in water
• all fittings and hosed are in good condition/proper pressure rating
• nozzles free of obstructions
• system is flushed clean and air removed
• the dump system and all control systems are operational
• proper LOTO provisions/confined space entry requirements

Question 6

Waterjetting advantages include

Answer 6

worker safety
worker air quality
less stringent respiratory requirements
no dust contamination or cleanup
friendly to the environment
relatively cost efficient
it requires less clean up

Question 7

Disadvantages of waterjetting include

Answer 7

the surface must have a profile {waterjetting leaves no profile}
equipment is very expensive
danger of UHP hose breaking
danger of injection into the skin or serious cuts
collecting and disposing of the contaminated water
proficient operators

Question 8

Degrees of flash rust

Answer 8

No flash rust
Light Flash rust
Moderate flash rust
Heavy flash rust

Question 9

After waterjetting at pressures of (20,000 psig) the surface appearance will resemble

Answer 9

A uniform matte finish that will quickly turn golden unless an INHIBITOR is added or DE_HUMIDIFICATION is used

Question 10

when operating at pressure of 4,000 psi or higher the water jetting team consist of

Answer 10

nozzle operator, pump operator, and additional operators or worker.