Method of making leakproof sites of entry of domestic connector pipes and similar feed pipes into sewers

A method for producing leak-proof sites of entry for domestic connection pipes and other feed pipes into sewers. The method includes the steps of widening the site of entry of the feed pipe into the sewer, providing a barrier towards the interior of the sewer at the site of entry, providing a barrier within the feed pipe at a predetermined distance from the site of entry, introducing an expanding solidifying sealing mass into the space between the barriers so as to fill the space and any openings, fissures, or cracks found therein, clearing a path of flow from the feed pipe through the sealing mass and into the sewer, and optionally lining the flow path with a solidifying, insoluble, corrosion-resistant and non-ageing material.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates generally to construction, repair and modification of 
waste water drainage systems, and more particularly, to a method of making 
leak-proof sites of entry for domestic connection pipes and other feed 
pipes into waste water drainage systems. 
2. Description of the Related Art 
When constructing and renovating waste water drainage systems (e.g. 
sewers), it is very important that the sites of entry of feed pipes into a 
drainage system be leak-proof because leaking sewage can contaminate 
groundwater. Unfortunately, it is often very difficult to construct a 
leak-proof site of entry. For example, poor accessibility to the site of 
entry is a common problem in repairing or modifying a waste water drainage 
system. In most instances, drainage systems into which feed pipes enter, 
are not man-sized and generally are located below narrow streets with high 
traffic density. Traditional methods of repairing a drainage system or 
modifying a drainage system require excavating the area around the site of 
entry. The relatively high monetary costs of such earthwork are often 
increased by expenditures caused by traffic requirements, such as the 
provision of detours. Therefore, a need exists for a method to construct, 
repair and modify waste water drainage systems that avoids the costs 
associated with excavating the area around the site of entry and more 
importantly, provides a leak-proof site of entry that eliminates 
groundwater contamination from leaking sewage. 
Various methods of making sites of entry of feed pipes into sewers have 
already been suggested. However, these methods insufficiently meet the 
object of providing well sealed sites of entry of the type discussed 
herein. For example, according to DE-A-37 00 883, in man-sized sewers 
which are provided with a lining made of bent plate elements, a hose-like, 
mortar-filled collar surrounding the site of entry is inserted between the 
sewer wall and the lining to form a leak-proof site of entry. The 
insertion of such a collar is hardly feasible if the sewer is not 
man-sized. Furthermore, it must be taken into account that the mortar 
filling of this hose-like collar will not permit this collar to snugly fit 
around all sealing sites, and thus leaks may still occur. 
In EP-A1-403 773, annular or hose-shaped seals are provided between the 
inner pipe and the sewer wall at a site of entry of a lateral feed pipe in 
a sewer renovated with an inner pipe to avoid the penetration of 
waste-water coming from the feed pipe into the gap present between the 
sewer wall and the inner pipe. The insertion of such seals is difficult, 
and this technique requires that the pipe forming the lateral connection 
is fitted sufficiently leak-proof in the sewer wall. If such a leak-proof 
fit is not ensured, waste-water can leak into the surrounding soil. 
EP-A1-350 802 describes a technique which provides for the insertion of an 
inner pipe into a main train of sewer pipes when renovating pipings into 
which feed ducts, e.g. from domestic connections, enter laterally, with 
the annular space formed between the original pipe wall and the inner pipe 
being filled with a mortar mass. At the sites of entry, apertures are 
formed starting from the interior of the inserted inner pipe by cutting 
through the wall of the inner pipe and the mortar layer, thereby forming a 
flow connection between the sites of entry and the main train of pipes. As 
a rule, the connection of the feed ducts with the main train of pipes 
remains in its original state and will not be changed even if moderate 
eccentricities occur when cutting out the apertures. Further, spraying a 
thin layer of artificial resin at the side faces of the transition may be 
considered. A thorough elimination of possible faults in the attachment of 
the feed ducts to the main train of pipes, however, is not provided for by 
this technique. 
According to a further technique which is described in U.S. Pat. No. 
4,728,223, after insertion of an inner pipe into the main train of pipes, 
apertures are cut into this inner pipe at those sites where the feed ducts 
enter into the main train of pipes. A filling element is then inserted 
into the feed ducts at the site of entry. This filling element projects 
into the interior of an inner pipe introduced into the main train of 
pipes. The filling element then places filler in the annular space between 
the inner pipe and the wall of the main train of pipes. However, treatment 
of the site of connection of the feed pipes with the main train of pipes 
which would repair any damage present in this region is not provided for 
by the technique. 
