NACE - National Association of Corrosion Engineers Inspection Instruments and Tests Questions and Answers

Question 1

An inspector is required to measure the dry film thickness (DFT) of a coating system on a large, flat steel surface totaling 500 square meters (approx. 5,000 sq ft). According to SSPC-PA 2, how should the inspector determine the number of areas to measure?

Accepted Answer

Measure three 10 m² areas for the first 100 m², and then one additional 10 m² area for each subsequent 100 m².

Answer

SSPC-PA 2 specifies a clear procedure for determining the number of measurements on large surfaces. For areas over 100 m² (approx. 1,000 ft²), the standard requires the inspector to measure three 10 m² (approx. 100 ft²) areas for the first 100 m², and then arbitrarily select and measure one additional 10 m² area for each additional 100 m² or increment thereof.

Question 2

Which of the following instruments is used to perform a quantitative pull-off adhesion test as described in ASTM D4541?

Accepted Answer

A portable adhesion tester with a loading fixture (dolly)

Answer

ASTM D4541, 'Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers', describes a quantitative method for measuring adhesion. This test involves affixing a loading fixture, often called a dolly, to the coating surface with an adhesive and then using a portable adhesion tester to apply a perpendicular force to pull the dolly off, measuring the force required for detachment.

Question 3

A coating inspector is preparing to conduct holiday testing on a new protective coating with a specified dry film thickness of 15 mils (381 microns) on a conductive substrate. Which type of holiday detector is most appropriate for this application?

Accepted Answer

A low-voltage, wet-sponge holiday detector

Answer

NACE SP0188 provides guidance on holiday testing. For coatings less than 20 mils (500 microns) thick on conductive substrates, a low-voltage (typically 67.5V or 90V) wet-sponge holiday detector is the recommended instrument. High-voltage detectors are used for thicker coatings and can damage thinner films if the voltage is not set correctly or is too high.

Question 4

An inspector uses replica tape and a micrometer to measure the surface profile of an abrasive blast-cleaned steel surface, following the procedure in NACE SP0287. What is the primary purpose of this test?

Accepted Answer

To measure the peak-to-valley depth of the surface anchor pattern

Answer

NACE SP0287, 'Field Measurement of Surface Profile of Abrasive Blast-Cleaned Steel Surfaces Using a Replica Tape', describes a method to quantify the surface roughness or anchor profile. The replica tape captures a reverse image of the surface profile, and a micrometer is then used to measure the thickness of the impression, which corresponds to the peak-to-valley height.

Question 5

During a coating application project, the specification requires adhesion testing according to ASTM D3359, Method A. This test is primarily intended for which of the following scenarios?

Accepted Answer

Field testing of coating systems greater than 5 mils (125 µm) in thickness

Answer

ASTM D3359 describes two methods for tape adhesion testing. Method A, the X-cut test, is primarily intended for use at job sites and for coating systems with a total thickness greater than 5 mils (125 µm). Method B, the cross-hatch test, is more suitable for thinner coatings, typically under 5 mils.

NACE - National Association of Corrosion Engineers Certification Practice Test

NACE - National Association of Corrosion Engineers Certification Practice Test

NACE - National Association of Corrosion Engineers Inspection Instruments and Tests Questions and Answers