FIELD OF THE INVENTION
The present system, in general relates to a method for manufacturing of a refrigerant refillable gas cylinder, and in particular relates to a method for manufacturing and testing of a 13.6 Litre or any other size or thickness refrigerant refillable gas cylinder.
BACKGROUND OF THE INVENTION
Various international standards exist for high strength LPG cylinders. These standards specify requirements for hot rolled steel sheets/strips/coils of high tensile strength grades as raw material, intended for manufacturing welded gas cylinders. Steel weldments are normalized to refine the structure within weld- affected area and modification of residual stresses. These grades are produced in India and supplied to customers for export quality cylinders. In India, LPG grade 15 (YS: 240 MPa minimum) is being produced as per IS 6240 : 2008 ‘Hot rolled steel plate (up to 6 mm) sheet and strip for the manufacture of low pressure liquefiable gas cylinder and liquefied petroleum gas (LPG) containers for automotive use (fourth revision)’.
There is a need to include high strength grades or to formulate a separate specification for this. 20 Keeping this in view, to formulate a separate specification in line with ISO 4978 : 1983, ‘Flat rolled steel products for welded gas cylinders’. This will facilitate production of thinner gauge gas cylinder, which in turn reduce the weight of domestic/auto and industrial cylinder. Benefit of these light weight cylinders includes more number of cylinders per tonne of steel and ease of handling and transportation. For all the tests specified in this standard (chemical/physical/others), 25
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the method as specified in relevant ISO Standard may also be followed as an alternate method. In the formulation of this standard, assistance has been derived from ISO 4978: 1983 ‘Flat rolled steel products for welded gas cylinders’.
OBJECTIVE OF THE INVENTION 5
The prime objective of the present invention is to provide a method to manufacture a 13.6 litre or any other size or thickness refrigerant refillable gas cylinder which is light in weight as compared to existing cylinders providing easy handling and transportation in turns of more number of cylinders per tonne.
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BRIEF DESCRIPTION OF THE DRAWINGS
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Figure 1 is depicting the preferred embodiment of the present invention disclosing the process 15 flow diagram of the proposed manufacturing method of a refrigerant refillable gas cylinder.
Figure 2 illustrates the Sectional elevation of a cylinder produced by an embodiment of the present invention.
Figure 3 illustrates the details of the Shroud and marking produced by an embodiment of the present invention. 20
Figure 4 illustrates the details of Bung produced by an embodiment of the present invention.
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Figure 5 illustrates a circumferential weld by joggling method.
DETAILED DESCRIPTION OF THE INVENTION
The following is a detailed description of exemplary embodiments to illustrate the principles of the invention. The embodiments are provided to illustrate aspects of the invention, but the 5 invention is not limited to any embodiment. The scope of the invention encompasses numerous alternatives, modifications and equivalent; it is limited only by the claims.
Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. However, the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical 10 material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.
The preferred embodiment of the present invention is a manufacturing method of a refrigerant refillable gas cylinder comprising the following steps with reference of figure 1.
