The coupling device is used to connect two rebar together at their ends for the purpose of transmitting the load which replaces the traditional way of lapping of rebars. Couplers do not normally allow disconnection of rebar. The main objective of couplings is to ensure quality in construction, less splicing time & substancial saving on the sacrificial steel rebar consumption due to replacement of lapping . By careful selection, installation and maintenance of couplings, substantial savings can be made in reduced maintenance costs and down time. In a more general context, a coupling can also be a mechanical splicing system that serves to connect the ends of adjacent parts or objects. As understandable from the concept it is highly technical in nature and it requires expert supervision, therefore there is a need of gratified service provider. One such group of an expert is Unitech Couplers India (P) Ltd.
Unitech Couplers India (P) Ltd is promoted by the United Group, specialized in manufacturing and exporting of Grey and Ductile Iron alloy castings. The group is headquartered in Coimbatore, predominantly an industrial city in Tamil Nadu, South India. The group consists of United Enterprises (UE) – The Exports Division, Technocast Foundry – The Manufacturing Division and Covai Metal Traders – The Heat Treatment Division. The Unitech Couplers Pvt Ltd company has two separate divisions. Machine shop where we have High Precision CNC machines in which we machine Automotive Castings and forgings and supply fully machined parts to Companies like Daimler Benz, FIAT, GM, Renault, Nissan, TAFE and many more MNC’s worldwide.
The other division of Unitech Couplers Pvt Ltd is the manufacture and supply of Rebar splicing parallel threaded couplers which manufacturers the machines, couplers in its ISO 9001 certified for Design and manufacture of rebar couplers with all In-house manufacturing and testing facilities. The products manufactured include Parallel threaded couplers and Threading services. They cater to the specific needs of construction of Infrastructure and building sectors in and around India.
Having branches at Ahmedabad, Bhopal, Chennai, Coimbatore, Cochin, Bangalore, Hyderabad, Vijayawada, Vizag, Mumbai, Pune, and Delhi (NCR) the company has so far completed more than 300 projects and ongoing of more than 50 projects across India. Unitech Couplers, is a Star Export House Certified by Ministry of Commerce, Govt of India for consistent Quality & export business. The group is always holding over 20 sets of machines and over 50,000 Couplers in stock in the factory for quick mobilization and capable of handling any big projects at quick time frame.
It is the 1st Indian company to get ISO 9001 certified for Design, Manufacture, and Supply of Rebar couplers and also certified by IS specified test labs – CSIR – Structural Engineering Research Centre, Chennai & IIT- Delhi, for Load test, High Cyclic Fatigue test, and Tensile tests.
Unitech Couplers is the only manufacturer in India with a manufacturing capacity of 2,00,000 couplers & having all testing facilities In-house (Scanner, Spectrometer, Tensile Testing, Pull Test, Profile projector, Impact testing, Hardness Testing, Gauging ,etc) using all Imported machines and Testing Equipment for manufacturing of Rebar couplers which are 100% inspected with traceability. They have established a niche for quality and client satisfaction through constant improvements in process and quality assurance and monitoring regimens and impeccable service. The raw materials for couplers are 100% tested by using the spectrometer at their lab. The couplers once machined are 100% verified using calibrated thread plug gauges. The threads on the rebar couplers produced at the site are again tested using the calibrated thread ring gauges. The threads on the rebar are protected from damages by using caps. And these caps are color-coded according to the sizes.
The Coupler System Features
ACI318-95 Clause 12. 14.3.4
A full mechanical splicing shall develop in tension or compression, as required, at least 125 % of specified yield strength of the steel bar.
BS8110Pt: 1997 Clause 184.108.40.206.2
The only form of full strength butt joint for a bar in tension comprises a me-chanical coupler satisfying the following criteria.
As per 1516172:2014, High cyclic fatigue Test to be conducted on the coupled rebars to know the actual quality & performance of joint on the long term when the load is applied. Also, Cyclic test, load test, slip test, and tensile test results are mandatory to meet the IS16172 standard.
When a test is made of a representative gauge length assemble comprising reinforcement of the size, grade, and profile to be used, and the coupler of a precise type to be used, the permanent elongation after loading to 0.6 fy should not exceed 0.1 mm.
