UFC 4-390-01
23 July 2003
operation, should be equipped with appropriate pressure venting
capabilities. Lines which are required to be disconnected during
set-up and take-down of the unmanned pressure test facility must
be provided with suitable caps or plugs to maintain cleanliness
and prevent damage to threads. Both male and female connections
should be so protected. Caps, which introduce moisture, and
tapes, that leave adhesive deposits, should not be used for this
purpose. Closure devices, when not in use, should be stored in a
way that prevents contamination.
B.8.1.5.1 Welded Pipe Joints. Welded pipe joints are the
preferred method of joining pipe that will not require
disassembly for system repair or maintenance. The welding
process melts the base metal to form a joint that is often as
strong as the surrounding piping and resists cracking due to
piping flexure. Welded pipe joints must meet the requirements of
ASME B31.1 and supplemental requirements of the SCA.
B.8.1.5.2 Brazed Pipe Joints. Brazed pipe joints are used to
permanently join piping material that is not weldable (i.e.,
copper and copper-nickel). Brazed joints are not as strong as
welded joints because the process only melts a soft filler metal,
not the base metal. Brazing of austenitic stainless steels
should not be performed without express permission of the SCA.
All unmanned pressure test facility brazed pipe joints should
meet the requirements of NAVSEA 0900-LP-001-7000, Category P-3a,
Special Category (I) and should be performed in accordance with
NAVSEA/NAVFAC-approved procedures.
B.8.1.5.3 O-Ring and Flanged Pipe Joints. Mechanical piping
unions and flanges include a wide variety of designs that rely on
a mechanical action (i.e., torquing of bolts or nuts) to compress
a soft seal. Flange fittings are most often used in designs for
large diameter shore-based liquid or steam system piping. The
use of face seal o-ring unions are recommended over bolted
flanges. MS boss fittings, with o-ring seals, are preferred over
threaded pipe joints because galling of the threads is less
likely and the threads are not relied upon to form the seal.
Additional design requirements for bolted flanges and blanks and
all alignment and assembly requirements for mechanical joints
should be in accordance with Navy Ships Technical Manual (NSTM),
Chapter 505 and ASME B-31.1.
B.8.1.5.4 Threaded Pipe Joints. Experience has shown that these
connections are susceptible to corrosion, shock and vibration
damage, and leakage. Consideration must be given to pressure
limitations due to a reduction in wall thickness of the pipe at
the tapered threads. Should a component only be procurable with
threaded end fittings, a means must be provided upstream and
downstream of the component to permit its removal without
disturbing the threaded joints. Any compound (e.g., antiseize
thread tape) or lubricant used in threaded joints should be
suitable for the service conditions and should not react
unfavorably with the service fluid or piping materials.
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