UFC 4-390-01
23 July 2003
B.8.1.5.5 Flared Pipe Fittings. Flared pipe fittings and their
joints should conform to the range of wall thicknesses and method
of assembly recommended by the manufacturer. Care should be
taken with cutting and flaring tools so as to not induce work
hardening of the tube end, which can make the material more
susceptible to brittle fracture. Flared fittings should not be
used without specific NAVFAC approval.
B.8.1.5.6 Flareless Pipe Fittings. Flareless, mechanical
friction or bite-type connections should not be used on piping
components where failure could cause uncontrolled
depressurization or flooding of pressure vessels, mission support
systems, electrical assemblies or other mission components. The
use of such fittings in control and monitoring systems may be
permitted only if:
a)
they can be quickly isolated from the rest of the
system in case of failure and,
b)
a redundant means of providing the control and
monitoring functions is available
Flareless and non-standard fittings, including proprietary
fittings, should not be used without specific NAVFAC approval.
Approval for joint design should be based on past experience
and/or tests that demonstrate that the joint is safe for the
operating conditions.
B.8.1.6 Flexible Hoses/Flexible Pipe. In most applications and
for permanent installations, flexible hose is a poor substitute
for rigid pipe or tubing. The use of flexible hose should be
limited to applications where excessive flexing or vibration of
rigid piping dictates its use. When hose is to be subjected to
considerable vibration or flexing, sufficient slack should be
provided to avoid mechanical loading. Sharp bends or twisting
should be avoided. Bend radii should not be less than the
manufacturer's recommended minimum bend radius. All hoses should
have a rated working pressure equal to or greater than the system
design pressure for the system in which they are used. A
pressure safety factor of four times the hose rated working
pressure to burst pressure should be the minimum used for
flexible hose. Flexible hose material should be compatible with
the intended service. Cleaning solutions must be compatible with
the hose materials and must be able to clean the hose to the same
level as the system in which it is used.
When hoses and connectors are used in applications where they may
be subjected to mechanical loading, they should be provided with
strain relief devices. These devices should be designed to
prevent damage to the hoses and connectors as well as to prevent
accidental disconnection of the hoses if they are pulled.
Provisions should be made to connect the strain relief device to
a nearby structural member. The most common form of strain
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