Reinforced lining hose for softlining pipe rehabilitation

An improved tubular lining hose for use in softlining pipe rehabilitation which includes the novel use of a layer of reinforcing fibers to reinforce the lining hose. In a preferred embodiment, a layer of reinforcing fibers, such as fiberglass, is encapsulated between layers of resin absorbing material saturated with resin. The saturated resin absorbing layers form a protective veil around the reinforcing fibers and protect the reinforcing fibers from water and other corrosive materials.

BACKGROUND OF THE INVENTION 
The present invention relates to an improved lining hose for use in methods 
of rehabilitating a pipe conduit which is in a damaged or deteriorated 
state. More particularly, the present invention relates to an improved 
lining hose for use in softlining pipe rehabilitation methods wherein the 
lining hose is saturated with curable resin, introduced into a pipe 
conduit and shaped to conformingly line the pipe conduit where it is cured 
in place so as to form a rigid liner. 
Various methods of rehabilitating a pipe conduit which is buried 
underground are known in the art. Generally speaking, such methods include 
the use of a liner having a diameter which is substantially the same as 
the inner diameter of the pipe conduit to be rehabilitated. The liner 
frequently includes an impermeable layer and an adjacent resin-absorbing 
layer. This resin-absorbing layer is impregnated with a liquid resin prior 
to the introduction of the thus treated liner into the pipe conduit. After 
being properly positioned in the pipe conduit, the liner is pressed 
against the inner surface of the pipe conduit by fluid pressure. 
One such method of lining a pipe is disclosed in U.S. Pat. No. 4,009,063 
which discloses a liner comprising a non-woven felt sandwiched between an 
outer membrane and an inner membrane of plastic sheet material. The 
non-woven felt material is impregnated with an uncured thermosetting 
resin. The resin is cured while the liner is held against the inner 
surface of the pipe conduit so as to form a rigid self-supporting liner. 
The alleged purpose of this impermeable outer layer is to avoid the need 
for cleaning the pipe conduit prior to installation of the liner. 
Another method of lining a conduit is disclosed in U.S. Pat. No. 4,064,211. 
This method utilizes a liner having a resin impregnated inner layer and an 
impermeable layer outwardly bonded to and surrounding the inner layer. 
This liner is introduced into the interior of the pipe conduit by turning 
over one end region of the liner and causing the turned over region to 
gradually advance into the interior of the pipe conduit using an inversion 
process. During this inversion process, the resin impregnated layer is 
gradually transferred to the exterior of the lining hose by fluid 
pressure. The resin impregnated layer will contact the inner surface of 
the pipe conduit. In order to eliminate friction, the liner, before being 
turned inside out, is supported buoyantly by liquid which serves to carry 
the liner. 
U.S. Pat. No. 4,770,562 discloses a method for rehabilitating a conduit 
using a lining hose having an outer impermeable layer surrounding and 
adjacent to an inner resin-absorbent layer. The resin-absorbent layer is 
saturated with an excess volume of resin. The outer impermeable layer is 
then perforated to form a plurality of flowthrough openings for the resin. 
The lining hose is subsequently introduced in a collapsed state into the 
pipe conduit, and the lining hose is shaped to conformingly line the pipe 
conduit. The shaping of the lining hose is accomplished by everting an 
auxiliary hose, also known as a calibration hose, inside the lining hose. 
The eversion of the calibration hose inside the lining hose will force the 
excess amount of resin through the flowthrough openings and into contact 
with the inner surface of the pipe conduit. The excess resin will also 
fill existing cracks and fissures in the conduit. A variation of the liner 
described in the U.S. Pat. No. 4,770,562 includes a relatively thin layer 
of resin-absorbent material outwardly adjacent to the impermeable surface. 
This thin layer of resin-absorbent material facilitates the spreading of 
the excess resin once the impermeable layer has been perforated and the 
shaping of the lining hose process has begun. 
As previously stated, most liners in softlining applications utilize a 
layer of nonwoven felt for the resin absorbing layer of the lining hose. 
