bulk tubing and fittings before and during fabrication
of a tube assembly. Before replacing a defective tube
assembly, find the cause of failure, and inspect the
tube assembly before and after its installation.
Inspect in-service tube assemblies at regular intervals
in accordance with applicable maintenance directives.
When you inspect the tube and tube assemblies for
damage, look for chafing, galling, or fretting, which
may reduce the ability of tubing to withstand internal
pressure and vibration.
Replace tubing that shows
visible penetration of the tube wall surface caused by
chafing, galling, or fretting. Tubes that have damage
(nicks, scratches, or dents) caused by careless
handling of tools are acceptable if they meet the
following requirements: Any dent that has a depth
less than 20 percent of the tubing diameter is
acceptable unless the dent is on the heel of a short
bend radius. A nick or scratch that has a depth of less
than 15 percent of the wall thickness of aluminum,
aluminum alloy, or steel tubing should be reworked
by burnishing with hand tools before it is acceptable.
Any aluminum, aluminum alloy, or steel tubing
carrying pressures greater than 100 psi with nicks or
scratches greater than 15 percent of wall thickness
should be replaced.
Inspect each fitting (fig. 6-20) before it is
installed. Visually or flow check to make sure that
fitting passage or passages are free from obstructions.
Figure 6-20.—Damaged fittings.
6-20
