FED-STD-228A
Method 1211.1
18 April 2014
THICKNESS, METAL TAPE ARMOR
1. SCOPE
1.1 This method is intended for use in determining the thickness of flat metal tape or interlocking armor of
insulated wire and cable.
2. SPECIMEN
2.1 The specimen should be the tape or armor removed from a piece of the inspection unit at least 3
inches in length. The tape or armor should be removed in such a manner as to change its shape as little
as possible.
3. APPARATUS AND REAGENTS
3.1 The apparatus and reagents shall be as follows:
3.1.1 Micrometer caliper graduated to read in mils or 0.0001 inch and having a hemispherical anvil with a
radius of curvature of 0.125 ± 0.005 inch and a flat-surface spindle of approximately 0.25 inch in diameter.
3.1.2 Wiping cloth.
3.1.3 Alcohol or other suitable solvent.
4. PROCEDURE
4.1 The specimen shall be free from mechanical damage. Any dirt, grease, saturants, or other
extraneous materials shall be removed from the specimen by means of the cloth and solvent. In the case
of interlocking armor the specimen shall also be free from jointed sections.
4.2 The micrometer caliper shall be applied directly to the specimen so that the anvil and spindle is just
brought into contact with the surfaces of the specimen (anvil in contact with the inner circumference) in
such a manner that the tape or armor is not distorted. The criterion of contact is the initial development of
frictional resistance to movement of the tape or armor between the micrometer surfaces. The thickness
of the armor or tape at the place measured shall be read from the micrometer caliper scale and the value
recorded.
4.3 Five measurements equally spaced around the circumference of the specimen shall be made
5. RESULTS
5.1 Unless otherwise specified in the detail specification, two specimens, one from each end of the
inspection unit, shall be tested.
5.2 The average thickness of the armor or tape of the inspection unit shall be the average of the results
obtained from the specimens tested.
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