: : Bharat Heavy Electricals Ltd. : :

Research & Development

Automatic Tube Butt Welding Machine
An automatic tube butt welder has been developed for joining tubes for high pressure and high quality applications. This machine uses TIG welding process with special controls to programme the parameters for automatic welding. This machine is also capable of MIG welding of tubes and pipes.

Twin wire CO₂ welding
A special purpose CO₂welding equipment was developed for welding of damper flapper blades to join 1.6 mm thick steel sheets to the hub pipe. The main feature of the equipment is the usage of two separate torches which draw power from a single power source.

Energy Saving Device for arc welding
It is a common knowledge that welding generators consume nearly 30% of the rated power during idle running which is non-productive. An Energy saving device has been developed by WRI to switch off the welding generator if idle running time exceeds a preset time.

Feedback controller for Resistance welding
A micro-computer based controller has been developed for sequencing and feed back control for effectively improving the quality of Resistance spot and projection welding.

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This controller automatically adjusts the current level against changes in work piece resistance to achieve the desired weld quality and nugget size. Preheat, post heat and multi impulse current programming are also provided. A microprocessor based hand held meter for the measurement of force and current during spot/projection welding has also been developed.
A stud welding controller was also developed for machines which are used to fabricate stud welded heat exchanger pipes. The controller is designed to ensure that the welding parameters are always within the range of optimized window which in turn will result assured weld quality.

Transistorised Power Source
Considering the advantages of electronically controlled power sources a transistorized power source of 400A capacity was developed for arc welding applications using MOSFET based secondary chopper. The salient features of this power source include better dynamic response, independent control of arc voltage and current, spatter free CO₂ welding, arc pulsing during MIG welding and easy adaptability for automation.

Engineering Services
Following engineering services have been offered to a number of fabricators and user – industries:

Prediction and control of longitudinal distortion to within +/- 5 mm over 14 m length and whole axis within +/- 1.5 mm in wind box assemblies of Power plants using Weld sequencing techniques

	Control of twist distortion within 3 mm with stringent requirements to restrict camber in box section column of tower type boiler structures
	Control of axis shift distortion in cylindrical and spherical shells by analyzing deformation kinetics using in-process multi-channel programmable strain data acquisition system to decide weld sequence.
	Residual stress measurements in
	CO₂absorber vessels to decide on the inter stage stress relieving heat treatment,
	Welded line pipes to device methods to minimize residual stresses,
	Bogie frames & torroidal rings to decide on the necessity for post weld heat treatment and
	Large welded structures to assess the stress level in as welded condition.
	Fatigue analysis of railway bridges, crane girders, locomotive bogie frames, repair welded hydro turbines, landing gear lugs, triplex chains and ball mill shafts.

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Testing and Inspection

WRI has offered testing services for a wide variety of customers in the following areas:

	Electrode testing for initial qualification and periodic surveillance as per AWS and BIS.
	Welding Power Source testing for static & dynamic characteristics
	Conventional mechanical, chemical, metallurgical and NDT tests on weld samples for qualification of welding consumables, welding procedures and welders.

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