Apparatus and method for repairing the junction of a sewer main line and lateral pipe

An apparatus and method for repairing the junction of a sewer main line and a lateral pipe includes a generally T-shaped flexible translucent urethane inflatable bladder having a main line portion and a lateral portion. The lateral portion is inverted through the main line portion and extends out one end thereof. A liner assembly of resin absorbent material is formed, with a tubular lateral liner connected to a flat sheet main liner, at a central opening in the flat sheet liner. Each liner is coated with a polymer coating, for an airtight seal, and a polymer tape is welded to the polymer coating on the lateral liner and the junction of the lateral liner and flat sheet, to form airtight seals. The liner assembly is then installed in the bladder assembly, by threading the lateral liner into the lateral bladder until the flat sheet contacts the main line bladder. The lateral liner is then impregnated with uncured resin and the liner/bladder assembly is installed on launcher. The flat sheet liner is also impregnated with uncured resin, and the launcher is then inserted in a sewer main line and aligned with a lateral pipe to be repaired. The lateral bladder is inflated to revert the bladder upwardly into the lateral pipe forcing the liner assembly into contact with the lateral pipe, the main line sewer pipe, and the junction thereof. Once the resin is cured, the bladder assembly and launcher are removed from the sewer pipe.

TECHNICAL FIELD 
The present invention relates generally to sewer pipe line repair, and more 
particularly to an improved method and apparatus for installing a resin 
impregnated liner at the juncture of a sewer main line and lateral pipe, 
and extending down the lateral pipe. 
BACKGROUND OF THE INVENTION 
One method of repairing damaged sewer pipe is to excavate the area 
surrounding the sewer pipe and replace the broken portion. This is a very 
expensive and labor intensive solution, and is also an inconvenience to 
residents living in the area and utilizing roadways overlying the area. 
Another solution is to reline the sewer pipes on site. Such methods 
typically utilize a resin coated liner which is inserted into the existing 
sewer pipe line and fitted against the interior of the sewer pipe. The 
liner is held against the interior of the pipe while the resin cures to 
form a new pipe lining within the existing pipe. 
One example of such a method is shown in U.S. Pat. No. 4,366,012. In this 
patent, a process utilizing an elongated bladder tube having an inner 
tubular liner comprised of felt is shown. Uncured resin is introduced into 
the bladder tube and is used to impregnate the felt inner liner. The 
bladder tube and the tubular liner are then inserted into the end of the 
sewer pipe to be repaired, and moved to the area of the sewer pipe needing 
repair. Upon reaching the area of the sewer pipe needing repair, the 
impregnated felt liner is inverted out of the bladder tube so that it is 
on the outside surface of the bladder tube and is pressed against the 
interior surface of the sewer pipe. When the resin cures, a new pipe liner 
is provided at the area to be repaired. 
In many cases connection of lateral pipes to main sewer lines for 
residential or other customers was frequently accomplished by forming a 
hole in the main line with a sledge or the like. The lateral pipe was then 
simply abutted against the hole, and then the excavation back filled to 
cover the juncture. Often, this juncture of the lateral with the main line 
would leak, and would not provide a tight sealed connection. 
With the growing concern regarding the environmental impact of sewage 
leakage, such junctures are primary concern for repair, and can be 
repaired simultaneously with the lining of the lateral pipe by the method 
of the present invention. 
SUMMARY OF THE INVENTION 
It is therefore a general object of the present invention to provide an 
improved method and apparatus for repairing the juncture of a main sewer 
line with a lateral pipe. 
Another object is to provide a method and apparatus for repairing the 
juncture of a lateral with a main line which may be accomplished solely 
from the sewer main line. 
Another object is to provide an improved seal at the juncture of the 
lateral pipe to the main sewer line. 
Another object is to use a single piece T-shaped or Y-shaped liner at the 
junction between the main sewer line and the lateral pipe which provides a 
full circle seal around the interior of the main sewer line and around the 
interior of the lateral pipe. 
These and other objects of the present invention will be apparent to those 
skilled in the art. 