Finally, a technique for renovating old sewers by inserting new inner pipes 
of synthetic material is described in U.S. Pat. No. 4,245,970. The region 
of entry of sewer branch pipes into the main sewer is filled with a filler 
by means of a nozzle passed through an inflatable sealing ring. 
Subsequently, an aperture for passage as far as necessary into the 
interior of the inner pipe is formed by a cutting tool. However, cavities, 
fissures or gaps which may be present at the site of entry often are only 
insufficiently sealed by this technique. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a method of 
producing leak-proof sites of entry into waste water drainage systems. 
Another object of the invention is to provide a method of constructing, 
repairing or modifying waste water drainage systems that avoids the 
monetary costs associated with traditional methods of constructing, 
repairing and modifying a site of entry. 
It is another and more particular object of the invention to provide a 
method suitable both for constructing and renovating sites of entry, and 
for renovating feed pipes with an intact drainage system, and for carrying 
out such work in connection with the renovation of a drainage system by 
the insertion of an inner pipe into the drainage system. 
The invention is a method for producing a leak-proof site of entry into a 
waste water drainage system in a manner that eliminates the need to 
excavate the drainage system and the site of entry. In the method, the 
edge of the site of entry into the drainage system (e.g. a sewer) is 
widened by forming a recess extending along the same edge. The site of 
entry is closed towards the interior of the sewer and from inside the feed 
pipe to form a space encompassing the site of entry. A solidifying, 
sealing mass is then introduced into the space formed at the site of 
entry. After the sealing mass sets, the flow path through the feed pipe 
and into the sewer is cleared of excess sealing mass. Preferably, a cover 
layer of solid or solidifying, insoluble, corrosion-resistant and 
non-ageing material is applied onto the inner face of the site of entry 
which is sealed by the sealing mass. In this manner, a leak-proof and 
strong connection can be made between domestic connection pipes and feed 
pipes entering into a waste water drainage system. Any damaged areas 
present in the region of the site of entry, such as broken out portions of 
pipe, transition gaps and fissures or similar damage, as well as faulty 
areas due to offsets between feed pipes and the entry apertures in the 
sewer wall, can be filled or repaired and replaced by the sealing mass, 
and thus renovated. 
The invention also eliminates some of the problems associated with the 
precision required to renovate sewer connections. For example, a precise 
machining of the entry-side rim of the feed pipe corresponding to the 
curvature of the sewer wall prevailing at the site of entry is no longer 
necessary. Using the invention, it is possible to make this relatively 
complicated spacial intersection form automatically when removing the 
sealing mass, as is typically done in the course of clearing the flow path 
through the feed pipe into the sewer. 
Another embodiment of the method of the invention includes inserting an 
inner pipe into the existing sewer. As an option, filler can be placed in 
the annular space between the inner pipe and the sewer. After placement of 
the inner pipe, and filler if desired, into the sewer, the site of entry 
is widened and sealed as described above. It should be noted that the 
cutting and widening of the site of entry may be effected both from the 
interior of the sewer or main train of pipes as well as from the pipe or 
feed pipe. 
A variant to the last-mentioned embodiment of the invention includes 
introducing an inner pipe into the sewer wherein the diameter of the inner 
pipe is such that the inner pipe also forms a cover at the site of entry 
effectively closing off the interior of the sewer. The sealing mass is 
then introduced at the site of entry as previously described. 
The invention can also be utilized in connecting new feed pipes to existing 
drainage systems. In this embodiment of the method, the feed pipe is 
brought up to the drainage system and a space is maintained between the 
connecting end of the feed pipe and the inner wall of the sewer. This 
space is bridged by introducing the solidifying sealing mass at the site 
of entry and removing the sealing mass present in the flow path of the 
feed pipe. 
The method of the invention is particularly useful if an existing feed pipe 
is to be provided with an inner pipe. In this embodiment, an inner pipe of 
smaller diameter is placed into the existing feed pipe, thereby creating 
an annular space. A sealing mass is then introduced into the area of the 
site of entry. The sealing mass not only seals the site of entry but also 
flows into the annular space defined by the feed pipe and the inner pipe, 
thereby creating a stable and leak-proof connection. 
Another embodiment of the method of the invention that provides improved 
mechanical stability and particularly good anchoring of the sealing mass 
utilizes a double-walled inner pipe wherein the two walls of the inner 
pipe are interconnected by a plurality of radially extending webs. The 
outer wall of the double-walled pipe is provided with apertures in the 
area around the site of entry, or is removed, and preferably is only 
partially removed, so that when the sealing mass is introduced at the site 
of entry, the sealing mass is also guided between the webs and to the 
inner wall of the double-walled pipe.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The invention will now be further explained with reference to examples 
illustrated in the accompanying figures. 
