MIL-STD-167-1 Mechanical Vibrations Of Shipboard Equipment Type I - Environmental And Type Ii - Internally ExcitedThis standard specifies procedures and establishes requirements for environmental and internally excited vibration testing of Naval shipboard equipment installed on ships with conventionally shafted propulsion see 6.1.e and 6.1.f.

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MIL-STD-167-1A

5.1.4  Extension of previous testing.  Equipment, which is identical or similar to previously tested equipment, may qualify for an extension of the previously approved test.  The equipment for which the testing is to be extended must meet all of the following criteria:

a.        The tested equipment and the proposed extension equipment are made of the same or similar materials and manufactured using the same or similar processes.

b.        The mass of the proposed extension equipment is no more than 10% greater than the mass of the tested equipment.

c.        The location of the center of gravity of the proposed extension equipment is within 10% of the location of the center of gravity of the tested equipment.

5.1.4.1  Extension documentation.  A request for extension of previously approved testing must be approved by the acceptance authority and must contain the following:

a.    Detailed drawings of both the tested equipment and proposed extension equipment. b.    A copy of the test report for the tested equipment.

c.        A detailed comparison of the differences in materials and design showing that the proposed extension equipment has equal or greater vibration resistance than the tested equipment.  This comparison should include at a minimum the information requested in sections 5.1.4.a, b, and c.

5.2  Type II - internally excited vibration.  Type II balance and vibration requirements shall apply to the procurement of rotating machinery, unless otherwise specified (see 6.2.e).  This does not apply to suitability from a noise standpoint, nor does it apply to reciprocating machinery.  Special vibration and balance requirements may be specified (see 6.2.g(1)).  The limitations set forth herein may also be used as criteria on overhaul tolerances, but should not constitute a criterion for the need for overhaul.

5.2.1  Basis of acceptability.  All rotating machinery shall be balanced to minimize vibration, bearing wear, and noise.  Types of balancing shall be as specified in Table IV.  Machinery with rigid rotors shall meet the limits of allowable residual unbalance given in 5.2.2.2.  Machinery with rotors which are unable to meet the balance requirements of rigid rotors shall be balanced in accordance with the requirements of 5.2.3.1.

TABLE IV.  Types of balancing.

1/   L - Length of rotor, exclusive of shaft.

D - Diameter of rotor, exclusive of shaft.

5.2.2  Balance procedure for rigid rotors.

5.2.2.1  Balancing methods for rigid rotors.  Except for machinery operating below 150 rpm, all balancing shall be accomplished by means of balancing equipment requiring rotation of the work piece.  This may be either shop or assembly balancing type equipment.  The minimum detectable unbalance of the balancing machine used shall be below the residual unbalance specified in 5.2.2.2.  For machinery rated at lower than 150 rpm, the rotor including shaft, may be balanced by symmetrically supporting the rotor on two knife edges and applying correction to attain a static balance unless otherwise specified see 6.2.g(2)).

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