TM 5-852-9/AFR 88-19, Vol. IX
drill a water well either directly in the building to be served or immediately adjacent to it.
(1) Underfloor piping. Buildings in permafrost areas are usually elevated above ground on a piling
system. The area under the floor, therefore, is exposed to the cold arctic air and underfloor piping must be
protected from freezing. This protection can be accomplished in several ways.
(a) The utility lines underneath the building can be placed in insulated enclosures and the pipes
protected by heat to prevent freezing. See Figure 4-8 for a discussion on the advantages and disadvantages
of heat tracing methods. Heat can be applied by four methods:
First method: Heat cables made of a nonmetallic sheath can be wrapped spirally around the
pipe between it and the insulation. This technique provides uniform heating regardless of the quantity of liquid
within the pipe. Pipe insulation must be removed and reinstalled to replace the heating element.
Second method: A commonly used method is installation of a mineral insulated (MI)-type,
copper jacketed heat cable immersed in the liquid inside the pipe. Proper installation of the MI cable is critical
to provide long service life. Improperly installed MI cables have failed after being in service 1 to 2 years,
whereas properly installed cables last indefinitely. Proper installation involves the maximum use of straight
pipe runs with minimum cable bending. The cable must be factory fabricated to the proper length
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