One of the purposes of the felt is to provide support for the uncured 
resin of the impregnated lining hose. The felt serves as a reservoir 
and/or carrier means for the uncured resin. Once cured, the resin provides 
the structural strength of the liner. The layer of felt is actually a 
deterrent to the strength of the liner after the resin has cured since it 
occupies space that could otherwise be filled with resin. 
In the past, practitioners in the softlining industry have also utilized a 
layer of fiberglass for the resin absorbent member of the lining hose. 
U.S. Pat. 4,770,562 teaches such a use. A fiberglass mat provides greater 
structural strength for both the uncured and cured liner than does a mat 
of nonwoven felt. Despite its superior strength characteristics, 
fiberglass has not replaced felt as the preferred medium for the resin 
absorbing layer due to the wicking problems associated with fiberglass. 
Fiberglass fibers have a high resistance to stretching. The resin in a 
cured-in-place liner bonds or adheres to fiberglass fibers upon curing. 
Due to the bond between the resin and the fiberglass fibers, the resin 
also becomes more resistant to stretching when axial or radial loads are 
applied to the cured liner. Thus, the cured resin is reinforced by 
fiberglass so long as the bond between the resin and fiberglass is not 
broken. 
Cured-in-place liners are typically installed in environments that are 
continuously exposed to water and other corrosive materials. 
Cured-in-place liners are also exposed to varying temperatures and flow 
conditions. The bond between the fiberglass and cured resin is subject to 
constant stress and strain due to the different coefficients of expansion 
of resin and fiberglass. Over time, the repeated expansion and contraction 
of the resin and fiberglass, caused by the varying temperature and flow 
conditions, will create tiny spaces between the resin and the fiberglass 
fibers. 
With conventional cured-in-place liners using fiberglass, the fiberglass 
fibers located on the inner and outer surfaces of the liner are exposed to 
the water and other corrosive materials. Due to capillary or wicking 
action, the water and other corrosive materials are absorbed into the tiny 
spaces adjacent to the exposed fiberglass fibers. The absorption of water 
and other corrosive materials enhances the expansion and contraction of 
the resin and fiberglass, thereby further deteriorating the bond between 
the resin and fiberglass. Corrosive reactions with the resin/fiberglass 
laminant also exacerbates the deterioration of the bond between the resin 
and fiberglass. As a result of the wicking action, the space between the 
resin and fiberglass fibers becomes progressively larger and larger. In 
addition, as the space between the resin and a given fiber grows in size 
and length, previously unexposed fiberglass fibers adjacent to the exposed 
fibers become exposed to the water and other corrosive materials. Over 
time, the wicking of water and other corrosive materials into the laminant 
will destroy the bond between the resin and the fiberglass fibers. When 
this occurs, the reinforcing effects of the fiberglass is lost causing the 
liner to lose much of its structural strength, thereby ending the useful 
life of the liner prematurely. 
Other reinforcing materials, such as Kevlar.TM. and carbon fibers, may be 
used as substitutes for nonwoven felt. However, these materials may also 
experience the problems associated with fiberglass when exposed to water 
and other corrosive materials. 
The present invention overcomes the wicking problems associated with the 
use of fiberglass and other reinforcing fibers. The lining hose of a 
preferred embodiment of the present invention sandwiches a layer of 
fiberglass, or other desirable reinforcing fiber, between an inner and 
outer layer of resin absorbent material. The resin absorbent material, 
such as nonwoven felt, is saturated with curable resin. Upon curing, the 
resin in the inner and outer resin absorbent layers encapsulate the 
fiberglass layer and protects it from water and other corrosive materials. 
Thus, the resin absorbent material acts as a protective veil surrounding 
the layer of reinforcing fiber. Wicking problems are virtually eliminated 
because the reinforcing fibers are not exposed to water or other corrosive 
materials. 
SUMMARY OF THE INVENTION 
The present invention relates to an improved tubular lining hose for lining 
a pipe. More particularly, the improved tubular lining hose is used in 
softlining pipe rehabilitation. The lining hose includes the novel use of 
a layer of reinforcing fibers to reinforce the lining hose. In a preferred 
embodiment of the present invention, a layer of reinforcing fibers is 
positioned between an inner and outer layer of resin-absorbing material. 
