This guide specification covers the
requirements for an insulated underground heat
distribution system (UHDS) and/or condensate return
system of the pre-engineered type as covered in
TM-5-810-17 "Heating and Cooling Distribution
Systems", for steam and high temperature hot water
up to 230 degrees C (450 degrees F).This specification requires coordination with other
design disciplines (examples: cathodic protection,
trenching and backfill, structural for coordinating manhole structures). The specified systems are
capable of transporting steam, condensate, or high
temperature hot water. This specification is for
systems operating above 120 degrees C (250 degrees
F) to a maximum acceptable pressure and temperature
of approximately 2.800 Mpa (gage) (408 psig) and 230
degrees C (450 degrees F), respectively. It should
be noted that not all UHDS are acceptable for all
site classifications, temperatures, and pressure
ratings.
The Government designer will establish the site,
soil and groundwater conditions. The contract
drawings will show the size, proposed routing
(including construction limits) and estimated length
of the system. The contract drawings will establish
the elevations and show the profiles of the pipe and
the existing and finished earth surfaces. Indicate
and identify all obstructions within 8 m (25 feet)
of the system centerline, including adjacent or
crossing utilities.
This guide specification is not for the design of
the valve manhole and associated piping and
equipment in the valve manhole. Valve manholes and
the piping and equipment inside the valve manholes
will be designed and detailed on the contract
drawings. Section 33 60 01 VALVES, PIPING, AND
EQUIPMENT IN VALVE MANHOLES will be included as part
of this project. Include on the drawings a log of
soil conditions along the pipe line right-of-way, at
pipe depth, which gives, as a minimum, soil
classification, moisture content, soil resistivity
and pH, bearing strength and unstable conditions.