Chapter 10 Surface Preparation Flashcards
During surface preparation, surface cleanliness should be inspected ( at a minimmum) the following three times:
Before any surface preparation activities
After surface preparation, and before coating begins
Between each application of coating in a multi-coat system
Factors during surface preparation that may affect service life include:
Residues of oil, grease, and soil
Residues of (non-visible) chemical salts
Rust on the surface interferes with adhesion
Mill Scale
Surface Condensation
Old coatings
Existing Coatings
Common design defects include:
Hard to reach or inaccessible areas
Rivets, bolts, or other connectors
Welds
Gaps ( skip welds or surfaces close together )
Overlapping surfaces
Angle iron badly oriented or in complex arrangements
Threaded areas
Dissimilar metals
Sharp edges, particularly on corners or rough-cut plate
Common fabrication defects include:
Weld spatter, skip welds, sharp corners & edges
Four typical SSPC-SP1 pre-cleaning methods include:
Solvent wipe with cloth or rag
Immersion of the substrate in solvent
Solvent spray
Vapor degreasing
Steam cleaning
Emulsion cleaning
Chemical paint stripping
Use of alkaline cleaners
One standard to use with power tool cleaning is:
SSPC-SP3
Four examples of tools used for rotary power tool cleaning are:
Rotary wire brushes
Impact tools
Needle scaler
Disc sanders
Piston scalers
Two abrasive blasting methods include
Centrifugal blasting Sand-injected water blast Slurry blast Wet abrasive blast Dry grit blasting
Visual guides for abrasive blasting include:
SSPC-Vis 1
ISO 8501-1
SSPC-SP10/NACE 2 limits staining ______ per each unit area
5%
SSPC-SP5/NACE 1 limits staining to ______ per each unit area
0%
SSPC-SP6/NACE 3 limits staining to _______ per each unit area
33%
The two types of abrasive blasting nozzles include:
Straignt
Venturi
The specified level of surface cleanliness must be achieved and maintained
Immediately prior to coatings application
Advantages of centrifugal blast equipment include:
Dust and fines are contained
Abrasives are easily recycled
Blasting and priming can be an incline operation
General overall economy compared to air blasting
No compressors, piping, or air handling equipment needed for wheel blasting