The resin-absorbing material is saturated in curable resin prior to 
installation of the tubular liner. The resin from the inner and outer 
resin-absorbing layers encapsulates the layer of synthetic fibers, thereby 
protecting the layer of synthetic fibers from water and other corrosive 
materials. 
The layer of fiberglass, or other desirable reinforcing fibers, adds 
increased strength characteristics to both the uncured and cured liner. As 
a result of the increased strength, longer sections of pipe may be lined. 
In addition, a cured liner of the present invention can be configured to 
withstand greater external and internal loads than conventional 
cured-in-place liners. As a result of its increased strength, the 
reinforced lining hose of the present invention requires less resin 
absorbent material and less resin to fully saturate the lining hose than 
conventional cured-in-place liners. Thus, the improved lining hose 
requires less materials to produce a stronger final product. In addition, 
the improved lining hose reduces the amount of curing time, and thus saves 
additional monies, due to the smaller volume of resin being cured. 
Another feature of the present invention is that the orientation of the 
fiberglass or other reinforcing fibers may be arranged to meet the 
reinforcing requirements of a particular job. 
In a preferred embodiment, a fiberglass mat is encapsulated between layers 
of nonwoven, polyester felt. Other embodiments of the present invention 
use a mat of Kevlar.TM. fibers, or a mat of carbon fibers, encapsulated 
between layers of nonwoven polyester felt. Other materials may be used for 
the layer of reinforcing fibers so long as the layer of reinforcing fibers 
has greater tensile and/or radial strength than the adjacent 
resin-absorbing material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A preferred embodiment of the lining hose of the present invention is 
illustrated in FIG. 1. A lining hose 1 is shown having an inner layer of 
resin absorbing material 2. Outwardly adjacent to the inner layer 2 is a 
layer of reinforcing fibers 3. An outer layer of resin absorbing material 
4 is outwardly adjacent to the layer of reinforcing fibers 3. Outer 
covering layer 5 is outwardly adjacent to the outer resin absorbing layer 
4. The lining hose 1 may be made, for example, of an inner and outer layer 
of resin absorbent material consisting of a nonwoven fibrous material such 
as polyester needled felt. The layer of reinforcing fibers 3 may consist 
of a mesh or mat of fiberglass. The outer covering layer 5 generally is a 
synthetic plastic material such as polyurethane which is impermeable to 
fluid. The outer covering layer 5 is fixedly attached to the resin 
absorbent outer layer 4 by adhesion, extrusion or other appropriate 
methods known in the industry. 
By way of example, lining hose 1 may have an inner layer of resin absorbing 
material 2 comprising a layer of nonwoven polyester felt of 2-8 mm in 
thickness. The layer of reinforcing fibers 3 may comprise a relatively 
thin, up to 2 mm thick, mesh of fiberglass fibers. The outer layer of 
resin absorbing material 4 may comprise a 2-8 mm thick layer of nonwoven 
polyester felt. Other embodiments may have layers of varying thickness. 
The thickness of the various layers will depend upon such factors as the 
size, length and depth of a given pipe to be lined. An impermeable film of 
plastic material would comprise the outer covering layer 5. Examples of 
the plastic material use for the impermeable outer covering layer 5 
include polyurethane, polypropylene and polyethylene. 
The outer felt layer may be attached to the fiberglass mesh and inner felt 
layer by lightly flame bonding the inside surface of the outer felt layer 
to the outside surface of the inner felt layer. The fiberglass mesh is 
sufficiently porous so that polyester fibers from the inner and outer 
layers of felt protrude through the fiberglass mesh. The light flame 
bonding process sufficiently fuses the polyester fibers of the inner and 
outer felt layers that protrude through the fiberglass mesh together so 
that the reinforcing fiberglass mesh is sandwiched between the felt 
layers. The light flame bonding process does not destroy the permeability 
of the inner and outer felt layers and the layer of reinforcing fibers. 
