Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,... – Advancing subterranean length of pipe or cable
Reexamination Certificate
1999-05-14
2001-08-14
Will, Thomas B. (Department: 3673)
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
Advancing subterranean length of pipe or cable
C138S097000, C138S098000, C264S269000, C277S314000, C277S602000, C277S904000
Reexamination Certificate
active
06273644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the repair of high pressure gas or water service pipes which contain a section(s) of leaking or deteriorated pipeline. More particularly, the present invention concerns the insertion of a unique stopper assembly for discontinuing or sealing the flow of the high pressure service into the old section of the high pressure service pipe to be repaired. The stopper assembly further facilitates the insertion of a new, or replacement service pipe within the leaking or deteriorated section, and the pumping of a sealant between the old pipeline and the newly-inserted pipeline. The sealing aspect of the stopper assembly is operated or controlled by a tool means also inserted through the high pressure service pipe, and internally of the stopper assembly. The invention also facilitates pressure testing of the sealed pipeline section prior to returning the high pressure service.
2. Discussion of the Prior Art
Previous servicing and/or replacement of underground high pressure service pipes typically involved excavation of areas adjacent the affected pipe and temporary termination of the flow of gas, either at the point of leakage or at a valve location upstream of the leakage, usually at the connection with the main. Past methods proved to be time consuming and costly, thus it could be appreciated that an alternative method was sought where the replacement of the leaking or deteriorated section could be performed without the need for excavation.
Early improvements involved the insertion of a new pipe section into the old pipe section without the need for excavating, but those early attempts failed to solve higher pressure system sealing. Very early methods involved pumping sealant in between the pipes without the ability to visually confirm a complete filling of the void between the old and new pipes.
Furthermore, prior systems failed to provide a method for pressure testing the repaired section at the seal point before returning the section to service. As these systems typically required the use of a temporary plug in the sealing process wherein the plug was merely removed after sealing stage was completed.
A much more sophisticated service pipe insertion apparatus and method is described in pending U.S. application Ser. No. 08/811,521, to the present inventor. That device solves some of the problems described immediately above, but is limited to use in very low pressure gas systems which are typically held at about six inches of water column pressure. That device provided a hollow nosecone assembly for receiving on one end thereof, the new pipe to be inserted within the deteriorated or leaking old pipe. The nosecone assembly and the new piping was typically fed from the gas meter end, upstream towards the gas main, with the nosecone proper being disposed between the main and the leak. The nosecone assembly included a removable plug that interconnected with the nosecone proper on one end thereof and which received a sealant supply tube on the other end thereof. The sealant supply tube was concentrically received within the newly provided service piping, and thus extended co-extensively to the same location where the new service pipe was inserted (gas meter). At the meter location, a sealant is initially pumped through the sealant tubing, eventually exiting at the end of the plug which was inserted into the nosecone proper. Sealant exit points on the nosecone proper communicate the sealant from the removable plug to the volume of area existing between the old piping and the newly inserted piping. The sealant then reverses its flow direction so that all entrapped air is purged from the volume between pipes, until the sealant again returns to the inlet pumping location. In this way, the entire section of piping from the meter to the nosecone assembly is purged of air and completely sealed. The procedure required a lengthy sealant cure time to pass before continuing, a cured-in-place seal being effected within the nosecone. The removable plug and sealant tubing, being concentrically inserted within the new service piping, is then removed thus re-establishing gas flow from the live side of the assembly into the newly inserted service piping.
The apparatus and method of the present invention on the other hand comprises a modification of the device and method described in U.S. Ser. No. 08/811,521 by providing novel stopping or sealing means for terminating the flow of a higher pressure gas service. Unlike the earlier device which used fins with sealant backing to seal the gas, the device of the present invention utilizes a stopper assembly for creating a two-point sealing of the service line. The apparatus of the present invention also introduces a unique sealant introduction means and methodology for feeding the sealant in between the gap which exists between the old and the new pipes. The present apparatus also provides for pressure testing the system at the seal point, purging air from the system. The present invention does not have a cure time waiting period once the trap door is closed.
SUMMARY OF THE INVENTION
The present invention involves a service line pipe repair assembly for use in a high pressure piping system whereby a new pipeline is inserted into an old pipeline from a gas receiving-destination point, such as the area of a gas meter, without the need to excavate. The apparatus is inserted through the old pipe to a point known to be upstream of the leaking or deteriorated area, and in extreme cases, the insertion may extend the entire length of the old gas service pipe, namely from the meter to the gas supply main. Contiguous with the new pipe is a stopper assembly which forms a seal between the old and the new pipe, thereby terminating live gas service.
The unique stopper assembly effects a seal through internal manipulation of a section thereof, which causes a compression sleeve and nut to compress a pair of spaced elastomeric sleeves. The compression of the sleeves creates a ballooning effect on each sleeve, which in turn seals the area between the apparatus and the old pipe, thereby stopping gas flow. The expanded sleeves undergo a pressure test by means of introducing nitrogen through a weep hole located at the point of seal. Then, a removable plug and sealant tubing, which also forms part of the apparatus, is then inserted into the new service piping, whereby a sealant is introduced into the sealant tubing, to the point where a secondary seal is established. A sealant introduction means allows the sealant to be discharged from the sealant tubing through a series of exit points in the introduction means. Since the stopper assembly is sealing the line service pipe immediately ahead or upstream of the apparatus, the sealant is forced to change direction and travel backwards, but only through the annular space existing between the old pipe and the new pipe. The sealant then discharges near the sealant's point of entry, thereby allowing visual observation and confirmation that the annular space is completely sealed and that all air is purged out of the air space volume existing between the old and new pipes. Thereafter, the sealant tubing and the plug are withdrawn from within the new piping. Pressure testing ensures that the pipe replacement procedure has been successfully performed. A drilling tool is then inserted through the new piping until the drilling tool encounters a pressure disk/stop flange, which is incorporated into the distal end of the stopper assembly. The destructive drilling of the disk/plug opens the flow of high pressure gas to an internal passageway, common within the entire stopper assembly, and since that same passageway is in fluid communication with a coextensive internal passageway of the new piping, high pressure flow is reestablished. The drilling tool is then removed from the new piping and the new piping is then reconnected to the gas meter.
REFERENCES:
patent: 1471184 (1923-10-01), Miles
patent: 2377615 (1945-06-01), Crane
patent: 2522171 (1950-09-01), Furman
Barrett Robert E
Gobin Thomas V.
Konwinski Gregory M.
Price Dennis D.
Orum & Roth
Pechhold Alexandra K.
Will Thomas B.
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