Table 15-4.--Volume Rate of Flow for Water (Not Feed)
VOLUME OF
ALLOWABLE
INTERNAL
THICKNESS
NOMINAL
FLOW
VELOCITIES
DIAMETER
(inches)
PIPING SIZE
(gallons per minute)
(feet per minute)
(inches)
(inches)
7.26
210
0.920
314
0.065
15.47
1.185
270
1
0.065
32.76
1.530
343
1-1/4
0.065
51.51
1.770
403
1-112
0.065
2.245
102.82
500
2
0.065
178.48
592
2.73 1
2-1/2
0.072
685
3 10.66
3.334
3
0.083
445.97
753
3.810
3-1/2
0.095
600.72
803
4.282
4
0.109
983.52
5.295
5
0.134
860
1,442.16
6.313
6
0.156
887
piping must not interfere with the maintenance or
The minimum thicknesses of pipe and tubing are
repairs of the machinery or ship's structure. If there is
determined by the stresses on the material. These
stresses will vary with the difference in operating
systems, machinery, or ship's structure, then the piping
temperatures and pressures. A manufacturing tolerance
is added to obtain a nominal wall thickness and to
should be installed so that it can be removed easily for
access to the material behind it. The location of cutoff
compensate for the decrease of the wall thickness
valves, unions, and flanges must be carefully planned.
caused by making bends in the pipe or tubing. Piping
These locations should isolate sections of piping with
used to carry seawater will have an extra allowance
added to compensate for corrosion. The various
military specifications for piping and tubing will also
rest of the system. Piping that is vital to the ship's
include information on the wall thickness to be used
propulsion system must not be installed where it would
for different applications.
have to be dismantled to allow routine maintenance on
machinery or on other systems.
DESIGN REQUIREMENTS
When the type of cutout valve is not specified,
select the one that is best suited for the service
The requirements governing the design and
condition. Sometimes, the pressure drop or turbulent
arrangement of shipboard piping systems are covered
flow characteristics of globe and angle valves will be
in detail by contract specifications and by a number of
harmful to the components of the system. In these
NAVSHIPS plans and drawings. The information
cases, a gate type is generally installed when no
given here is not intended as a detailed listing, but
throttling will be required.
merely as a general guide.
Avoid unnecessary high points and low points in
All shipboard piping systems must be installed so
piping systems. Where they are unavoidable, install
that they will not interfere with the operation of the
vents, drains, or other devices to ensure proper
ship's machinery or with the various doors, hatches,
scuttles, manhole covers, or inspection plates. Also, the
15-29