Metal working – Method of mechanical manufacture – Repairing
Patent
1991-01-08
1992-04-07
Eley, Timothy V.
Metal working
Method of mechanical manufacture
Repairing
B23P 600
Patent
active
051015455
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of reforming existing gas pipes by repairing the joint portions thereof with a repairing device which is movable inside the pipe under remote control.
BACKGROUND ART
The method of repairing the joint portions of existing gas pipes is already well known which employs a repairing device movable inside the pipe. This method is practiced by moving the repairing device inside the pipe to position the device for the joint portion, and then injecting a liquid epoxy resin agent or like sealing agent into the joint portion as sealed from inside the pipe to seal off a gas leak. The repair work for joint portions of existing gas pipes is performed usually over a length of about 50 m to about 100 m as one span, and the joint portions are arranged usually at a spacing of about 5 m to about 10 m. These joint portions are repaired one after another with the travel of the repairing device inside the pipe regardless of the presence or absence of gas leaks.
In practicing the repairing method, there arises a need to form a work opening in the existing gas pipe to be repaired in order to place the repairing device within the gas pipe and to move the device inside the gas pipe for the repair of the joint portions.
The work opening is conventionally formed by partly cutting away the gas pipe, for example, over a length of about 1 m to about 2 m. A terminal tube for accommodating the repairing device therein is installed in the cutaway portion, as connected to the pipe side to be repaired. The terminal tube is provided with a gate valve at each of its inlet side and outlet side so that the repairing device can be inserted from inside the terminal tube into the pipe having the joint portions to be repaired, with the hazard of gas leakage eliminated by alternately opening and closing the gate valves.
However, the conventional method wherein the work opening is formed by partly cutting away the gas pipe requires the following procedures for forming the work opening and restoring the opening portion to the original state. section of about 50 m to about 100 m as one span, so that an interruption of gas supply over this section will cause inconvenience to many customers who are supplied with the gas from this section. Accordingly, when the gas pipe is to be partly cut away to form the work opening, it becomes necessary to install bypass pipe to ensure the flow of the gas. to shut off the gas by inflating a bag within the gas pipe at each side of the cutaway portion as required for various kinds of gas piping work. cutaway portion of the gas pipe at the pipe side to be repaired, the means for shutting off the gas must be removed from the pipe to be repaired in order to insert the repairing device from inside the terminal tube into the pipe. the repaired pipe must be blocked with the bag again to shut off the gas for the removal of the terminal tube and the gate valves.
As will be apparent from the procedures (i) to (vi), the conventional method requires much labor and time for the formation of the work opening and restoration of the pipe, which result in a longer period and an increased cost for the repair.
DISCLOSURE OF THE INVENTION
The main object of the present invention is to provide a repair method of the type described above in which a work opening can be easily formed and is easily closable for restoration to ensure a shortened work period and a reduced cost.
Other features of the present invention will become apparent from the following description.
The present invention provides a method of repairing the joint portions of an existing gas pipe by a repairing device which is movable inside the pipe under remote control with gas flowing through the pipe, the method being characterized in that the method includes the steps of the gas flowing through the pipe and closing the work opening with a gate valve provided at the work opening externally of the pipe, gate valve for the tube to extend upwardly of the pipe with the gate valve interposed therebetween, through an
REFERENCES:
patent: 4253497 (1981-03-01), Martin
patent: 4492095 (1985-01-01), Brister
patent: 4505295 (1985-03-01), Quin et al.
Fujita Mitsuhide
Miyazaki Yasuo
Mori Yoji
Ohinata Masaaki
Shimazaki Yasuo
Eley Timothy V.
Osaka Bousui Construction Co., Ltd.
Osaka Gas Co. Ltd.
Toho Gas Co. Ltd.
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