SUMMARY OF THE INVENTION 
The foregoing objects may be achieved by an apparatus for repairing the 
junction of a sewer main line and a lateral pipe made according to the 
present invention. The apparatus comprises a bladder assembly having an 
elongated main bladder tube and an elongated lateral bladder tube. The 
main bladder tube includes first and second opposite ends and a main 
bladder tube opening positioned therebetween. The lateral bladder tube has 
a first end connected to the main bladder tube opening and has a second 
end. 
The apparatus also includes a liner assembly formed of resin absorbent 
material and having a main liner tube and a lateral liner tube. The main 
liner tube includes a first end, a second end and a main liner tube 
opening intermediate the first and second ends. The lateral liner tube has 
a first lateral line tube end in communication with the main liner tube 
opening and is connected to the main liner tube and sealed around the main 
liner tube opening. 
The lateral bladder tube and the lateral liner tube are positioned at least 
partially within the main bladder tube, with the main liner tube being 
outside of, and surrounding the main bladder tube and being connected to 
the lateral liner tube through the main bladder tube opening. 
The lateral liner tube is invertible through the main bladder tube opening 
to an inverted position outside of the main bladder tube whereby the main 
liner tube is on the exterior of the main bladder tube and the lateral 
liner tube is on the exterior of the lateral bladder tube. 
The present invention also contemplates a method for forming a 
lateral/bladder assembly comprising forming a bladder assembly having a 
main bladder tube and a lateral bladder tube. The main bladder tube 
includes first and second opposite ends and an intermediate opening 
therebetween. The lateral bladder tube has a first end connected to the 
intermediate opening of the main bladder tube and has a second end. 
The method includes the step of inserting the lateral bladder tube inside 
the main bladder tube through the intermediate opening. Next, a liner 
assembly is formed of resin absorbent material and includes a lateral 
liner tube having a first and second end and a liner sheet having a sheet 
opening there in surrounding and attaching the first end of the lateral 
liner tube. The second end of the lateral liner tube is inserted into the 
intermediate opening of the bladder tube and is positioned at least 
partially inside the main bladder tube with the first end of the lateral 
liner tube being adjacent the intermediate opening of the main bladder 
tube, and with the liner sheet outside of the main bladder tube. The liner 
sheet is then formed into a main liner tube wrapped around and surrounding 
the main bladder tube adjacent the intermediate opening of the main 
bladder tube. 
An important feature of the present invention is the T-shaped or Y-shaped 
liner assembly. This liner assembly is constructed from a resin absorbent 
material and comprises a main liner tube and a lateral liner tube formed 
into a T-shaped or Y-shaped configuration. The single piece liner assembly 
is impregnated with an uncured resinous material capable of curing and 
hardening. The liner assembly is then positioned within the sewer main 
line pipe in a position wherein the lateral liner tube extends within the 
lateral sewer pipe and the main liner tube is within the main line sewer 
pipe. The main liner tube and the lateral liner tube are then pressed 
radially outwardly against the interior surfaces of the main line sewer 
pipe and the lateral line sewer pipe respectively. The resin is permitted 
to cure and harden to form the liner assembly into a single piece whereby 
the main liner tube provides a full circle seal around the interior of the 
main sewer pipe on both sides of the damaged junction and the lateral 
liner tube provides a full circle seal around the interior of the lateral 
sewer pipe adjacent the damaged junction.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, in which similar or corresponding parts are 
identified with the same reference numeral, and more particularly to FIG. 
1, the T-shaped bladder assembly is designated generally at 12 and forms a 
part of the liner/bladder assembly 10 shown in FIG. 4. While the bladder 
assembly 12 is shown to be T-shaped it may also be Y-shaped or otherwise 
shaped to accommodate the angle at which the main sewer pipe and lateral 
sewer pipe are disposed relative to one another. Bladder assembly 12 
includes a flat sheet 14 of translucent urethane scrim material which is 
connected to a lateral bladder tube 16 also formed of translucent urethane 
scrim material. Lateral bladder tube 16 is an elongated member having 
first and second ends 16A and 16B respectively, with the first end 16A 
attached around an opening 18 located generally centrally in flat sheet 
14. Preferably, lateral tube 16 is attached to sheet 14 by welding or the 
like to form an airtight seal at the juncture. 