FIGS. 1-5 are longitudinal cross-sections showing various feed pipe 
connections into drainage systems. FIGS. 1a-1c illustrate one embodiment 
of the invention. In FIG. 1a, a sewer 1 extends in the soil 23. A feed 
pipe 6 discharges into the sewer 1 in the region of the site of entry 9. 
As an aid to understanding the usefulness of the invention, the site of 
entry 9 has been drawn to include various types of damage, such as broken 
out portions 13a, transition gaps 13b and fissures 13c. To repair the 
damage present at the site of entry, a sewer inner pipe 3 is introduced 
into the sewer 1, and a feed inner pipe 7 is introduced into the feed pipe 
6. The edge of the site of entry of the pipe 6 is widened by forming a 
recess 15a indicated by the phantom line. By forming the recess, broken 
out portions, gaps and fissures present at the site of entry 9 are largely 
removed. The forming of recess 15a can be accomplished using a milling 
robot or similar cutting device introduced via the feed pipe 6. 
Preferably, the feed inner pipe 7 is not guided all the way to the interior 
of the sewer 1. A space is maintained between the connecting end of the 
pipe 7 and the wall of the sewer inner pipe 3. As shown in FIG. 1b, an 
injection device 16 comprising a feed duct 18 and an injection nozzle 19 
is introduced via the feed inner pipe 7. The inner space of the pipe 7 is 
closed externally of the site of entry 9 by a radially expandable disc 17 
which is in contact with the injection device 16. Sewer inner pipe 3 
present in sewer 1 forms a cover closing the site of entry 9 at the inner 
side of the wall of the sewer 1 creating a space that encompasses the site 
of entry and is defined by the outer wall of sewer inner pipe 3 and the 
disc 17. A pressure-proof, leak-proof connection of feed pipe 6 to sewer 1 
is then created by introducing a sealing mass 12. The sealing mass 12 is 
introduced into the defined space in a sufficient amount and at sufficient 
pressure to fill the entire defined space including the recess 15a and all 
fissures and cracks located therein (e.g. 13a, 13b, 13c). 
As shown in FIG. 1c, after the sealing mass 12 is solidified, a milling 
device 20 or other appropriate milling, drilling or cutting device is used 
to remove sealing mass corresponding to the inner diameter of the pipe 7 
to clear a flow path for the feed pipe 6 into the sewer 1. The milling, 
drilling or cutting device 20 is advanced at the site of entry through the 
feed inner pipe 7 into the interior of the sewer 1, and the solidified 
sealing mass is removed according to the cylinder shape 15 shown in broken 
lines. 
The sewer inner pipe 3, whose wall is still completely closed at the site 
of entry 9 at the time the sealing mass 12 is introduced, is partly 
removed or cut out in registration with the inner space of the feed inner 
pipe 7, together with the sealing mass present in the flow path of the 
pipe 6. Thus, a pressureproof, leak-proof connection 11 is formed which 
consists of the remaining solidified sealing mass 12 and extends from the 
connecting end of the feed inner pipe 7 into the interior of the sewer 1. 
In this manner, an automatic adaptation of the edge shape of the feed duct 
formed with the feed inner pipe 7 to the circumferential shape of the 
sewer 1 is achieved, thus eliminating a complex processing of the 
connecting end of the feed inner pipe 7. 
In the embodiment of the method according to FIGS. 1a-1c, the external 
diameter of the feed inner pipe 7 is only slightly smaller than the 
internal diameter of the feed pipe 6, and the annular gap present between 
these feed pipes 6 and 7 is sealed by the sealing mass 12 entering into 
this annular gap. The sealing mass 12 can also fill gaps present between 
the wall of the sewer 1 and the sewer inner pipe 3 inserted into the sewer 
1. 
The penetration of the sealing mass into the branches of the cavities 
present at the site of entry 9 may be controlled by selection of the 
injection pressure as well as by selection of the composition of the 
sealing mass. Expanding sealing masses are advantageous. A sealing mass in 
the form of a two-component synthetic resin foam that hardens in the 
presence of moisture, that displaces water and that quickly solidifies is 
particularly preferred. A polyurethane foam that swells and thus "crawls" 
is particularly suitable. Such a foam will even enter into gaps of 0.1 mm 
width and harden to a material of considerable static strength. It is 
advantageous to choose a type of foam material which is non-ageing, 
waterproof, and resistant to domestic chemicals as well as to chemical 
aggression by substances present in the soil. A swelling polyurethane foam 
strongly contacts surfaces delimiting the foam body and thus prevents the 
entry of water at the areas of contact while simultaneously providing a 
certain degree of elasticity so that minor movements can be accommodated 
without substantially affecting the leak-proof contact of the foam. Such 
properties can also be attained with other suitable materials. 
