1. Field of the Invention
The present invention relates to systems and methods for blocking media flow through a pipe and a system for utilizing the method. Particularly, but not exclusively, embodiments of the invention provide methods and systems for temporarily blocking the bore of a pipe such as, for instance, a gas or water main pipe.
2. Description of the Related Art
Pipelines are used for a variety of purposes, such as, transmitting gas or fluid. In certain instances, it is desirable to interrupt the flow of a gas or fluid, through a given pipeline without shutting down an entire pipeline system; this is commonly referred to as line stopping. For example, it may be desirable to make repairs on a section of the pipeline or replace equipment associated with the pipeline. In these instances, line stopping may be necessary.
A variety of different methods and devices are known for temporarily stopping flow through a pipeline to enable maintenance to be carried out on a particular section of pipe without removing the whole pipe from service. Most of these devices are designed to be inserted through one or more holes drilled in the pipe wall using well known drilling apparatuses designed for operations under pressure. For instance, within the gas industry inflatable stopping bags are widely used. Such bags are designed to be inserted, while in a deflated state, through a hole drilled in the pipe wall and then subsequently inflated to form a sealed blockage in the pipe.
While simple stopping bag devices may be suitable for use in relatively low pressure applications, such as in low pressure gas pipelines, they are less suitable for higher pressure situations. Under these conditions, the bag may tend to be pushed along the length of pipe by the high pressure gas or fluid or to burst. One known technique for addressing this problem is to provide additional mechanical supports for the bag. However, these additional supports require further holes to be drilled into the pipe wall, which can impact the integrity of the pipeline.
Another known technique for stopping the flow of media within a pipeline is by inserting a cylindrical deformable plug through an access hole drilled in the wall of a pipe. After the plug is inserted, it is deformed to prohibit flow of media within the pipe. In these plug designs, the deformable plug includes a mechanical component that engages the opposing pipe wall to compress and deform the plug to seal the pipe. Because the force required to deform the plug can be significant, there is a potential of deforming or cracking the pipe, especially if the pipeline is plastic. In some cases, a separate physical stop is attached to the pipe for the mechanical component to engage instead of the pipe wall. In these cases, however, the physical stop is rigidly attached to the pipe and the engagement of the plug mechanical component can still cause damage to the pipe or separation of this physical stop from the pipe. Yet another method involves the use of a resilient cup-shaped plug with a diameter slightly larger than the inside diameter of the pipe. This plug is delivered inside the pipe and positioned in such a way that its axis coincides with the pipe axis. A problem encountered with these devices is that with increasing pressure within the pipeline, the plug can be difficult to remove from the pipe. Therefore there is a need in the industry for improved line stopping devices and methods.