Change 2, 30 December 1991
GENERAL DESIGN FACTORS
Design Responsibilities for Underground Pre-engineered Heat
Distribution Systems. The project designer is responsible for accomplishing
the following prior to project bidding:
a) Define site conditions for underground water classification (A,
B, C, or D), soil corrosiveness, soil pH if less than 5.0, and potential soil
load bearing problems.
b) Determine the general layout and essential characteristics of
the system such as system media, maximum operating temperature and pressure,
location and design of manholes, and branch runouts. The interface detail of
the system at manhole walls shall be provided by the system supplier.
Design special elements of the system as required.
d) Calculate the maximum heat loss per lineal foot of the conduit
in accordance with the procedures outlined in NFGS-02694.
Design by Project Designer. The project designer shall design on
the manholes, piping within manholes, and piping not in approved conduit
systems. The project designer shall establish the system design parameters of
the entire underground piping system, such as site classification, general
layout, essential characteristics of the system, and specially designed
elements of the system. The project designer is responsible for sizing the
pipe, establishing the piping elevations, identifying the piping right-of-way,
obstructions and utilities (plan and profile) within 25 feet (7.62 m) of the
center line of the right-of-way, and every area within 25 feet of the center
line that must be avoided; for example, paved areas and buildings. The
project designer is also responsible for the location and sizing of manholes,
the design of concrete manholes and the piping and equipment layout of
manholes including valves, fittings, traps, expansion joints (when required),
and manhole drains.
Design by System Supplier. The construction Contractor shall
design and provide buried factory-prefabricated preinsulated piping in a
conduit or pre-engineered insulated piping system for which a Federal Agency
Approved Brochure has been issued. It is intended that the supplier of a
Federal Agency approved system provide the details of design for his system in
accordance with his Federal Agency Approved Brochure. The preapproved
brochure and the design will address expansion loops, bends, offsets, concrete
pipe anchors outside of manholes, interface with each manhole, and the
watershed to aboveground piping. When prefabricated steel manholes are
indicated, the system supplier is responsible for the structural design of the
manhole and the manufacture of the complete manhole, including installation of
valves, fittings, and other equipment as specified herein and indicated on the