Page 475 - Trenchless Technology Piping Installation and Inspection

Glossary of Terms 425

Jacking: The actual pushing of pipe or casing in an excavated hole. This
is usually done with hydraulic cylinders (jacks), but has been done with
mechanical jacks and air jacks.

Jacking force: Force applied to pipes in a pipe jacking operation.
Jacking frame: A structural component that houses the hydraulic
cylinders used to propel the microtunneling machine and pipeline. The
jacking frame serves to distribute the thrust load to the pipeline and the
reaction load to the shaft wall or thrust wall.
Jacking pipes: Pipes sections with smooth outside joints designed to be
installed using pipe jacking techniques.
Jacking pit: See jacking shaft.

Jacking shaft (also launch or entry shaft): Excavation from which trenchless
technology equipment is launched for the installation or renewal of a
pipeline.
Jacking shield: A steel cylinder from within which the excavation is
carried out either by hand or machine. Incorporated within the shield are
facilities to allow it to be adjusted to control line and grade.
Joint sealing: Method in which an inflatable packer is inserted into a
pipeline to span a leaking joint, resin, or grout being injected until the
joint is sealed and the packer then removed.
Lateral: A service line that transports wastewater from individual
buildings to a main sewer line.
Lateral connection: The point at which the downstream end of a building
drain or sewer connects into a larger-diameter sewer.
Launch pit: See drive shaft or pit.
Lead pipe: The leading pipe designed to fit the rear of a jacking shield
and over which the trailing end of the shield is fitted.
Light cure: The curing of a CIPP liner using UV light energy in lieu of
either water or steam.
Liner: A fabric tube that has been saturated with a liquid resin.
Liner plate: A proprietary product, used to line tunnels instead of casing,
and comes in formed steel segments. When these segments are bolted
together they form a structural tube to protect the tunnel from collapsing.
The segments are made so that they may be bolted together from inside
the tunnel.
Lining: A renewal process where a new pipe or coating material is
inserted or cured in place to give an existing pipe a new design life.

Localized (spot) repair: Repair work on an existing pipe, to an extent less
than the run between two access points or manholes.