The inserts covered by this specification are intended for use in original design application, especially in soft materials, to provide protection against thread failures caused by stripping, fatigue, wear, corrosion, and seizing. They are also intended for use in the repair of damaged or worn threads not originally protected. The class 2 insert which has prevailing torque capabilities provides protection to the joint against loosening caused by vibration and impact loading, thus obviating the use of lock washers, lock wires, or other means of locking.

Scope.  This specification covers helical coil screw-thread inserts made
from formed wire, the inner surfaces of which, after assembly, provide
threads as specified.

Classification.  Inserts shall be of the following types and classes, as
specified (see 6.2).

a.  Type I - Coarse thread

    (1) Class 1 - Free running.

    (2) Class 2 - Screw locking (self-locking)

b.  Type II - Fine thread

    (1) Class 1 - Free running

    (2) Class 2 - Screw locking (self-locking).

c.  Type III - Taper pipe thread

    (1) Class 5 - NPT pipe thread

    (2) Class 6 - ANPT pipe thread

THE INITIAL RELEASE OF THIS DOCUMENT SUPERSEDES MIL-I-8846, REVISION D,
AMENDMENT 1, SUPPLEMENT 1.

                         LIST OF CURRENT SHEETS

                      NO.  REV  NO.  REV  NO.  REV

                      1    NEW  6    NEW  11   NEW

                      2    NEW  7    NEW  12   NEW

                      3    NEW  8    NEW  13   NEW

                      4    NEW  9    NEW

                      5    NEW  10   NEW

d.  Type IV - Metric-spark plug thread

    (1) Class 3 - Staking (spark plug thread)