Thus, when saturated with resin, the inner and outer felt layers form a 
protective veil around the reinforcing fiberglass mesh such that the 
latter is protected from water and other corrosive materials. 
Alternative methods of constructing the reinforced lining hose of the 
embodiment include stitching the layer of reinforcing fibers to the resin 
absorbent layers or using a combination of stitching and light flame 
bonding techniques to position the reinforcing fibers between the resin 
absorbing materials. Other techniques for constructing the reinforced 
lining hose will be apparent to those of skill in the art. 
As shown in FIG. 1, reinforcing layer 3 is composed of reinforcing fibers 
oriented with a substantially equal number of fibers running 
longitudinally and radially to the axis of the hose. Longitudinal fibers 
31 are generally parallel to the longitudinal axis of lining hose 1. 
Radial fibers 32 are generally radial to the longitudinal axis of lining 
hose 1. Such an embodiment generally provides both radial and longitudinal 
reinforcement to the lining hose. Such an orientation improves the 
strength of the lining hose for internal radial loads, external radial 
loads, and longitudinal loads while limiting stretch in all directions. 
Such an orientation would provide increased strength for: lining long 
sections of pipe having few, if any, service lines; lining deep pipes 
exposed to high internal and external loads; lining badly deteriorated 
pipes that have large sections of the pipe wall missing; and lining some 
pressure pipes. 
FIGS. 2, 3 and 4 show alternative orientations of the reinforcing fibers of 
the reinforcing layer 3. FIG. 2 illustrates a layer of reinforcing fibers 
that are orientedpredominantly parallel to the longitudinal axis of the 
lining hose. The radial or latitudinal fibers 34 are included mainly for 
handling purposes of the mat or mesh. Such an arrangement of predominantly 
longitudinal fibers, shown as 33, will increase the longitudinal strength 
of the liner. Thus, this embodiment will allow longer sections of lining 
hose to be pulled within a pipe. Such an arrangement of predominantly 
longitudinal fibers will limit the longitudinal stretch of the lining hose 
to virtually zero while allowing radial stretching of the hose. The radial 
stretching permitted by this embodiment of the reinforcing layer 3A, will 
allow dimpling to occur at service connections for easy identification of 
the same. 
FIG. 3 illustrates the reinforcing layer 3B whereby the reinforcing fibers 
are arranged in a cross-hatched manner diagonally about the longitudinal 
axis of the lining hose. Such an arrangement provides the most 
reinforcement for internal and external radial loads in the cured liner as 
compared with the embodiments shown in FIGS. 1 and 2. However, the 
diagonal arrangement depicted in FIG. 3 does not provide as much 
longitudinal reinforcement for use during pull-in and for limiting 
longitudinal stretch as do the embodiments shown in FIGS. 1 and 2. The 
cross-hatched embodiment shown in FIG. 3 also allows radial stretching of 
the lining hose. 
FIG. 4 illustrates the reinforcing layer 3C whereby the reinforcing fibers 
are, in general, randomly oriented about the longitudinal axis of the 
lining hose. Reinforcing layer 3C includes layers of randomly oriented 
fibers 40 overlaying a cross-hatched stitching 42, designed to hold the 
randomly oriented fibers together as a mat. Cross-hatched stitching 42 may 
resemble the general pattern of layer 3 of FIG. 1 or layer 3B of FIG. 3 or 
any other desirable pattern that is effective to form a base for the 
overlying randomly oriented fibers. The mat of randomly oriented fibers 
are also referred to in the industry as a chopped strand mat. The layer of 
randomly oriented fibers 40 is generally denser than illustrated in FIG. 
4. A chopped strand mat of reinforcing fibers will increase the radial 
strength of a cured liner. Accordingly, this embodiment is well suited for 
use in pressure pipes. 
Other embodiments of the present invention may utilize a combination of the 
fiber orientations illustrated in FIGS. 1-4 so that a lining hose may be 
custom designed to meet the particular needs of any given job. For 
example, the embodiment illustrated in FIG. 2 may be combined with the 
embodiment shown in FIG. 1 so that the layer of reinforcing fibers 3A is 
located in the lining hose opposite service connections in the pipe to be 
lined. The remaining layer of reinforcing fibers would be oriented as 
shown in FIG. 1. This combination would allow easy identification of 
service connections to be reopened by a mechanical cutter while providing 
reinforcement for axial loads. 
