FED-STD-228A
Method 1313.1
18 April 2014
THICKNESS, LEAD SHEATH; MICROMETER CALIPER
(FLAT 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 cannot be removed from the
wire or cable without distortion.
2. SPECIMEN
2.1 The specimen should be a piece of the inspection unit at least 2 feet in length from which any
covering over the lead sheath has been removed.
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 flat surfaces on both anvil
and end of spindle, each approximately 0.25 inch diameter. The surfaces of anvil and spindle shall be
parallel to within 0.0001 inch.
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. The
micrometer caliper shall be applied directly over the lead sheath so that the anvil and the spindle are just
brought into contact with the specimen in such a manner that the lead sheath is not distorted. The
criterion of contact is the initial development of frictional resistance to movement of the specimen
between the micrometer surfaces. The diameter over the sheath shall be read from the micrometer scale
and the value recorded as D1.
4.2 The lead sheath shall then be removed from the specimen and the diameter over the core (assembly
under the lead sheath) determined and the value recorded as D2. The micrometer caliper shall be applied
directly over the core so that the specimen can just be moved between the anvil and spindle without
distortion of the core.
4.3 Three sets of measurements equally spaced along the length of the specimen shall be made. Each
set of measurements shall consist of the maximum and minimum diameter at the place measured. The
diameter over the sheath and over the core shall be determined as nearly as practicable at the same
point.
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