MIL-HDBK-1003/8A
Aboveground
Underground
Lower first cost
Less heat loss on hot lines
Less vulnerable target
Less maintenance
Less obstruction to aboveground
traffic
Easy detection of failure
Less unsightly
Higher continuous operating
Freeze protected when buried
efficiency
Longer life
Less heat gain in chilled and
condenser water piping
3.3.6.7
Piping Layouts. The project designer is responsible for
determining location of expansion bends, loops and joints, anchors, takeoffs,
isolation valves, and drip points. The project designer is also responsible
for locating all manholes, takeoffs, isolation valves, and drip points. The
system designer determines the initial location of anchors, expansion bends,
loops and joints; the system supplier determines final location and design of
these features to fit actual field conditions. Plan and position piping
layouts as follows:
a) Determine what lines between the same points should be parallel
to each other (such as supply and return) or be separated (such as steam from
chilled water). The minimum clearance between pipe conduits in the same
trench shall be 6 inches (150 mm).
b) Determine locations of expansion bends or loops, anchors,
takeoffs, and drip points. In non-pre-engineered/prefabricated heat
distribution systems, the project designer is responsible for determining
location of expansion bends, loops and joints; anchors; takeoffs; isolation
valves; and drip points. In pre-engineered/prefabricated heat distribution
systems, the project designer is responsible for locating all manholes,
takeoffs, isolation valves and drip points. Initial location of anchors,
expansion bends, loops and joints shall be by the system designer. The system
designer determines the initial location of anchors, expansion bends, loops
and joints; the system supplier determines final location and design of these
features to fit actual field conditions.
c) Lay out piping on a scaled contour map of the site and on a
profile drawing along the route, locating all obstructions and interferences,
such as streams, roads, railroads, buried tunnels, concrete trenches, drainage
piping, sewers, water piping, electrical conduits, and other service piping,
within 25 (7.6 m) feet of the center line of the right-of-way and identify
areas within 25 feet of the center line that must be avoided. If sufficient
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