Type 2 DFT Instruments

Question 1

Electronic Gauges are referred to as Type 2 gauges in?

Answer 1

SSPC-PA 2

ASTM D7091

Question 2

Type 2 gauges use a measuring probe and the 1___ ___, ___ ___, and/or ___ ___ measurement principles in conjunction with 2 ___ ___ to produce a coating thickness measurement.

Answer 2

1. Magnetic Induction, Hall Effect, and/or eddy current.

2. Electromagnetic Microprocessors

Question 3

Some gauges have fixed ___ probes, ___ probes or a combination of both.

Answer 3

Integrated probe, separate probes, or a combination.

Question 4

There are numerous standards that govern DFT Measurements.

Answer 4

The only two we give a shit about are:

SSPC-PA 2

and

ASTM D 7091

Question 5

With regards to type 2 gauges you must check the 1___ for applicable standards, then consult the manufacturers’ data sheet to make sure your device complies.

Answer 5

Specification.

Question 6

To confirm the accuracy of your type 2, measure the thickness of a series of referenced standards such as ___ or ___ ___ ___.

Answer 6

Shims or coated metal plates.

Question 7

If the gauge is dropped, or suspected of giving erroneous readings:

Answer 7

Recheck its accuracy.

Question 8

Adjustment or Calibration adjustment refer to the adjustment of a gauges thickness measurements to match that of a know sample. This is done to improve the effectiveness of the gauge on a ___ ___ or in a ___ ___ of it’s measurement range.

Answer 8

Specific surface or in a specific portion of its measurement range.

Question 9

Sometimes, gauge readings are influenced by changes in substrate 1___, ___, ___ ___ or my changes in measurement location. To account for this, manufacturers make calibration adjustments possible for type 2 gauges. Always make adjustments based on the 2___ ___.

Answer 9

1. Shape, composition, surface roughness.

2. Manufacturers instructions.

Question 10

Sometimes, gauge readings are influenced by changes in substrate 1___, ___, ___ ___ or my changes in measurement location. To account for this, manufacturers make calibration adjustments possible for type 2 gauges. Always make adjustments based on the 2___ ___.

Answer 10

1. Shape, composition, surface roughness.

2. Manufacturers instructions.

Question 11

Adjust type 2 gauges to account for the 1___ ___. This allows the gauge to read the coating thickness directly.

Answer 11

1. Surface Profile.

Question 12

___ ____ ___ uses a single shim which is at, or close to, the upper thickness to be measured.

Answer 12

1. Single point Adjustment.

Question 13

With this method a shim, at or near the top of the expected measuring thickness is placed against the blasted surface and ten readings are taken. The average of those readings, if correct, ensures the gauge reads the thickness of the coating and not the surface profile.

Answer 13

Single point adjustment.

Question 14

This method of adjustment uses two shims, one above and one below the expected film thickness range to be measured.

Answer 14

Two point adjustment.

Question 15

With 1___ ____ ___, two shims are used. One 2___, and one 2___ the expected thickness range to be measured. Because protective coatings are normally applied to blast cleaned surfaces a statistical approach must be used to obtain a typical value for the adjustment. Ten measurement on each shim is sufficient to establish a reliable average value for the roughened surface.

Answer 15

1. Two point adjustment.
2. Above
3. Below

Follow the manufacturers instructions for adjusting the gauge to match each shims thickness value. This method ensures that the gauge reads the thickness of the coating over the peaks of the profile.

Question 16

1___ ____ ___

Sometimes a blasted substrate is not available for adjustment. Place the shims on a bare steel plate that is at lease 3x3 inches free of mill scale and rust. If the surface of the plate does not have a profile and the coated surface does, estimate a offset value for the profile to substrate from the measurement made.

Answer 16

1. Smooth Surface adjustment.

* As noted in ISO 19840

Question 17

Another adjustment procedure is to create a 1____ __ sample. Use a small steel sample, approx 2____ inches, then blast clean it according to the specification at the start of the project. This will allow you to check surface profile and DFT gauge measurements. Ensure it is made of similar 3___ with a similar 4___ and ___ to the structure being coated.

Answer 17

1. Reference Panel
2. 6x4 Inches.
3. Material
4. Thickness and Shape

Question 18

Before taking measurements, consider the many factors that influence which gauge to choose and which procedure to use. Factors to consider may include:

1. Type of ___
2. Anticipated coating ___ ___
3. ___ requirements.
4. ___ to follow.

Answer 18

1. Type of substrate (ferrous or nonferrous).
2. Anticipated coating thickness range.
3. Specification requirements.
4. Standards to follow.

Question 19

Some gauges automatically sense the substrate an select the correct principle of operation?

Answer 19

Eddy current or magnetic.

Question 20

Gauges have different measuring ranges. Choose the gauge whose measurement range is not only closes to the thickness range needed but also has optimum accuracy and?

Answer 20

Resolution.

Question 21

Some specifications require special adjustment and measurement procedures to follow. Sometimes they even state?

Answer 21

Which gauge to use.

Question 22

Depending on various factors reference and follow the ___ ___ that govern proper calibration, verification, adjustment and measurement procedures.

Answer 22

Specific Standard.

Question 23

Before taking measurements check the following:

1. Is the proper ___/___ for the substrate available.
2. Is the ___.___ appropriate for the anticipated DFT range?
3. Are the ___ in satisfactory working condition?
4. Has gauge accuracy been ___.
5. Is the calibration adjustment procedure ___ and ___.
6. Has the operation manual for the gauge been ___.
7. Have the ___ and ___ that govern how measurements are taken been reviewed.

Answer 23

1. Probe/Gauge
2. Probe/gauge.
3. Batteries.
4. Checked.
5. Known and understood.
6. Reviewed.
7. Specification and standards.