Other embodiments of the present invention may utilize Kevlar.TM. or carbon 
fibers for the layer of reinforcing fibers. Kevlar.TM. is the trademark 
for an aromatic polyamide fiber of extremely high tensile strength and 
greater resistance to elongation than steel. Other materials may be used 
for the layer of reinforcing fibers so long as the layer of reinforcing 
fibers 3 has greater tensile and/or radial strength than the inner and 
outer layers of resin absorbing material 2 and 4, respectively. In 
addition, the layer of reinforcing fibers may be comprised of a 
combination of different reinforcing fibers. 
Various methods for installing a lining hose are known in the art. One such 
method is illustrated in FIGS. 5 and 6. Referring to FIG. 5, pipe conduit 
11 is buried underground and is provided with control shafts or manholes 
12 which lead to the surface. In FIGS. 5 and 6 there is illustrated a 
section of the pipe conduit which is situated between the two control 
shafts. The pipe conduit generally is in a deteriorated shape and may 
include a plurality of cracks or fissures as illustrated by the numeral 
13. 
A lining hose 1 is shown to be already received in the interior of the 
section of the pipe conduit 11 which is situated between the two 
aforementioned control shafts 12 having been pulled into the illustrated 
position in its flattened or collapsed state by means of a rope or cable 
15 and a non-illustrated winch. The rope or cable 15 is secured to one end 
of the lining hose 1 by pulling member 16 as illustrated in FIG. 5. The 
pulling of the lining hose into the pipe section is generally known in the 
art. 
Prior to inserting the lining hose into the conduit to be lined, the resin 
absorbent material of lining hose 1 is soaked with a volume of resin that 
exceeds the volume required to totally saturate the inner and outer layers 
of resin absorbent material, layers 2 and 4 respectively. The inner and 
outer layers of resin absorbent material may be saturated with resin using 
vacuum impregnation or injection methods that are commonly known in the 
art. The lining hose 1 must be saturated with a sufficient volume of resin 
so that the layer of reinforcing fibers 3 as shown in FIG. 1, is 
encapsulated in resin during both the uncured and cured stages of 
installation. 
The introduction of resin may be performed directly at the installation 
site or it may be accomplished at an appropriate off-site location. After 
the volume of resin has been introduced into the lining hose, the outer 
covering layer 5 is perforated so as to provide the outer covering layer 
with flowthrough openings 20 as illustrated in FIG. 1. The perforating of 
the lining hose may also be performed at the installation site or it may 
be performed off-site. Methods of perforating the lining hose are known in 
the art. 
The resin soaked lining hose is flexible enough to be pulled into the 
conduit in a collapsed position. The lining hose will later be expanded to 
substantially the inner diameter of the conduit to be lined. Accordingly, 
the lining hose 1 is constructed to have substantially the same diameter 
as the inner diameter of the pipe conduit to be lined. Due to its flexible 
nature, the lining hose may be installed through the existing control 
shaft 12 with little or no excavation work. 
The collapsed lining hose 1 of FIG. 5 is shaped to conformingly line pipe 
conduit by introducing a calibration hose 22 into the lining hose. One 
method of introducing a calibration hose 22 into the lining hose 1 
situated in the above-mentioned section of the pipe conduit 11 is 
illustrated in FIG. 6 of the drawings. An inversion pipe 23, which has the 
configuration of a tubular elbow, is inserted into the proximal control 
shaft 12 as shown in FIG. 6. The length of the inversion pipe will vary in 
order to accommodate the height or depth of the control shaft 12. The 
forward most free end of the calibration hose 22 and the associated end of 
the lining hose 1 are attached to the horizontally extending portion of 
inversion pipe 23. Before attaching the calibration hose to the inversion 
pipe, the forward end is turned over outwardly. The turned over portion of 
the calibration hose and the associated end of the lining hose may be 
attached to the inversion pipe 23 by use of steel bands or other 
appropriate means. Construction of the calibration hose 22 is commonly 
known in the art. 
