Page 471 - Trenchless Technology Piping Installation and Inspection

Glossary of Terms 421

Fiberglass: A high strength material that is commonly layered with a felt
material to add reinforcement for the resin cured-in-place pipe.
Fillers: Materials used to enhance the capabilities of a resin system.
Film: Either an outer or inner material to protect the resin impregnated
tube from contaminants.
Flexural modulus: The slope of the curve defined by flexural load
versus resultant strain. A high flexural modulus indicates a stiffer
material.
Flexural strength: The strength of a material in bending expressed as the
tensile stress of the outermost fibers at the instant of failure.
Flight: The spiral plates surrounding the tube of an auger.
Fluid cutting: (1) An old trenchless method where pressurized fluid jets
are mainly used to provide the soil cutting action. (2) A process using
high-pressure fluid to wash out the face of a utility crossing without any
mechanical or hand excavation of the soils in the face. This method is no
longer allowed.
Fluid-assisted boring or drilling: A type of horizontal directional drilling
technique using a combination of mechanical drilling and pressurized
fluid jets to provide the soil cutting action.
Fold and form lining: Method of pipeline renewal in which a liner is
folded to reduce its size before insertion and reversion to its original
shape by the application of pressure, or heat, or both.
Fold and form pipe: A pipe renewal method where a plastic pipe
manufactured in a folded shape of reduced cross-sectional area is pulled
into an existing conduit and subsequently expanded with pressure and
heat. The reformed plastic pipe fits snugly and takes the shape of the ID
of the existing, old, or host pipe.
Force-main: A pipeline that conveys sanitary, combined, or stormwater
flow under pressure from a pumping (or lift) station to a discharge point
(treatment plant).

Forward rotation: The clockwise rotation of the auger as viewed from the
machine end.
Gel Time: The time, at which a catalyzed resin system will begin to cure,
creating internal heat and thus beginning to harden.
Geographical information system (GIS): A computer software system
designed to store, manipulate, analyze, and print geographically
referenced information.
Gravity sewer: A sewer that is designed to operate under open channel
conditions (below pipe full capacity) up to a maximum design flow at
which point it will become surcharged.