Title of Invention

A DEVICE FOR DESCALING THE INNER WALL OF A TANK

Abstract

We Claim: 1. A device for descaling the inner wall of a tank comprising a first set of radial arms, the ends of which are in contact with the said inner wall and provided with electromagnets and descaling members for rough descaling opeTations; an axially spaced second set of radial arms, the ends of which are in contact with the said inner wall and also provided with electromagnets and descaling members for fme descaling operations; the said two sets being mounted on a common screw rod, in threaded engagement with the said rod and rotatably driven by a motor, the electromagnets of the second set and the first set being alternately operable to provide a radial force along the arms on the descaling members to grip the inner wall, while the descaling members of the first set and the second set alternately operate to rotate and also move linearly and perform the rough and fme descaling operations, the ends of the second set of arms being operable to grip the said inner wall to hold the device stationary while the first set of arms are rotatablv and linearly driven by the screw rod to enable the rough descaling members to act on the inner wall; and the first set of arms being operable thereafter to grip the said inner wall to hold the device stationary while the second set of arms are rotatably and linearly driven by the screw rod to enable the fine descaling members to act on the said inner wall. 2. A device for descaling the inner wall of a tank substantially as herein described with reference to, and

Full Text

This invention relates to a device for descaling the inner wall of a cylindrical tank, such as, a tank used for carrying chemicals. The word "chemicals' means and includes substances which are either stored in tanks or those which are transported in tanks on vehicles called tankers, including oil and liquids. which react with the inner walls of tanks to form scales. The scales formed are removed from time to time before re-use of the tanks. Such tanks are commonly used in the shipping industry where tankers are employed for transporting chemicals from the harbour to the points of supply. The cylindrical tanks carrying such chemicals are normally of about 20 feet in length and 8 feet in diameter. Conventionally, men are employed to enter the tank (after it is emptied) through a small manhole provided in the wall of the tank. After entry, the men scrape the inner wall of the tank using abrasive materials to descale the wall. Such manual workers are exposed to the following hardships: *The temperatures inside the tanks which are oppressive. *Respiratory problems created by lack of proper ventilation inside the tanks. Musculoskeletal risk factors which are present by reason of awkward postures necessarily adopted by workmen while working inside tanks. Frequent use of vibrating, scraping tools used for descaling causing high level stresses in body joints and the nervous system. The time required to manually descale a tank is about 5 hours to 100 hours. On an average, tank operators require at least 10 cleaned tanks per day to be readied for use and they will have to expend amounts close to 3 lakh rupees per day to carry out the cleaning operations. It is therefore an object of this invention to propose a device as aforesaid to eliminate, or at least greatly minimise, the drawbacks stated above. The device for descaling the inner wall of a tank, according to this invention, comprises a first set of radial arms, the ends of which are in contact with the said inner wall and provided with electromagnets and descaling members for rough descaling operations; an axially spaced second set of radial arms, the ends of which are in contact with the said inner wall and also provided with electromagnets and descaling members for fine descaling operations; the said two sets being mounted on a common screw rod, in threaded engagement with the said rod and rotatably driven by a motor, the electromagnets of the second set and the first set being alternately operable to provide a radial force along the arms on the descaling members to grip the inner wall, while the descaling members of the first set and the second set alternately operate to rotate and also move linearly and perform the rough and fine descaling operations by the rotating arms, the ends of the second set of arms being operable to grip the said inner wall to hold the device stationary while the first set of anns are rotatably and linearly driven by the screw rod to enable the rough descaling members to act on the inner wall and the first set of arms being operable thereafter to grip the said inner wall to hold the device stationary while the second set of arms are rotatably and linearly driven by the screw rod to enable the fine descaling members to act on the inner wall. This invention will now be described in further detail by reference