A number in parentheses indicates the year of last reapproval. This standard has been approved for use by agencies of the Department of Defense. Scope 1. There are additional techniques suitable for laboratory use not covered by these test methods. The values given in parentheses are for information only.
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The test is performed just after sandblasting; the selected spot is cleaned by blowing air to remove loose dust that is the product of sandblasting.
Two type of replica tapes is available in the market i. The surface profile measurement almost is a mandatory requirement by most coating specifications. The "Coarse Tape" was made for the surface profile of 0.
You should pick the replica tape which is much closer to your customer specification. So if the customer specification requires 2 thru 3 mil surface profile, then you have to use Extra Coarse tape. Surface Profile Measurement Procedure Remove the cover from the tape and adhere to the surface and rub the little circle thin foam film with rounded objects. A swizzle stick comes with replica test package that you can use as a rounded object.
Then remove the replica tape and measure the thickness of the circle area thin foam film with a calibrated anvil micrometer. Record the micrometer value and deduct from 2 mil this is foam film thickness.
The obtained value from this subtraction is your surface profile. The test should be repeated if the obtained value is out of the range of testex tape replica test. For instance, if the specification says the required surface profile is 1 - 1. The replica test is more accurate when the readings after deduction of 2 mil falls near middle specified range.
For example, if you are using the extra-coarse tape and your test result is 3 mil, you can assure this reading is the accurate measurement.
You need to repeat the test with higher or lower grade when the reading is near the ends of the range. For example, if you are using extra coarse tape and your surface profile measured was 4. It is imperative for the inspector to witness the surface profile or review the test report.
The too shallow surface profile might cause lack of adequate adhesion and consequently cause the paint delamination and blistering. A higher surface profile might also create some problem; the high peak might not be covered with the first layer primer and create rust spot.
Some paint type also might have some limitation on surface profile, and "too high" surface profile be determinantal for painting process like inorganic zinc silicate primer.
Surface Profile Measurement by Replica Tape
For hot-dip galvanizing applications, it is possible to measure and verify the steel surface profile according to ASTM D, Standard Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel, prior to application of repair materials where the surface has been prepared via power tool or abrasive blast cleaning methods. Recent changes to ASTM D provide updated test methods to reflect the latest advances in technology and newly accepted industry research. The three test methods described within D for measuring surface profile include visual comparators, surface profile depth micrometers, and replica tape. Larger repair areas or prepared hot-dip galvanized surfaces for painting can be measured with 10 readings taken from a minimum of three, 6x6 inch 15x15 cm areas. The standard does not address discarding outliers, but an update to the standard addressing outlier readings is planned.
More D For this reason, surface profile should be measured prior to coating application to ensure conformance of a prepared surface to profile requirements specified by the manufacturer of a protective coating or the coating job specification. The instruments described are readily portable and sufficiently sturdy for use in the field. According to research performed by Roper, Weaver and Brandon6, an increase in peak count can improve the adhesion of some coatings to the prepared steel, as well as provide greater resistance to corrosion undercutting once the coating becomes damaged in service.
ASTM D4417 - 11 Standard Test Methods for Field Measurement of Surface Profile of Blast Cleaned.pdf
Mukora This material provides general information only and is not intended as a substitute for competent professional examination and aastm as to suitability and applicability. The three test methods described within D for measuring surface profile include visual comparators, surface profile depth micrometers, and replica tape. Method C Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Surface profile is defined as a measurement of the maximum peak-to-valley depth created by abrasive impingement against a surface during abrasive blast cleaning operations, or by an impact-type power tool.
Differences in Surface Profile Measurements: ASTM D4417- Method B vs. Method C
Surface profile is defined as a measurement of the maximum peak-to-valley depth created by abrasive impingement against a surface during abrasive blast cleaning operations, or by an impact-type power tool. During abrasive blast cleaning, the mass of the abrasive and the velocity of the abrasive movement created by compressed air generates kinetic energy the abrasive can reach speeds of over miles per hour as it exits the blast nozzle. When the abrasive impacts the surface, it cuts into the surface angular abrasives or peens the surface round abrasives and creates a series of peaks and valleys in the surface. The creation of this peak-valley pattern in the surface effectively increases the surface area, providing an anchor for the coating system. Both the structure and the coating system protecting the structure will move while in service. This movement may be caused by expansion and contraction of the substrate due to temperature fluctuation, or live loads placed onto a structure; for example, traffic crossing a bridge. The surface profile must be compatible with the coating system.