Title of Invention	A PRESTRESSING STEEL STRAND FOR MANUFACTURING PRESTRESSED CONCRETE SLEEPERS
Abstract	An ingestible composition to prolong the useful life of an enteral feeding tube and a system of an enteral feeding tube and the composition is provided. The complete enteral feeding solution contains an edible antimicrobial agent which is 0.05% to 1.0% by weight alkyl paraben, the alkyl group having 1- 10 carbon atoms. Methyl, ethyl, or propyl paraben are particularly preferred

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The invention relates to a prestressing steel strand for manufacturing prestressed concrete sleepers. Due to the increased speed of trains in trunk roots of railway, the conventional wooden sleepers are being replaced by concrete sleepers. One of the major components of the concrete sleeper is the prestressed steel strand. The cost of the prestressing steel strand is about 40% of the sleeper cost. At present most commonly used prestressing steel strand is a three ply of three mm. To obtain the required prestressing force in the concrete sleepers, eighteen numbers of three ply three mm strands are required. Use of such large number of prestressing steel strands creates the following difficulties in the manufacture of concrete sleepers. The crowding of the steel strands along the cross-section of the sleeper provides operational problems during the manufacture of sleepers. The manufacturing of sleeper becomes labour intensive due to- the requirement of corresponding quantities of prestressing accessories such as grips, barrels etc, Further due to the large number of strands the scrap generation is also higher, The invention provides a novel prestressing steel strand which when used in the manufacture of concrete sleepers is economical and easy to handle. The prestressing steel strands according to the invention required for manufacturing a concrete sleeper with the required specific. is only eight numbers of seven ply. The difficulties encountered during the manufacture of concrete sleepers mentioned above are considerably reduced. Thus the invention provides a prestressing steel strand for manufacturing prestressed concrete sleeper comprising a seven ply steel consisting of a central core steel wire rod on which six steel wires are wound to form a spiraling layer covering the said central core steel wire rod, each of said steel wires being made of steel containing 0.78 to 0.83% by weight of carbon, 0.65 to .80% by weight of manganese, 0.15 to 0.30%, by weight of silicon, not more than 0.04% by weight of phosphorous, not more than 0.04% by weight of sulphur, not more than 0.10 % by weight of nickel and 0.8 to 0.15 % by weight of chromium. The invention will now be described with reference to the accompanying drawings : Fig. 1 shows the prestressing steel strand according to the invention. Fig. 2 shows the cross-sect ion of the steel strand shown in figure 1. The steel wires used for making the prestressing steel strand according to the invention is made of steel containing 0.78 to 0.83 % by weight of carbon, 0.65 to .80% by weight of manganese, 0.15 to 0.30%, by weight of silicon, not more than 0.04% by weight of phosphorous, not more than 0.04% by weight of sulphur, not more than 0.10 % by weight of nickel and 0.8 to 0. 15 % by weight of chromium. The prestressing strand is made by winding a spiral of six steel wires (1 to 6) on a core steel wire rod (7). Preferably the diameter of the core wire rod (7) is at least 1.5 times the diameter of the six outer wires (1 to 6) with equal diameters. Preferably the total diameter of the prestressing strand will be 7,5 mm t 5%. The ultimate tensil strength of the prestressing strand is 120 to 130 kg per mm. The steel wires used are drawn from high carbon steel having good stelmore cooled structure suitable for direct drawing without breakage. After stranding the seven wires the stress is relieved in a known manner. The prestressing steel strand according to the invention has preferably a minimum nominal tensil strength of 200 kgf/mm , minimum breaking load of 7000 kgf and minimum 0.2% proof stress of 5950 kgf. In order to make a prestressed concrete sleeper for railway lines which meets the requirement of a track used by high speed trains only eight prestressing steel strands according to the invention are required as re-enforcing elements in place of eighteen numbers of three ply three mm prestressing steel strands used at present. The following advantages are realised by using the prestressing steel Lit rands according to the invention when used for manufacturing prestressed concrete sleepers for railways. 1. Saving in the consumption of prestressing steel by 20% to 25%, compared to the present rate of consumption with 3 ply 3 mm PC strands. 2. Saving in operational cost and labour cost by reducing number of strands from eighteen numbers of 3 ply PC strand to eight numbers of 7 ply PC strand. 3. Reduces the consumption and the cost of prestressing accessories and labour cost proportionately. 4. Due to use of only eight numbers of PC strand, the concrete strength improves due to higher concrete aggregate. My co-pending Indian application no. /MAS/99 filed along with this application titled "A prestressed concrete sleeper for railway lines", use the prestressing steel strand according to this invention. I CLAIM : 1. A prestressing steel strand for manufacturing prestressed concrete sleeper comprising a 7 ply steel consisting of a central core steel wire rod (7) on which six steel wires (Ito 6) are wound to form a spiraling layer covering the said central core steel wire rod (7), each of said steel wires (1 to 6) being made of steel containing 0.78 to 0.83% by weight of carbon, 0.65 to not more than 0.04% by weight of phosphorous, not more than 0.04% by weight of sulphur;, not more than 0.10 % by weight of nickel and 0.8 to 0.15 % by weight of chromium. 2. The prestressing steel strand as claimed in claim 1, wherein the diameter of each of the six steel wires covering the central core wire are equal and the diameter of the central core wire is at least 1.5 times the diameter of each of the said six steel wires covering the central core wire. 3. The prestressing steel strand as claimed in claims lor 2, wherein the diameter of the 7 ply prestressing steel strand is 7 . 5 mm ±, 5% . 4. The prestressing steel strand as claimed in any one of the previous claims, having minimum a nominal tendril strength of 200 kgf/mm minimum breaking load of 7000 kgf and minimum 0.2% proof stress of 5950 kgf. 5. A prestressing steel strand for manufacturing prestressed concrete sleeper, substantially as hereinabove described and illustrated with reference to the accompanying drawings.

Documents:

256-mas-1999-claims filed.pdf

256-mas-1999-claims granted.pdf

256-mas-1999-correspondnece-others.pdf

256-mas-1999-correspondnece-po.pdf

256-mas-1999-description(complete)filed.pdf

256-mas-1999-description(complete)granted.pdf

256-mas-1999-drawings.pdf

256-mas-1999-form 1.pdf

256-mas-1999-form 26.pdf

256-mas-1999-other documents.pdf