Flat sheet 14 is then formed into a tube and two longitudinal side edges 
14A and 14B are welded together to form a main line bladder tube 20 (shown 
in broken lines in FIG. 1). Thus, main line bladder tube 20 and lateral 
bladder tube 16 form a T-shaped or Y-shaped bladder assembly 12 which is a 
single integral piece that is translucent. 
Referring to FIG. 2, the second end 16B of lateral bladder tube 16 is 
inverted and drawn through the main line bladder tube 20 and out a first 
end 20A of the main line bladder tube 20, such that the first end 16A of 
the lateral bladder 16 is inverted to form an opening 22 in the side wall 
of main line bladder tube 20. 
Referring now to FIG. 3, the liner assembly utilized in the liner/bladder 
assembly 10 shown in FIG. 4 is designated generally at 24. Liner assembly 
24 includes a tubular lateral liner 26 connected to a flat sheet liner 28. 
Both liners 26 and 28 are formed of felt or other resin absorbent 
material. Lateral liner 26 is formed by connected side edges of a sheet of 
liner material with a polymer coating on one side, such that the polymer 
coating 30 is on the exterior of the tube being formed. The edges of the 
sheet are sewn together at a seam 32, and a strip of polymer tape 34 is 
welded over the seam to form an airtight seal. 
Flat sheet liner 28 has a central opening formed therein, and has a polymer 
coating 36 on the top surface thereof. The lateral liner tube 26 is sewn 
to the flat sheet liner 28 around the opening, and a strip of polymer tape 
38 is then welded continuously around the juncture to form an airtight 
seal. 
Once liner assembly 24 has been completed, the second end 26B of the 
lateral liner 26 is inserted into the opening 22 in the side of main line 
bladder 20 and drawn into the lateral bladder 16 until the liner flat 
sheet 28 contacts the main line bladder 20. This step may be accomplished 
by attaching a rope (not shown) to end 26B of the lateral liner 26, and 
threading the rope through lateral bladder tube 16. Pulling the rope then 
causes the lateral liner 26 to move to the position shown in FIG. 4. 
The second end 16B of the lateral bladder is closed off by inserting plug 
15 which is held in place by a clamp 17. Extending through plug 15 are a 
PVC air pipe 21 and wick 40, as shown in FIGS. 4 and 5. Vacuum opening 19 
is provided in the end 16B of bladder tube 16. 
A quantity of curable resin 42 in liquid form is then introduced into the 
opening 44 of flat sheet liner 28 so as to continue into the lateral liner 
26 within lateral bladder 16 (shown in FIG. 5). A vacuum source (not 
shown) is connected over the vacuum opening 19 to collapse the walls of 
the lateral bladder 16 and lateral liner 26 as shown in FIG. 6. The wick 
40 will provide a path for evacuating gas from the lateral bladder 16 
until the curable resin moves to the down stream end 16B of lateral liner 
16 and completely impregnates the liner. Because the bladder assembly 12 
is formed of a translucent material, it is possible to visually verify 
that the lateral liner 26 is completely impregnated with resin while 
inside the lateral bladder 16. A roller 46 is preferably utilized to move 
the slug of resin and assist in impregnating the liner 26 with the resin 
material. 
Referring now to FIGS. 7 and 8, the liner/bladder assembly 10 is loaded 
into a launcher 48 for installation into a sewer pipe. Launcher 48 
includes a hollow cylindrical tube 50 having forward and rearward ends 50A 
and 50B respectively. An aperture 52 is formed generally through the side 
wall of the launcher tube 50. The left hand edge of aperture 52 is 
provided with an upwardly extending flange 70 which facilitates the 
sliding of lateral bladder tube 16 into the launcher tube 50. The right 
side of the aperture 52 is provided with a downwardly curved wall 72 (FIG. 
12). 
