MIL-HDBK-1003/8A
4.2.9
Finish and Protection. All noninsulated ferrous parts of the
piping, piping support system, or equipment will be hot-dipped galvanized or
primed with red oxide primer and painted with epoxy paint.
4.3
Concrete Trench Design. The concrete shallow trench will consist
of poured concrete sides and floor, with removable tops. Portions of the
floor may be omitted at locations outlined previously under course grained
soils with water table 2 feet (610 mm) or more below lowest point of water
entry.
4.3.1
Depth of Trench. Ensure the depth of the concrete trench is
sufficient to provide adequate protection to the piping system and, slope the
floor of the trench to provide adequate internal drainage, but in all cases
not less than 6 inches (150 mm) from the bottom surface of the suspended pipe
insulation to the floor of the trench. Ensure there is a minimum of 3 inches
(75 mm) between the surface of the pipe insulation and the adjoining trench
walls and a minimum of 4 inches (100 mm) between surfaces of adjacent pipe
insulation.
4.3.2
Drainage of Trench. Base the design on sound engineering practices
which provide for drainage under all anticipated conditions. Consider the
annual rainfall, water table, and other topographic conditions in the basis
for the design. For those instances where natural drainage cannot be provided
(storm water drainage system at least 2 feet (610 mm) below trench bottom at
all times), provide a dual sump pump capability with failure annunciator.
4.3.3
Tops. The tops of the concrete trenches will be removable by use
of a portable lifting device such as a forklift or backhoe, and can also be
used for sidewalks, if practical. Earth must not cover the tops. Covers will
be close tolerance fit with a maximum gap tolerance build up of 0.12 inch from
all causes.
4.3.4
Details. Design the Concrete Shallow Trench Heat Distribution
System and show on the contract drawings. Use Figures 12 through 23 as
appropriate.
Provide the following information on the contract drawings for the
concrete Shallow Trench System, as applicable: dimension on all runs of pipe;
elevations of the pipe along the systems path; sizes of the pipe; location of
all valves; location and details of all expansion loops, Z- and L-bends;
location of pipe anchors; how changes in pipe direction are made; thickness of
the insulation on the pipe; concrete trench details; final elevations of
concrete trench; profile of trench showing all existing utilities; manhole
dimensions; manhole cover details; how manhole is drained and vented where
required; sump pump piping details; sump pump capacity; condensate pump
capacity and details; include specific requirements for modification to
existing; steam drip trap locations and capacity; steam pressure reducing
valve capacity and details; and other pertinent information and details
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