The closure of the interior of the feed pipe 6, can be accomplished in 
various ways. An inflatable balloon or a similar closing device can be 
provided on the injection device 16 instead of a radially expandable disc 
17. An inflatable balloon may offer advantages, because it may be guided 
easily through narrow passages. 
FIGS. 2a and 2b illustrate another embodiment of the method. In this 
embodiment, recess 15a is again formed at the site of entry 9. A 
double-walled sewer inner pipe 3a is introduced into the sewer 1 to be 
renovated. The two walls of pipe 3a are interconnected by a plurality of 
radially extending webs so that the wall of this pipe 3a, seen as a whole, 
is formed of a large number of mutually closed compartments. A pipe having 
such a structure has a good mechanical stability with relatively low 
weight and offers increased safety against undesired wall perforations. In 
the region of the site of entry 9, the outer wall of this double-walled 
pipe 3a is provided with apertures 3b or is partly removed. The sealing 
mass introduced in the course of the process into the cavities present at 
the site of entry 9 can enter into the compartments of pipe 3a opened by 
the apertures 3b and thus can anchor itself well in pipe 3a as illustrated 
in FIG. 2b. The slit-shaped apertures 3b may be made before introducing 
the sewer inner pipe 3a into the sewer 1, or they may be made when the 
inner pipe 3a is already in place by means of a correspondingly controlled 
milling robot introduced via the feed pipe 6. The cavities at the site of 
entry 9 are filled as previously described. When the sealing mass has 
solidified, the flow path can be cleared using a milling device or other 
clearing device as previously described. Thus, the leak-proof site of 
entry 10 of the feed pipe 6 into the sewer 1 and its sewer inner pipe 3a 
is formed, as illustrated in FIG. 2b. 
In an alternative embodiment of the method illustrated in FIGS. 2a and 2b, 
a double walled pipe may be used for the feed inner pipe 7. Sealing along 
such a pipe 7 would be in the same manner as that shown for sewer inner 
pipe 3a in FIG. 2b. Such a double-walled design of a feed inner pipe 7 
offers the advantage of a very stable anchoring of the connecting end of 
the feed pipe to the sealing mass. 
FIGS. 3a-3d illustrate yet another embodiment of the method. At the site of 
entry 9, the edge of the entry is provided with a recess 15a (FIG. 3b). 
Again, damaged parts which have an unfavorable shape for the penetration 
of the sealing mass, (e.g. narrow slits and the cavities there behind, or 
lateral offsets 13d of the feed pipe 6) can be removed by this recess. The 
recess 15a is again made by a milling robot introduced via the feed pipe 
6. 
The embodiment illustrated in FIGS. 3a-3d show that even with a sewer inner 
pipe 3 of markedly smaller diameter as compared to the diameter of the 
sewer 1, this inner pipe 3 can form a cover closing the site of entry 9 at 
the inner side of the sewer wall, without requiring filling of the annular 
space 4 there between with a filler. Such an embodiment will be suitable 
if both the sewer 1 and the sewer inner pipe 3 have sufficient static 
stability or strength. When the sealing mass 12 is introduced by means of 
the injection device 16 inserted via the feed pipe 6 (FIG. 3c), the 
cavities located in the region of the site of entry 9, the recess 15a and 
the annular space 4 in the region of the site of entry 9 are filled with 
the sealing mass. The distance passed by the sealing mass 12 into the 
annular space 4 can be adjusted by appropriate adjustment of the flow or 
solidifying parameters of the sealing mass 12 or by adjusting the 
injection pressure. The sealing mass 12 flowing into the annular space 4 
at the site of entry 9 provides a support for the sewer inner pipe 3 in 
the sewer 1. 
Subsequently, as shown in FIG. 3d, the flow path from the feed pipe 6 into 
the sewer 1 and the sewer inner pipe 3, can be cleared by an appropriate 
clearing device 20 forming a cylindrical cut-out 15. Thus, a 
pressure-proof, leak-proof connection of the feed pipe 6 with the sewer 
inner pipe 3 of the sewer 1 is formed, as schematically illustrated in 
FIG. 3d. It should be pointed out that in this finished state, the entry 
aperture formed in the sewer inner pipe 3 registers with the feed pipe 6. 
The originally present lateral offset is eliminated. If desired, a feed 
inner pipe 7 may also be used as shown in FIG. 1a. 