Benefits of the system
- Cost Saving against lapping
- Continuity of Reinforcing bars
- No congestion of bars
- Construction cycle time reduced
- Steel wastage reduced
- Staggering of bars not required
- Dowels can be avoided enabling reuse of form works
- Allows full ductile elongation of bars
- No Torque wrenching required, Easy to install.
- Bar Cross section area is not reduced
Edge Cutting: The end of reinforcing bar is squarely cut by circular blade edge cutting machine for perpendicularity.
Press Forging (Cold Forging): The cut end of the reinforced bar is then forged by a cold forging process. The diameter of the bar is forged to a determined diameter thereby ensuring non-reduction of the no-minal cross-section area of the parent bar.
Thread Forming: Now the parallel threads are formed by the coiled rolled process at the end of the bars.
By doing this above process it adds about 7-10% of additional strength to the threads.
Unitech’s Edge of mechanical splicing system
Splicing of rebar using couplers has time-tested & proved for tremendous cost benefit, Time-saving & the quality in construction. Mechanical Splicing of Rebar is cost saving on steel consumption avoiding sacrificial steel wastages and has a Better load bearing due to the continuity of bars. There is no congestion of bars, thus avoiding honeycomb at the structural joints of both horizontal & vertical alignments. Moreover, it is easy to install and has a Faster splicing time when compared to Lapping of bars. The system allows full ductile elongation of bars. Discussed below are few of the advantages that Unitech provides in this regard.
- Increases the tensile and compressive capacity of columns, long columns and long beams where the designed tensile loading is greater than normal situations. Tension couplers are so far the best solution for tension columns and tension piles.
- Eliminates congestion of steel bars in heavily reinforced columns and core wall of the building. Thus reducing the formation of “honeycomb” in concrete structures.
- Facilitates speedier concrete casting, as bigger space between reinforcements facilitates an easier flow of concrete.
- Reduces cost and increases the speed of slip and jump formwork system in the construction of core walls and towers.
- Avoids strains, corrosion, and breakage of starter bars left for future extension of building and bridges.
- For the construction of structure like bridges in traffic congested area where the structure could be constructed in stages to allow the constant flow of traffic.
- Provide connections for starter bars for underground slab and beams in the construction of diaphragm wall to prevent breakage of precast starter bars during the process of bending up to avoid tedious concrete hacking.
- Where spacing between bars is insufficient to allow for lapping, e.g. in the construction of micro pile.
- Reduces the size of the concrete section and ensures maximum usage of expensive floor space in office towers.
- Enables connecting precast members to cast-in-site members, where a full tension splice is required.
The USP of Unitech System
- 1. Couplers: The group manufactures couplers strictly as per IS specification 16172 – EN8D steel. One single line manufacturing process for both export & domestic supplies.
- 2. Press Forging (cold Forging) System: Latest Technology in Mechanical splicing system across the Globe – PRESS forging & Parallel thread forming method using 3 rollers hydraulically pressed. With the technology innovation, parallel Thread rolling system, after cold press forging of ribs is better; since it adds 7% to 10% strength to threads due to compact micro structure formation.
- 3. Thread Forming Process: Company’s Press forging & Threading forming is a process by which; retains the Tempered Martensite layer (Hard tough tempered corrosion resistant layer) on the surface of the rebars on the thread portion. Further it will also maintain the Dia in both of the rebar & the threaded portion.
- 4.Threads: Unitech’s – “U” thread offers firm & more grip between the couplers & the threaded rebar being spliced, particularly when it is subjected to High Cyclic & Fatigue test.
The main objective of Unitech Couplers India Private Limited is to manufacture quality couplers and render threading services through expert supervision, at the site on time without hindrance to the client’s schedule at the site.
For further details:
UNITECH COUPLERS INDIA (P) LTD
M/s Unitech Couplers India Private Limited,
128/1, Vembadiyan Koil Steet, Arasur, Coimbatore – 641 407,TN, India
Tel: +91- 422-2901790 / Fax: + 91 422 2565733
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