FED-STD-228A
Method 1311.1
18 April 2014
THICKNESS, LEAD SHEATH; MICROMETER CALIPER (ROUND ANVIL)
1. SCOPE
1.1 This method is intended for use in determining the thickness of lead and lead alloy sheath of
insulated wire and cable whenever a section of the sheath for measuring can be removed from the wire or
cable without distortion.
2. SPECIMEN
2.1 The specimen should be the sheath removed from a piece of the inspection unit at least 3 inches in
length. The sheath 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 directly 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 material shall be removed from the specimen by means of the cloth and solvent.
4.2 The micrometer caliper shall be applied directly to the specimen so that the anvil and spindle are just
brought into contact with the surfaces of the specimen (anvil in contact with inner circumference) in such
a manner that the sheath is not distorted. The criterion of contact is the initial development of frictional
resistance to movement of the sheath between the micrometer surfaces.
4.3 The thickness of the sheath at the place measured shall be read from the micrometer caliper scale
and the value recorded. 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 lead sheath of the inspection unit shall be the average of the results
obtained from the specimens tested.
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