The process may be modified in that the recess 15a can be formed before a 
sewer inner pipe 3 is introduced into sewer 1. Likewise, if desired, the 
annular space 4 between the wall of the sewer 1 and the sewer inner pipe 3 
may be filled with a filler before the sealing mass is introduced into the 
cavities present at the site of entry 9. 
Yet another embodiment of the method is illustrated in FIGS. 4a-4c. These 
figures relate to the renovation of a sewer 1 that has been previously 
renovated by introduction of a sewer inner pipe 3. At the entry aperture 
10 to which the feed pipe 6 is joined, the sewer inner pipe 3 is provided 
with an entry aperture 14 as shown in FIG. 4a. Damaged portions, (broken 
out portions 13a, transition gaps 13b and fissures 13c) may be present in 
the region of the site of entry 9, which require repair. As with the 
previous embodiments, a recess 15a is formed by widening the site of entry 
9. This recess extends to the sewer inner pipe 3. 
Furthermore, in this embodiment the feed pipe 6 is to be renovated by 
insertion of a feed inner pipe 7. The feed inner pipe 7 has a 
substantially smaller diameter than the feed pipe 6 so that there remains 
an annular space 8 between these two pipes. As shown in FIG. 4b, the 
aperture 14 is closed towards the sewer interior by a cover 21. The feed 
inner pipe 7 is closed by a closing device 17 provided on an injection 
device 16 supplied via the feed inner pipe 7. Subsequently, sealing mass 
12 is introduced by the injection device 16 into the cavities located in 
the region of the site of entry 9. As shown in FIG. 4c, when the sealing 
mass has solidified, the cover 21 and the injection device 16 including 
the closing device 17 are removed, and a milling device 20 is introduced 
via the feed inner pipe 7 to clear a path of flow from feed inner pipe 7 
through the solidified mass and into sewer inner pipe 3. This path of flow 
is illustrated by broken lines 15 in FIG. 4c. 
In yet another embodiment of the method, some stages of which are 
illustrated in FIGS. 5a-5d, a defective site of entry of a feed pipe 6 
into a sewer 1 previously renovated by installation of a sewer inner pipe 
3 is repaired so that a leak-proof entry of the feed pipe 6 into sewer 1 
or the sewer inner pipe 3 is formed. The sewer inner pipe 3 provided for 
lining sewer 1 in this instance has a markedly smaller external diameter 
than the diameter of the inner wall of the sewer 1. The annular space 4 
between the outer side of the sewer inner pipe 3 and the inner side of the 
sewer 1 is filled with a filler 5 (i.e. "closed by a dam", as this is 
called in the art). 
In this embodiment, the edge of the entry aperture 10 provided in the sewer 
wall is widened by forming a recess 15a, as shown in FIG. 5b, whereby part 
of the damaged portions, (e.g. broken out portions 13a and fissures 13c) 
are removed. Simultaneously, the aperture 14 in the inner pipe is widened 
and the filler 5 present there is removed. Subsequently, the cavity 
located in the region of the site of entry 9 is covered towards the 
interior of the inner pipe 3 by a covering device 21 (FIG. 5a), and the 
feed pipe 6 is closed towards its feed side by a closing device 17. The 
closed cavity is then filled with a sealing mass 12 by an injection device 
16 comprising a feed duct 18 and an injection nozzle 19. The sealing mass 
12 fills the recess 15a and any damaged portions that might have remained. 
The edge of the filler 5 facing the site of entry and located in the 
annular space 4 between the sewer wall and the sewer inner pipe 3, is 
covered by the sealing mass 12, and thus is protected from a corrosive 
attack by waste water. When the sealing mass 12 has solidified, the cover 
device 21, the injection device 16 and the closing device 17 are removed. 
A cut-out 15 indicated by the broken lines in FIG. 5d is then formed by a 
milling device 20 or other suitable cutting device that removes the 
sealing mass 12 located in the flow path from the feed pipe 6 to the sewer 
inner pipe 3. In this manner a leak-proof entry is created from the feed 
pipe 6 into the sewer inner pipe 3. 
If particularly good corrosion resistance and non-ageing properties are 
desired for the pipe wall surfaces remaining at the site of entry and 
lying in the flow path of the waste water and if an appropriate material 
for the sealing mass cannot be used, (e.g., because the sealing mass has 
to meet other requirements, such as a very good deformability) it is 
possible, as is illustrated in FIG. 5d, to apply a cover layer 22 of solid 
or solidifying, insoluble, corrosion-resistant and non-ageing material to 
the inner face of the entry. This applies equally as well to all of the 
embodiments of the method described herein.