Figure 2-24.—Resin temperature vs kick-over time.
Application of Plastic Patches
In the following discussion on applying different
types of plastic patches (simple, elbow, severed, and
others) you can readily see that as the individual patch
materials are applied, the patch becomes progressively
wider. The sketch in figure 2-25 shows the relative
positions of the patch materials to one another. The
buildup in the patch length during application must be
considered in initially determining the length of the
patch to be applied. Where suitable, allow the patch to
extend at least 4 to 5 inches on either side of the
rupture.
In addition to the size of the rupture, the width of
the patch also may depend upon the location of the
rupture in the pipe system. For example, an elbow
rupture may require a patch of greater width than the
same size rupture would require in a straight section
of pipe. Complete application instructions are in-
cluded in each kit.
Figure 2-25.—Sequence of applied patch materials.
PREPARATION.— Before you actually apply
the plastic patch, you must make the following prepa-
rations:
1. Secure or isolate the ruptured area in the piping
system.
2. Remove all lagging.
3. Clean the area around the rupture and remove
all grease, oil, dirt, paint, and other foreign matter. If
grease or oil is present, use an approved solvent to clean
around the rupture. If no approved solvent is available,
scrape and wipe the surface until it is clean. When a
clean surface is obtained, the surface may be further
abraded for better adhesion. An abrasive cloth is fur-
nished with the kit.
4. Ensure that all moisture and fuel are removed
from the inside of the piping and the entire pipe surface
is dry.
5. Where practical, the rupture should be simpli-
fied by bending or removing irregular projections. This
may be done by cutting or burring.
CAUTION
Ensure no explosive conditions exist be-
fore you use spark-producing tools or burring
equipment.
6. Determine the amount of materials required,
such as the amount of woven roving cloth as well as the
2-17
