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(11) Patent Number: KE 45
(45) Date of grant: 22/04/1995
(12) PATENT
(51)1PC (7): E03B3/06; E03F5/02; F16L9/22

(21) Application Number: KE/P/1996/0191
(22) Filing Date: 21/11/1996
(31) Priority Number:
(32) Priority Date:
(33) Priority Country:
(73) Proprietor(s): KENTAINERS LTD P.OBOX 42126 Nairobi
(72) Inventor(s): Nikhil Shah
(74) Agent:
 (54) Title: A wall casing device for stabilizing and reinforcing walls of wells and the method of manufacture of such device or sections thereof.
(57) Abstract
A tubular open-ended well casing device made by rotational moulding process or any other plastic process using polyethylene or any other suitable polymer as raw material fastened together with another such casing and so on to form a cylindrical tube of required length to line the walls of wells and stabilise and reinforce such walls. Alternatively, such cylindrical casing is cut into required number of curved sections that are then fastened together to form a cylindrical casing. Further alternatively, a plurality of sections are manufactured by rotational moulding process or any other plastic process using polyethylene or any other suitable polymer now materials as aforesaid. The sections so cut or manufactured as sections are then fastened together to form a cylindrical well casing device and one complete well casing device is then fastened together to the next well casing device to form an open-ended cylindrical tube of required length to line the walls of wells and stabilise and reinforce such walls.
Cited Documents
US 2568113,DE 1559176
 
A WELL CASING DEVICE FOR ST ABILISING AND REINFORCING WALLS OF WELLS AND THE METHOD OF MANUFACTURE OF SUCH DEVICE OR SECTIONS THEREOF This invention relates to a cylindrical device for stabilising and reinforcing walls of wells and the method of manufacturing of such device or sections of such device.
This invention has particular, but not exclusive, application for stabilising and reinforcing walls of wells and it is to be understood that it could be used in other applications such as a mould form to hold up for example soil when building culverts or to hold a mass of concrete mixture to make a column.
In several locations in Africa and other parts of the world, communities get their water supplies from wells, which are dug out by hand using only the simplest tools. Wells have varying diameters depending on soil type and depth, although they are always wide enough to accommodate a man. These wells are often constructed in unstable soils and the walls are susceptible to collapse unless they are reinforced. A well casing is an open-ended cylinder of
any material to line the walls of wells to stabilise and reinforce such walls and to prevent them from caving in. It is normally about one meter in height but varies in width according to the diameter of the well.
Currently, cylindrical concrete sections and cylindrical corrugated sheet metal sections are used to alleviate this problem. Concrete cylindrical sections are normally cast in metal moulds at the site of the well from sand, cement, water and ballast. There are, however, several drawbacks with this method. Firstly, if the area is remote, the cost of transport of these heavy items is very high. Secondly, it takes up to a week for one cylindrical section to cure properly in the mould and, therefore, it takes up several weeks to complete one well. Thirdly, as in any concrete product, a skilled artisan must be hired for the job. Fourthly, casting and curing requires water and in semi-arid and arid areas where these wells are normally located, water is a precious commodity and difficult to obtain. Cylindrical Corrugated Sheet Metal Sections are much faster to assemble and are light to transport. However, because they are made of metal, they rust quickly in a wet environment.
The present invention relates to a new moulded cylindrical well casing, which is comparatively thin, light in weight and yet substantially rigid, made by rotational moulding process. This is a very versatile process and it allows the use of several different kinds of polymer raw materials including polyethylene, nylon and polycarbonate to make well casings. In rotational moulding, a metal mould containing a polymer raw material is rotated on one or more axes in a heated environment. The raw material adheres to the inner surface of the mould forming its shape through heating and subsequent cooling. However, this well casing device can also be made by alternative plastic processes such as injection or blow moulding process or thermoforming process.
The object of the present invention is to present a solution which, under the circumstances, constitutes an improvement for use in places and situations where it is not possible or practicable to make or use or erect concrete well casings or corrugated sheet metal well casings.
A number of embodiments of the well casing device according to the Invention are its characteristics namely, that it is thin, light in weight and yet substantially rigid for stabilising 50 and reinforcing soils in suitable locations and in addition, that its sections (whether cut from the whole cylinder or manufactured as sections) are capable of being nested and stacked on top of each other for ease of transportation and to save transportation costs, that they are capable of being delivered with limited transport capacity or even by aeroplane to the most primitive and remote locations with minimal or no infrastructure, that they are capable of being assembled with speed by unskilled workers and that if the well dries up the well casings lining its wall are capable of being dismantled and carried away and re-assembled at another location with ease and minimal transportation costs.
In the present invention, the cylindrical well casing device shown in Figure A indicated as (1) is made from polyethylene but it can also be made from a number of other polymers. This is a totally new concept. It is made in two layers: an outer layer and an inner layer. The entire outer layer is shown in Figure B-1 indicated as (2) and it is made of normal polyethylene and the second inner layer also shown in Figure B-2 indicated as (3) is made of foamed polyethylene. Foamed polyethylene incorporates an active agent that, once all the polyethylene has melted, decomposes and releases inert gases. These gases create small bubbles in the polyethylene layer, increasing its thickness. This is the foaming process. This second foamed layer 5 provides the necessary strength and rigidity to this casing to stabilise and reinforce the walls of the wells.
 Although in the present invention, the well casing device is made of two layers as stated
above, it can also be made of one single layer of Foamed Polyethylene or other suitable foamed polymer as described above and in that case there will be only one layer of Foamed Polyethylene or other suitable polymer in place of the two layers viz, the inner layer shown in Figure B-2 indicated as (3) and the outer layer shown in Figure B-I indicated as (2).