- receipt of a raw material; 15
- circle cutting of the raw material;
- half draw at deep draw press;
- trim the drawn halves to the required size of half;
- (a) bung hole piercing on upper halves followed by dimensional checking of bung hole that is diameter and eccentricity of bung hole then bung welding to get bung 20 welded halves and then after joggling and buffing on upper half ;
(b) edge grinding of halves followed by foot ring welding;
- assembly of halves;
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- buffing of the assembled halves;
- circumferential welding;
- tack welding on shroud with cylinder;
- dimensional and welding inspection of the cylinder followed by putting a serial number to the cylinder and batch number punching; 5
- normalizing temperature at 9000 ± 200 C;
- applying hydrostatic test at specified 6.57MPa test pressure;
- checking for no leakage in the cylinder body followed by shot blasting;
- zinc metalizing of the cylinders with required thickness;
- rolling of the cylinder on a rolling machine using steel balls to clean inside the 10 cylinder;
- single coating of epoxy prime on the cylinder;
- single coating of PU (Polyurethane) paint on the cylinder;
- taping of the bung followed by valve fitting; and
- air filling to the specified air pressure. 15
Another embodiment of the present invention is the manufacturing method of the refrigerant refillable gas cylinder comprising the aforesaid steps including inspection of the received raw materials followed by various testings on the cylinder, wherein inward quality of received raw materials (HR coil for shell/body bung, MIG wire, Ar+ CO2 Zinc wire, HR coil for foot 20 ring/shroud)are inspected as per requirement; before circle cutting the HR coil confirm to IS 15914, HS 345 checking for width and thickness to meet the requirement as specified; post zinc metallization, all the cylinders are to be rolled on rolling machine using steel balls/TCE to clean inside the cylinder followed by checking the internal cleaning using 6 watt bulb for any rust or
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any other foreign particles inside the cylinder; one coat of epoxy primer passing through baking oven at temperature 90±100 C for 25 to 30 minutes and flash off time 20 to 25 minutes followed by one coat of PU paint passing through baking oven at temperature 90±100 C for 25 to 30 minutes and flash off time 20 to 25 minutes then checking paint test adhesion test approx. 500PSI using alcometer, gloss at 200 and 600, nail hardness test, pencil hardness test, salt spray 5 test and humidity test, thickness using coatmeter, all as per requirements; after air filling and pneumatic, the cylinder body is offered to BIS or any third party for inspection and releasing the cylinders from which one cylinder from first 202 cylinders is chosen for mechanical testing and one cylinder is chosen for Bust test as per IS 3196-II and III; if the testing of the sample cylinder taken for mechanical and burst test is cleared then make the certificate and released the cylinder 10 for dispatch.
Furthermore, the method disclosed in the present invention is applicable for manufacturing of 13.6 litre or any other size or thickness refrigerant refillable gas cylinder wherein the diameter of the circle cutting is 460 mm and the thickness of the circle cutting is 3.7 mm, internal diameter 15 and height of the halves are 226 mm and 198±2 mm respectively, diameter and eccentricity of the bung hole are 52 mm and 2 mm respectively and total height of the cylinder is 506±10 mm.
Although preferred embodiments of the invention has been illustrated and described, it will at once be apparent to those skilled in the art that the invention includes advantages and features 20 over and beyond the specific illustrated construction. Accordingly it is intended that the scope of the invention be limited solely by the scope of the hereinafter appended claims, and not by the foregoing specification, when interpreted in light of the relevant prior art.

CLAIMS
We claim:
1. A manufacturing method of a refrigerant refillable gas cylinder comprising the steps of:
- receipt of a raw material;
- circle cutting of the raw material; 5
- half draw at deep draw press;
- trim the drawn halves to the required size of half;
- (a) bung hole piercing on upper halves followed by dimensional checking of bung hole that is diameter and eccentricity of bung hole then bung welding to get bung welded halves and then after joggling and buffing on upper half ; 10
(b) edge grinding of halves followed by footring welding;
- assembly of halves;
- buffing of the assembled halves;
- circumferential welding;
- tack welding on shroud with cylinder; 15
- dimensional and welding inspection of the cylinder followed by putting a serial number to the cylinder and batch number punching;
- normalizing temperature at 9000 ± 200 C;
- applying hydrostatic test at specified 6.57MPa test pressure;
- checking for no leakage in the cylinder body followed by shot blasting; 20
- zinc metalizing of the cylinders with required thickness;
- rolling of the cylinder on a rolling machine using steel balls to clean inside the cylinder;
- single coating of epoxy prime on the cylinder;
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- single coating of PU (Polyurethane) paint on the cylinder;
- taping of the bung followed by valve fitting; and
- air filling to the specified air pressure .
2. The method as claimed in claim 1, wherein thediameter of the circle cutting is 460 mm 5 and the thickness of the circle cutting is 3.7 mm.
3. The method as claimed in claim 1, wherein internal diameter and height of the halves are 226 mm and 198±2 mm respectively.
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4. The method as claimed in claim 1, wherein diameter and eccentricity of the bung hole are 52 mm and 2 mm respectively.
5. The method as claimed in claim 1, wherein total height of the cylinder is 506±10 mm.
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6. The method as claimed in claim 1, wherein the cylinder is a 13.6 litre or any other size or thickness refrigerant refillable gas cylinder.