Brushing – scrubbing – and general cleaning – Implements – Pipe – tube – or conduit cleaner
Reexamination Certificate
1999-11-23
2001-08-14
Till, Terrence R. (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Pipe, tube, or conduit cleaner
Reexamination Certificate
active
06272713
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the cleaning of piping systems both above and below grade, and in particular where system configuration or operator preference requires the use of a cleaning device of spherical shape to travel through piping. Devices for cleaning pipe are commonly referred to as “pigs” and the procedure as “pigging”.
BACKGROUND OF THE INVENTION
Devices called pigs are used to clean piping systems for removal of materials that affect flow efficiency or removal of materials that can be corrosive to the system. Pigs use an oversize fit to create a seal so that it can be pushed through the system by gas or liquid (i.e. fluid) pressure. In most cases the product in the system is used to propel the pig. The oversize interference fit provides a cleaning action.
In contemporary piping systems there has been a trend to use high yield strength thin wall pipe for buried pipe, as is allowed by piping codes, because it is less expensive to build a system with this pipe than lower yield strength heavy wall pipe. Where the system comes above grade at the inlet and outlet end, heavier wall pipe is used according to accepted design codes and corrosion allowance. Heavier wall pipe is often used when a buried system crosses beneath roads, rivers, streams and lakes.
The result of this mix of pipe is a change in internal diameter. Pipe outside diameter of any nominal size remains the same as is standard in the pipe industry. The internal diameter reduces with an increase in wall thickness. Conventional pigs utilizing cups, discs, scrapers and brushes with a central post or mandrel can be designed to flex or move to accommodate internal diameter changes where piping system design allows for their long length.
Spheres or balls are used for pigging piping systems where the shape of fittings only allow a spherical pig to pass through. For example, systems that have many branch lines often are collected into a header system that uses tee connections between the branch line and the header. The only shape that can change direction laterally in a round pipe is a sphere. In addition, some pig launching and receiving devices are designed to accept spherical pigs only.
Sphere pigs are presently manufactured as solid elastomer, foam core with an elastomer skin or wall, and hollow and inflatable elastomer. All have disadvantages.
Solid spheres do not reduce diameter easily when required, and the smooth surface does not have any scraping ability. Because solid elastomer sphere pigs do not compress easily when there are internal diameter changes, they must be sized for piping at the launch and receive end of a piping system for the ability to manually insert the pig into the heavier wall pipe and for the ability to move through the system with reasonable pressure. This then makes the sphere too small to seal or clean in typical thin wall pipe sections where the internal diameter increases. Further, a smooth or relatively smooth spherical shape has no scraping edges to allow effective cleaning.
The elastomer skin of foam core sphere pigs easily cuts and tears which reduces usable life. The foam core which is open cell can absorb product from the system which can be toxic and/or volatile, making them dangerous to handle or transport. Inflatable sphere pigs are filled with liquid (usually a water and glycol mix) to inflate them to the required diameter. Once the sphere is inflated it is not flexible for change in internal diameter.
Inflatable spheres are complicated and expensive to manufacture, requiring inflation valves to be manufactured into the sphere and special, expensive equipment is required to inflate them. If the elastomer shell or wall should be cut or tear, the sphere will deflate and lose the seal required for travel through the pipe.
None of these spherical designs have deep scraping edges perpendicular to the pipe wall to make them effective scrapers. Some spheres have wire brush strips bonded to the outside surface for scraping but they lose the pressure seal through the bristles which can cause them to slow or stop. The bristle strips also add structure so the sphere it is even more firm and will not reduce for pipeline diameter changes.
There is therefore a need for an effective sealing and scraping spherical pig for use in piping systems designed to only allow for spheres, or because of operator preference. The pig should be generally spherical to fit or travel through pipe anomalies (e.g. elbows, tees, etc.), it should transition through internal diameter changes while still maintaining a pressure seal and yet should provide aggressive scraping action.
SUMMARY OF THE PRESENT INVENTION
The device of the present invention is intended for cleaning and displacing materials in gas and liquid piping system, where often there is a mix of larger and smaller internal diameters due to changes in wall thickness, and short radius bends or side branch turns, while being propelled by the gas or liquid. The design allows the device to flex through varying internal diameters of pipe and fittings. The shape of the three dimensional geometric pattern radiating from the device's inner core and perpendicular to pipe wall surface provides a pressure seal and scraping action not provided by a relatively smooth spherical shape.
In one aspect, therefore, the invention provides a cleaning device for the interior of a pipeline comprising:
a body having a core portion and a generally spherical outer portion about said core portion, said outer portion having a plurality of spaced cells defining a plurality of interconnected elongate wall members of resilient material extending radially from said core portion to define an outer edge portion for engaging said interior of said pipeline to form a pressure tight seal therewith to scrape and clear said interior of unwanted substances as said body travels through said pipeline.
In another aspect the invention provides a device for cleaning the interior of a pipe comprising:
a body having an inner core and a generally spherical outer shell of resilient material enveloping said inner core, said outer shell being formed by an interconnecting pattern of elongate wall members extending circumferentially along said inner core and extending radially from said inner core to define a plurality of outer edges, said outer edges engaging said interior of said pipe to form an interference fit therewith for allowing said body to be propelled through said pipe by a pressurized fluid, wherein said outer edges form scraping means to scrape said interior and displace any foreign substances as said body is propelled therethrough.
In yet another aspect, the invention provides a device for cleaning inside a pipeline carrying a fluid under pressure comprising:
a core of resilient material;
a generally spherical shell of resilient material surrounding said core;
said shell having a plurality of spaced cavities defining a geometric pattern of elongate wall members extending radially from said core to define outer edges;
said core and wall members being sized so that said outer edges form an interference fit inside said pipeline; and,
said wall members being arranged so that said shell forms an adequate seal inside said pipeline to allow said device to be propelled through said pipeline by said fluid to dislodge and clear said pipeline of foreign substances.
REFERENCES:
patent: 2258174 (1941-10-01), Chawner
patent: 2539354 (1951-01-01), Minyard
patent: 4336074 (1982-06-01), Dinkelacker
patent: 4406030 (1983-09-01), Platts
patent: 4550466 (1985-11-01), Schmitz
patent: 5105498 (1992-04-01), Dinkelacker
patent: 1214853 (1960-04-01), None
patent: 603441 (1978-04-01), None
Malyszko Thomas E.
Till Terrence R.
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