The well casing is manufactured as one complete cylinder and then slit into the required number of sections. Alternatively, a desired number of curved sections of a cylinder shown fastened together in Figure D and indicated as (5) can be manufactured as separate units. The cylindrical well casing is manufactured and can be supplied as one complete (uncut) cylinder or it can be cut into a number of required sections to allow for nesting and stacking of these sections during transportation and they can then be fastened together at or near the wells to form a complete cylindrical casing. For the purpose of illustration, Figure D attached hereto shows how a plurality of sections (three sections in this illustration but it could be of any plurality of sections) are fastened together and assembled. A section shown in Figures and 3-2 is fastened to another similar section as shown in Figure C indicated as (4) and a similar third section is fastened together 5 to these two sections to form the cylinder as shown in Figure D indicated as (5). It is also designed so that one completed cylinder can be fastened to the next complete cylinder or to a section or sections of an uncompleted cylinder as shown in Figure E indicated as (6), so that a whole tube made up of a plurality of such cylinders can be assembled to form the lining of wells of varying length. To fasten I these sections together, nickel plated inserts shown in Figure A and indicated as (7) and galvanized bolts shown in Figure C and indicated as (8) and also shown in Figure F-2 and indicated as (8) with galvanized washers shown in Figure F-2 and indicated as (9) are used. These inserts, bolts and washers are rustproof.

The nickel-plated inserts (7) are moulded into the plastic well casings at a number of pre determined locations two of which are, for purpose of illustration, shown in Figure A and indicated as (7) and the casings (or sections thereof) are drilled, after their manufacture, again at a number of pre-determined locations two of which are, for purpose of illustration, shown in Figure A and indicated as (10) so that these casings can be easily assembled by an unskilled worker. Since the well casing devices are made from polyethylene (or any other suitable polymer) and use fittings protected by nickel or zinc, the products are long lasting in wet environment.
The rotational moulding process is a low pressure process that imparts high impact strength and low stress properties to its products and thus the casing devices (or the sections of casing devices so manufactured retain a high degree of flexibility and shock resistance and are suitable for long distance transportation with minimal or no damage. The sections of the device are nestable and stackable on top of each other and, therefore, easy and inexpensive to transport even to remote areas. The polyethylene or any other suitable polymer used to manufacture these casings (or sections) is stabilized against ultra violet rays of the sun. This makes these well casing devices ideal for outdoor use in any environment. These well casing devices are also suitable for use in extreme conditions and in temperatures ranging from -40 to +60 degrees Celsius. These well casings are rustproof and, therefore, durable.

In the event of the well drying up, the casing devices lining its walls can be dismantled and re-assembled in another location using unskilled workers and with minimal costs.
 
CLAIMS:
We claim: -
I. A well casing device for stabilising and reinforcing the walls of wells, comprising:
a. a plurality of curved sections (either cut after manufacture of the whole casing as a unit or alternatively manufactured as such curved sections) of substantially rectangular shape to be assembled for forming one open-ended cylinder of any diameter, each section comprising two end portions extending in the longitudinal axis of the cylinder to be formed, one of which is slightly bent outwardly and the other slightly bent inwardly, thereby forming mounts suitable for an engagement with the corresponding mounts of a further section so that a predetermined number of sections can be assembled for forming the said cylinder;
b. a plurality of inserts, bolts and washers respectively arranged on the edges of each section to allow a detachable fastening of the sections to each other in circumferential direction to form the cylinder, and
c. a plurality of recessed portions provided on one of the circumferential edges of each section protruding inwardly in radial direction of the cylinder, and a plurality of concave portions protruding outwardly from the sections in radial direction of the cylinder provided in the other of the circumferential edges of the sections, so that each cylinder consisting of the said plurality of sections can be detachably mounted on a further cylinder also consisting of the said plurality of sections;
Wherein each section is formed of two layers of differently treated polymer material for increasing rigidity of the said sections, or alternatively wherein each section is formed of only a single layer of treated polymer material for increasing rigidity of the sections.

2. A well casing device in accordance with Claims 1 wherein polyethylene is used in the manufacture of such device or in the manufacture of sections of such device.
3. A well casing device in accordance with Claims 1 and/or 2 wherein treated polyethylene is used in the manufacture of such device or in the manufacture of sections of such device.
4. A well casing device in accordance with to Claims 1, 2, and 3 where any other polymer material is used to manufacture the well casing device or sections thereof by rotational moulding process or any other plastic process.
5. A well casing device in accordance to Claims 1, 2, 3, and 4 where a plurality of sections of a well casing device are fastened together to form one cylindrical casing
6. A well casing device in accordance with to Claim I, 2, 3, 4, and 5 where moulded-in inserts are incorporated as an integral part of the well casing device during its manufacture or of the sections of such device during their manufacture.
7. A method of manufacturing the well casing device of claim l of any diameter and height using the rotational moulding process or any other suitable plastic process either as one complete whole casing to be first cut and then assembled to again form a complete casing or as a plurality of curved sections thereof to be assembled to form a complete casing, in both cases for stabilising and reinforcing walls of wells.
8. A method of forming a casing device for stabilising and reinforcing soils by using the casing device in accordance with Claims 1, 2, 3, 4, 5, 6 and/or7.
9. A design in accordance with each of the Claims 1 to 8 above as shown in each of the Figures A, B, C, D and E and any design or designs derived there from to allow for a complete well casing device of any dimensions and/or for any plurality of sections of the well casing device of any dimensions.
 

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