Initially, only the connecting end of the calibration hose 22 is turned 
over outwardly. As a result of the introduction of fluid into the 
inversion pipe 23, and in dependence on the attendant pressure buildup, 
the calibration hose 22 is expanded by the fluid entering the same from 
the inversion pipe 23 and, at the same time, the region of turning over of 
the calibration hose 22 becomes gradually and progressively displaced away 
from the region of attachment of the lining hose 1 and calibration hose 22 
to the inversion pipe 23. To maintain a constant fluid pressure, it is 
merely necessary to maintain the height of the fluid column contained in 
the inversion pipe 23 constant. As the fluid pressure everts the 
calibration hose, the lining hose 1 is expanded, shaped and pressed 
against the internal surface of the pipe conduit 11. 
The fluid pressure exerted on the calibration hose forces the excess resin 
through the flowthrough openings 20 of the outer covering layer 5 of the 
lining hose. The excess resin which passes through the flowthrough 
openings 20 of the outer covering layer 5 of the lining hose will bond the 
lining hose 1 to the internal surface of the conduit 11. Any remaining 
excess resin will flow into the cracks or fissures 13 of the conduit. 
After the lining hose 1 has been fully shaped and expanded to the internal 
diameter of the pipe conduit, the resin is cured. The curing process may 
be accelerated by heating the fluid used to evert the calibration hose. 
Methods of accelerating the cure of the resin by heating the fluid are 
known in the art. After curing, the lining hose 1 forms a rigid liner 
which is rigidly connected to the original pipe conduit 11. Examples of 
suitable resins include polyester, vinylester, epoxy and other curable 
resins. 
The lining hose described above is installed in a pipe using the method 
generally described in U.S. Pat. No. 4,770,562. Other embodiments of a 
lining hose utilizing the present invention may be installed in a pipe by 
alternative methods known in the softlining industry. The lining hose may 
include an outer covering layer 5 that is not perforated. Alternatively, 
the lining hose may include a protective inner covering layer, such as a 
film of polyurethane, inwardly adjacent to the inner layer of resin 
absorbing material 2. 
In another embodiment of the present invention, the lining hose may include 
an additional resin-absorbent material externally and outwardly adjacent 
to the outer covering layer 5. This third layer of resin-absorbent 
material provides a passageway for distributing the excess resin that is 
forced through the flowthrough openings 20 in outer covering layer 5. The 
third layer of resin-absorbent layer may be a thin layer of non-woven 
material, such as needled polyester felt, which will facilitate the 
uniform distribution of the excess resin which flows through the 
flowthrough openings 20 around the exterior of the lining hose. It is 
important in such an embodiment to saturate the lining hose with a volume 
of resin that exceeds the volume required to totally saturate the inner 
and outer layers of resin absorbing material, 2 and 4 respectively. This 
ensures that the reinforcing fibers are totally encapsulated in resin, 
thereby protecting the reinforcing fibers from water and other corrosive 
materials. 
In addition to the embodiments described above, the reinforced lining hose 
of the present invention may have only one resin-absorbent layer adjacent 
the layer of reinforcing fibers. Such an embodiment would be used in 
environments where only one side of the liner is exposed to water and 
other corrosive materials. In such a situation, the resin absorbent layer 
is positioned between the layer of reinforcing fibers and the water and 
other corrosive materials so that the resin in the resin absorbent layer 
forms a protective shield around the reinforcing fibers. Therefore, the 
reinforcing fibers are not exposed to water and other corrosive materials. 
Thus, the resin-absorbent layer will be either inwardly or outwardly 
adjacent the layer of reinforcing fibers depending on the location of the 
anticipated water and other corrosive materials, i.e., whether the water 
and other corrosive materials will be contacting the inside or the outside 
of the liner. 
It will be understood by those skilled in the art that certain variations 
and modifications can be made without departing from the spirit and scope 
of the invention as defined herein and in the appended claims.