Launcher 50 includes a clevis 80 mounted adjacent its rear end. Surrounding 
the rear end 50B of launcher 50 is a ring bearing 82, and mounted to ring 
bearing 82 are a pair of wheels 84 located at the 5 o'clock and 7 o'clock 
positions when viewed from an end view (not shown). The ring bearing 82 
permits the wheels 84 to remain stationary while the entire body of the 
launcher 50 can be rotated about its longitudinal axis. Protruding 
outwardly from the surface of launcher tube 50 adjacent the rear end 50B 
are a pair of clamping ribs 86. Similarly a clamping rib 86 is provided 
adjacent the forward end 50A. A circular ring bearing 88 is also provided 
adjacent the forward end 50a and includes a pair of wheels 90 mounted 
thereon. 
Liner/bladder assembly 10 is installed on the launcher 48 by inserting the 
second end 16B of lateral bladder 16 through aperture 52 and through 
launcher tube 50 and out the forward end 50A of the launcher tube 50. As 
the main line bladder tube 20 approaches the launcher 48, the rearward end 
50B of the launcher tube 50 is inserted into the first end 20A of the main 
line bladder tube 20, as shown in FIG. 8. The flat sheet liner 28 is moved 
over the launcher side wall aperture 52, with the main line bladder 20 
extending on opposite sides of aperture 58. 
As shown in FIGS. 9-11, the ends 20A, 20B of the main line bladder tube 20 
are attached to the forward and rearward ends 50A and 50B of launcher tube 
50 by bands 54, and the launcher tube is connected to a support frame 56 
which holds the launcher 48 in the air. A collapsible hose 68 is clamped 
to the forward end 50a of launcher tube 50 by means of a clamp 92. 
A two piece platform 58 is pivoted up into position to support the flat 
sheet liner 28 above the launcher 48. As shown in FIG. 10, the two piece 
platform 58 includes two halves 58A and 58B with semicircular holes 60A 
and 60B which will form an aperture through which the lateral lining will 
extend when the platform is moved to the support position shown in FIG. 9. 
Uncured resin 42 is then poured onto the flat sheet liner 28 and worked 
into the liner material. The two piece platform 58 is then separated and 
lowered, as shown in FIG. 10, and the flat sheet liner 28 is wrapped 
around the main line bladder 20, with one side edge 28A overlapping the 
other side edge 28B, as shown in FIG. 11. Side edges 28A and 28B are 
temporarily held tightly together with straps 60 of hook and loop 
fastener, tape, rubber bands, or other similar fasteners. 
A positioning robot 62 is then attached to the rearward end 50b of launcher 
tube 50, as shown in FIG. 12 and is used to introduce the launcher 48 and 
liner/bladder assembly 10 into the sewer main line 64. Wheels 84, 90 
facilitate movement of assembly 10 within the main sewer line 64. The 
lateral liner opening 44 is aligned with the lateral pipe 66 to be 
repaired. Bearings 82, 88 permit the robot 62 to rotate assembly 10 a full 
360.degree. so as to obtain alignment. Robot 62 also is capable of 
extending or retracting to move assembly 10 up to six inches for final 
exact alignment. 
Once positioned, air pressure is applied within the launcher tube 50 via a 
"lay flat" tube 68 connected to the forward end 50a of launcher tube 50, 
to inflate the lateral bladder 16 and invert the lateral bladder upwardly 
into lateral pipe 66. The air pressure also presses the main liner 20 
radially outwardly against main sewer line 64 and presses lateral liner 26 
radially outwardly against lateral pipe 66 until the resin impregnated in 
the lateral liner 26 and main line liner 28 cures. Once cured, the 
generally T-shaped or Y-shaped liner assembly 24 is a one piece liner 
connecting the main pipe 64 with the lateral pipe 66 to seal them 
together. It provides full circle sealing of both the lateral pipe 66 and 
the main pipe 64. Because of the use of the polymer coated liner assembly 
24, the actual liner assembly can be tested prior to installation in the 
ground, to ensure an airtight connection. 
Whereas the invention has been shown and described in connection with the 
preferred embodiment thereof, many modifications, substitutions and 
additions may be made which are within the intended broad scope of the 
appended claims.