Page 90 - Trenchless Technology Piping Installation and Inspection

Existing Pipeline Renewal and Replacement Methods 57

Existing pipeline
problems

Recurrent
Localized Extensive
localized
problems problems
problems
Is increase Yes
in flow capacity
necessary?

No

Is reduction of Would renewal
No Yes
flow capacity reduce flow
permissible? capacity?
No
Yes
Is renewal No
technically
possible?
Yes
Is
replacement Yes Are there No
economically other limitations for
justifiable? replacement?
No Yes
Localized Renewal Replacement
repairs
FIGURE 2.4 Decision support system for selection of a trenchless renewal,
replacement or repair methods.

2.3.3 Modified Sliplining
Modified sliplining (MSL) includes methods in which pipe sec-
tions or plastic strips are installed in close-fit inside existing pipe
and the annular space is grouted. There are two variations of modi-
fied sliplining method: panel lining (PL), and spiral wound process
(SWP).
Panel linings can be used to structurally renew large-diameter
(more than 48 in. or worker-entry) pipes. This method can accommo-
date different shapes, such as noncircular pipelines. The main type of
material for this method is fiberglass. Figure 2.7 presents a panel
lining method.