Destructive Instruments & Tests Flashcards
The inspector should not perform destructive testing unless what?
- Specification allows it
- Owner requires or allows it
- Tests are required for failure analysis
What is ASTM D 4752?
Test Method for Measuring MEK Resistance for Ethyl Silicate Zinc Rich Primers by Solvent Rub
What is ASTM D 5402?
Standard Practice for Assessing the Solvent Resistance for Organic Coatings Using Solvent Rubs
What is ASTM D 4138?
Measurement of DFT of Protective Coating Systems by Destructive Means [Method A]
Describe the solvent sensitivity test.
To perform the solvent sensitivity test:
• Select and clean area for test
• Fold 100% cotton shop cloth into 2 layers
- Approximately 300 mm x 300 mm (12 in. x 12 in.)
- Contrasting in color to the coating to be evaluated
• Saturate cloth with MEK and keep saturated during test
• Rub cloth back and forth on coated surface until substrate is revealed or for 50 double-rubs
• Assess results
• Compare with control area
What is the Scale of Resistance Reading for Inorganic Zinc (ASTM D 4752)?
5 = No effect on surface
4 = Burnished appearance, some zinc on cloth
3 = Some marring and apparent depression of film
2 = Heavy marring, obvious depression
1 = Heavy depression, no actual penetration to substrate
0 = Penetration to the substrate in 50 or fewer double-rubs
What is a Paint Inspection (Tooke) Gauge?
• Used to measure total coating thickness and the thickness of individual layers of coatings in multi-coat films
• May be used to see microscopic cracking, tendency for brittleness, blistering, or other microscopic anomalies
• May be used to inspect the substrate
• Used frequently in failure analysis
Describe the test procedure for a tooke gauge.
• Mark the surface
• Cut the coating at right angles to the pen mark by pulling the gauge towards you
Note: Must penetrate to substrate
• Position the gauge over the cut
• Turn on light
• Align the reticle scale parallel to the cut
Note: One side of cut straight edge, other ragged
• Measure the width of the cut coating (or coatings) by counting the number of graticule divisions
An elcometer 121-4 gauge requires calibration.
True or false?
False, it cannot be calibrated
What are the operating parameters of an elcometer 121-4 gauge?
Measures coating thickness with a DFT maximum of 2000 um (80 mils)
What are common errors made with an elcometer 121-4 gauge?
Common errors:
• Not applying enough pressure
• Pushing gauge away rather than pulling towards
• Reading results on the wrong side of the cut
• Using the wrong cutting blade for coating thickness
A saberg drill does not require calibration.
True or false?
True, this instrument does not require calibration
What are the operating parameters of a saberg drill?
Operating parameters:
• Measures coatings up to 1500 um (60 mils)
What are the common errors made with a saberg drill?
Common errors include:
• Using the incorrect hand wheel
• Using the wrong conversion factor
• Using excessive pressure when rotating the hand wheel
What is the difference between an elcometer 121-4 gauge and a saberg drill?
Elcometer 121-4 uses a cut
Saberg drill bores a hole
What is ASTM D 6677?
Evaluating Adhesion by Knife Destructive Test Method
What is ASTM D 3359?
Standard Test Method for Measuring Adhesion by Tape Test
What is ASTM D 3359 Method A
X-Cut Test Method for Measuring Adhesion by Tape Test
What is ASTM D 3359 Method B
Cross Hatch Test Method for Measuring Adhesion by Tape Test
X-Cut Test Method for Measuring Adhesion by Tape Test is used for coating films thinner than 5 mils.
True or false?
False, this method is used for coating films thicker than 5 mils
What are the ASTM descriptions to rate adhesion by the X-cut method (Method A)?
• 5A No peeling or removal
• 4A Trace peeling or removal along incisions or at their intersections
• 3A Jagged removal along incisions up to 1.6 mm (0.0625
in.) on either side
• 2A Jagged removal along most of incisions up to 3.2 mm
(0.125 in.) on either side
• 1A Removal from most of the area of the X under the tape
• OA Removal beyond the area of the X
Describe how to make cuts for the Cross Hatch (Method B)
If making the cuts individually:
• Cuts are made at right angles to each other
• Films thinner than 50
um (2 mils), 11 cuts 1 mm apart
• Films from 50 to 127 um (2 to 5 mils) thick, six cuts are made 2 mm apart
What are the ASTM descriptions to rate adhesion by the cross hatch method (Method B)?
• 5B The edges of the cuts are completely smooth; none of the squares of the lattice are detached.
• 4B Small flakes of the coating are detached at intersections;
less than 5% of the area is affected.
• 3B Small flakes of the coating are detached along the edges and at the intersections of the cuts. The area affected is 5 to 15% of the lattice.
• 2B The coating has flaked along the edges and on parts of the squares. The area affected is 15 to 35% of the lattice.
• 1B The coating has flaked along the edges of cuts in large ribbons, and whole squares have detached. The area affected is 35 to 65% of the lattice.
• OB Flaking and detachment worse than Grade 1B.
