A borehole Casing is installed to prevent the collapse of the walls of the borehole, exclude pollutants from entering the water source at the Borehole, and provide a channel for conveying the water to the surface (or in the reverse direction, for injection).
The borehole Casing also provides housing for the pump mechanism. but not exclusively, PVC) and stainless steel. Unfortunately, the terms "casing" and "pipe" can be confused. There is, however, a distinguishing difference between pipe and casing. Steel "pipe" is manufactured in the cylindrical form at the producing mill, whereas "casing" is made cylindrical by a fabricator from steel sheets or plates.
Such steel casing is fabricated to resist external and vertical forces, rather than the internal burst forces that line pipe is designed to resist. Plastic casing products are extruded, much like seamless steel casing, but like steel casing, engineered (and selected during planning) to resist the pressures exerted by the surrounding materials, forces imposed on it during installation, and corrosion by soil and water environments access to the water source from the surface through unstable formations, and through zones of actual or potential contamination.
Casing should extend above-known levels of flooding, or be positively sealed against flooding flows. For wells screened in sand and gravel, the casing should extend to at least five feet below the lowest estimated pumping level of a well to avoid excessive oxidation, clogging and corrosion at the screen. In consolidated formations, the casing should be sealed securely into firm bedrock.
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| Borehole Casing in Zimbabwe |
An exception may be the case where water immediately on top of the rock is the target. In this case, the well design should be such that the casing is solidly installed and sediment and unsanitary water excluded. forces are known or expected to occur, a self-sealing slip joint may be installed in the casing to allow for vertical movement and prevent collapse. Both carbon alloy steel and plastic well casing are now commonly used successfully around the world.
The plastic casing is increasingly used due to its lightweight, ease of installation, durability, and corrosion resistance. Concrete, fibreglass and asbestos cement casing have also been used with varying degrees of success. Less common metal casing materials such as stainless steel, cupro-nickel alloys, silicon bronze, aluminium, and other nonferrous metals, can be used for casing in special situations where the natural soil and water-quality conditions (primarily severe corrosion potential) dictate their employment, and plastic cannot be used for some reason.
The most common materials for Borehole casing are carbon steel, and plastic (most commonly, Casing must be of the proper length to accomplish its purpose of providing security care must be exercised when placing casing.
AquAmanzi Borehole Drilling Is One Of Zimbabwe’s Leading Borehole Drilling Companies Specialising In Borehole Siting, Borehole Drilling and Borehole Installations.
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Address: 16911 Old SPCA Complex Unit 2,Seke Road, Graniteside.