to the accompanying drawings which illustrate by way of ex ample, and not by way of limitation, one of various possible embodiments of this invention Fig. 1 illustrating the end view of the first and second set of radial arms of the embodiment installed within a tank-Fig. 2 illustrating the side view of the assembly of the embodiment within the tank Fig. 3 illustrating the perspective view of the assembly of the embodiment within the tank The inner wall of the cylindrical tank T, usually made of steel which is used for storing chemicals or for transporting them is to be descaled after use. The device proposed herein is limited to the task of descaling the inner wall W only; not the two end walls of the tank. Descaling the end walls will have to be carried out in the know way, manually. The device is lowered into the tank through a man hole provided therein, hiside the tank, the device is assembled. A first set of radial arms Al, have their ends in contact with the inner wall W of the tank and provided with electromagnets El and descaling (rough abrading) members Dl for rough descaling operations. A spaced second set of radial arms A2 have their ends in contact with the inner wall W of the tank and also provided with electromagnets E2 and descaling (fine abrading) members D2 for fine descaling operations. The said two sets are mounted in threaded engagement on a common screw rod R and their arms rotatably driven by a motor M. Thus, when the motor drives the arms, the respective sets are simultaneously moved hnearly along the screw rod. The arms are spring loaded so that their ends are firmly in contact with the inner wall W. Now, when tJie rough descaling operation is to be taken up, the electromagnets E1 are energised. This causes the arms A1 to firmly grip the inner wall W under the radial force exerted by the electromagnets. In this condition, the electromagnets El are not energised. On the other hand the motor M is activated to rotatably drive the arms Al, causing the abrasive members at their ends to scrape the inner wall and thus rough-descale it. Simultaneously, the arms move linearly on the screw rod R for a predetermined distance to perform the rough-descaling operation. The pitch of the screw is selected to ensure complete coverage of the circular surface Next, the movements of the arms Al is halted and the electromagnets E2, energised. This causes the arms A2 to firmly grip the inner wall W under the radial force exerted by the electromagnets. In this condition, the electromagnets E1 are de-energised. The motor M is now activated to rotatably drive the anus A2, causing the abrasive members at their ends to scrape the inner wall and thus fine-descale it. Simultaneously, the amis A2 move linearly on the screw rod R for a predetermined distance to perform the fme-descaling operation. The procedure repeats, altemately activating the two sets to complete the descaling operation. The terms and expressions herein are of description and not of limitation having regard to the scope and ambit of this invention. We Claim: 1. A device for descaling the inner wall of a tank comprising a first set of radial arms, the ends of which are in contact with the said inner wall and provided with electromagnets and descaling members for rough descaling opeTations; an axially spaced second set of radial arms, the ends of which are in contact with the said inner wall and also provided with electromagnets and descaling members for fme descaling operations; the said two sets being mounted on a common screw rod, in threaded engagement with the said rod and rotatably driven by a motor, the electromagnets of the second set and the first set being alternately operable to provide a radial force along the arms on the descaling members to grip the inner wall, while the descaling members of the first set and the second set alternately operate to rotate and also move linearly and perform the rough and fme descaling operations, the ends of the second set of arms being operable to grip the said inner wall to hold the device stationary while the first set of arms are rotatablv and linearly driven by the screw rod to enable the rough descaling members to act on the inner wall; and the first set of arms being operable thereafter to grip the said inner wall to hold the device stationary while the second set of arms are rotatably and linearly driven by the screw rod to enable the fine descaling members to act on the said inner wall. 2. A device for descaling the inner wall of a tank substantially as herein described with reference to, and

Documents:

1682-CHE-2008 AMENDED CLAIMS 25-02-2014.pdf

1682-CHE-2008 POWER OF ATTORNEY 25-02-2014.pdf

1682-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 25-02-2014.pdf

1682-che-2008 claims.pdf

1682-che-2008 correspondence-others.pdf

1682-che-2008 description(complete).pdf

1682-che-2008 drawings.pdf

1682-che-2008 form-1.pdf

1682-che-2008 form-26.pdf