Page 486 - Trenchless Technology Piping Installation and Inspection

436 App endix D

Trenchless rehabilitation: See renewal.

Trenchless technology: Also NO-DIG, techniques for underground pipeline
and utility construction and replacement, rehabilitation, renovation
(collectively called renewal), repair, inspection, and leak detection, etc.,
with minimum or no excavation from the ground surface.
Tube: The fabric material tube used to carry and hold the thermoset
resin materials in place against the existing pipe prior to curing.

Tuberculation: Localized corrosion at scattered locations resulting in
knob like mounds.
Tunnel: An underground conduit, often deep and expensive to construct,
which provides conveyance and/or storage volumes for wastewater,
often involving minimal surface disruption.
Tunnel boring machine (TBM): (1) A full-face circular mechanized shield
machine, usually of worker-entry diameter, steerable, and with a rotary
cutting head. For pipe jacking installation it leads a string of pipes. It may
be controlled from within the shield or remotely such as in microtunneling.
(2) A mechanical excavator used in a tunnel to excavate the front face of
the tunnel (mole, tunneling head).
Ultra violet light cure: See light cure.
Uncased bore: Any bore without a lining or pipe inserted, that is, self-
supporting, whether temporary or permanent. Not recommended except
in special conditions.
Underground utility: Active or inactive services or utilities below ground
level.
Upset: See machine upset.
Upsizing: Any method such as pipe replacement or pipe bursting that
increases the cross-sectional area of an existing pipeline by replacing with
a larger-diameter pipe.
Utility tunneling: It is general approach of constructing underground
utility line by removing the excavated soil from the front of cutting face
and installing liner segments to form continuous ground support
structures. The product pipe is then transported and installed inside the
tunnel. The annular space between the liner and the pipe is usually filled
with grout.
VCP: Vitrified clay pipe.
VCT: Vitrified clay tile or vitrified clay tile pipe.
Velocity head: For water moving at a given velocity, the equivalent head
through which it would have to fall by gravity to acquire the same
velocity.
Vinyl-ester: Resin systems used for many industrial applications
requiring a higher level of corrosion resistance.