MIL-HDBK-1003/8A
c) Other Hazards. When piping must be laid where it will be
subjected to hazards such as earthquakes, washouts, floods, unstable soils,
landslides, dredging of water bottoms and other categorically similar
conditions, protect it by increasing pipe wall thickness, constructing
intermediate supports or anchors, erosion prevention, covering pipes with
concrete, adding seismic restraints for above-grade piping or other reasonable
protection.
d) Manholes. Select manhole locations in accordance with the
following. Details of piping and design of manholes are the responsibility of
the project designer. Design manholes to provide adequate space for
maintenance, proper venting and quick egress. Manholes are required where
vertical offsets in steam piping are required to conform to grading
requirements. Manholes accommodate the required steam main drip traps and any
block valves needed. Manholes are usually provided at all major branch line
connections and at drip traps on compressed air lines.
e) Tunnels. Construct tunnels for underground routes with a
walkway minimum height of 76 inches (1.93 m) and clear width of 36 inches
(920 mm), with piping stacked vertically on one side and enlarged zones for
crossovers and takeoffs. Label all pipes and conduit. Provide enough room to
reach all flange bolts, to operate tools, and to operate or to replace any
component. Run a drainage trench along one wall to a point of disposal such
as a storm sewer or a sump pit, with an automatic drainage pump driven by an
electric motor or steam jet. Install all electrical systems in rigid metal
conduit. Identify and separate by voltage class. Tunnels shall be well
lighted and ventilated. Use moisture resistant electrical fixtures. Tunnels
may be built of reinforced concrete, brick, or other suitable structural
materials, and shall be membrane waterproofed.
3.3.6.5
Condensate Return Cost.
Refer to para. 4.1.2 and 4.2.2.3.
3.3.6.6
Choice of Route. Except in congested and vulnerable areas, choose
aboveground routes for heat distribution systems. Otherwise, adapt site
conditions to comparative advantages of going above or underground as stated
below:
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