Page 484 - Trenchless Technology Piping Installation and Inspection

434 App endix D

Spoil (muck): Earth, rock, and other materials displaced by a tunnel,
pipe or casing, and removed as the tunnel, pipe or casing is installed. In
some cases, it is used to mean only the material that has no further use.

Spot repair: See localized repair.
Spray lining: A technique for applying a lining of cement mortar or resin
by rotating a spray head, which is winched through the existing pipeline.
Springline: (1) An imaginary horizontal line across the pipe that passes
between the points where the pipe has its greatest cross-sectional width.
(2) Midpoint of a pipe cross section (equal vertical distance between the
crown and the invert of the pipe).

Standard dimension ratio (SDR): Standard dimension ratio is defined as
the ratio of the outside pipe diameter to wall thickness. Same as DR.
Static mixer: A computerized device that provides fast, uniform resin
and catalyst mixing.

Steering head: In horizontal auger boring, a moveable lead section of
casing that can be adjusted to steer the bore.
Styrene: A component of polyester and many vinyl ester resin systems.
Subsidence: The settlement of the ground, pipeline, or other structure.
The effects may not be evenly distributed and/or immediately noticeable.
Differential settlement may occur.
Sump: A depression usually in the drive pit to allow the collection of
water and the installation of a sump pump for water removal.
Swivel: In horizontal directional drilling, it is used to attach product
pipe (to be pulled into drilled hole) to drill pipe to prevent it from rotating.
Target shaft or pit: See reception or exit shaft or pit.

TBM: See tunnel boring machine.
Teeth: See bits.
Televise: Process by which a sewer, pipeline or lateral is inspected with
a closed-circuit television camera.

Thermocouple: A device used to measure the internal temperature of a
resin-saturated felt tube during the installation process.
Thermoformed pipe: A type of renewal method that uses polyvinyl
chloride (PVC) or polyethylene (PE) pipe that is expanded by thermo-
forming to fit tightly to fit inside the existing, old, or host pipe.
Thermoplastic (TP): A polymer material, such as polyethylene, that will
repeatedly soften when heated and harden and reformed when cooled.
TPs are generally much easier to recycle than their thermoset (see below)
counterparts.