A technical seminar on NON-DESTRUCTIVE TESTING IN RAILWAYS Presented by N.SUDHEER M.TECH(MACHINE DESIGN) 16481D1509 GUDLAVALLERU ENGINEERING COLLEGE Sheshadri Rao Knowledge Village, Gudlavalleru, PIN: Presented by N.SUDHEER M.TECH(MACHINE DESIGN) 16481D1509 GUDLAVALLERU ENGINEERING COLLEGE Sheshadri Rao Knowledge Village, Gudlavalleru, PIN:521356

Introduction: Amongst the different modes of transport, Railways have their greatest utilization in the transport of large volumes of heavy and bulk commodities and passengers over long distances with safety, comfort and convenience. So railroads require constant support to maintain their integrity and operate safely.

Role of Non-Destructive Testing(NDT) in Industries: NDT is widely used in industries for : Verification of design quality, Certification of manufactured products, Assessment of product degradation, and Effective repair or replacement during service. NDT has also been a valuable tool in risk assessment based on experience.

A number of railway components and assemblies are tested and evaluated using NDT methodologies, during manufacture for freedom from unacceptable defects and anomalies. The major components subjected to various NDT methods are: Rails, Wheels, Axles, Bearings, Welded rail joints, and Brides, etc.

Rail inspection is the practice of examining rail tracks for flaws. Non-destructive testing (NDT) methods are used as a preventive and/or predictive measure against track failures and possible derailment. Methods used to detect flaws in rails: Visual Examination(VE) Ultrasonic Testing (UT) Eddy Current Testing (ET) Magnetic Particle Inspection (MPI) Radiographic Testing (RT) Electromagnetic Acoustic Transducer (EMAT)

Rails Rails are the members of the track laid in two parallel lines to provide an unchanging, continuous and level surface for the movement of trains. To be able to withstand high amount of stresses these are made of high carbon steel(HCS).

Fig: Rails

Fig: Manufacturing of Rails

Fig: Cross section of Rail

Defects in rails Piped rail Bolt hole cracks Head and web separation Foot and web separation Horizontal and Vertical Split Web Defective Welds Rail Corrosion

Fig: Piped Rail

Fig: Bolt hole cracks

Fig: Head and Web Separation

Fig: Horizontal split head

Fig: Defective welds in rails

Fig: Corroded rail

Visual Inspection/Testing(VT) Non-destructive rail testing procedure usually starts with a visual inspection: With the naked eye and supported with mirrors, Magnifying glasses, and Artificial light sources experts can recognise exactly which testing methods should be used.

Fig: Visual crack on rail

Ultra sonic Testing(UT) of Rails Ultrasonic Testing (UT) is a non-destructive inspection method that uses high frequency sound waves (ultrasound) that are above the range of human hearing, to measure geometric and physical properties in materials. Ultrasound travels in different materials at different speeds (velocity). However, the speed of sound propagation in a given material is a constant.

Steps in Ultra sonic Testing Surface preparation, Calibration, Conduct examination, and Interpretation of results.

Irregularities in material and internal faults can be detected by the ultrasonic testing method. In the process, areas of the rail that are subject to faults can be checked through the various angles of incidence and probe heads.

Fig: Ultra sonic Testing

Fig: Ultra sonic single-rail tester

Fig: Portable Ultra sonic double rail testing equipment

Fig: Ultra sonic rail testing truck

Eddy Current Testing(ET) Eddy current inspection uses the principal of “electromagnetism” as the basis for conducting examinations. Eddy currents are created through a process called electromagnetic induction..

When alternating current is applied to the conductor, such as copper wire, a magnetic field develops in and around the conductor. This magnetic field expands as the alternating current rises to maximum and collapses as the current is reduced to zero. If another electrical conductor is brought into the close proximity to this changing magnetic field, current will be induced in this second conductor.

Fig: Principle of Eddy current Testing

Steps in Eddy current Testing Setup equipment, Calibrate instrument, Calibrate probe, Inspect for indications, and Monitor the readings.

Fig: Eddy current Testing

Magnetic particle Testing(MPT) MPT uses magnetic fields and small magnetic iron filings to detect defects in components. The only requirement is that the component being inspected must be made of a ferromagnetic material such as iron, nickel, or some of their alloys. Ferromagnetic materials are those that can be magnetized to a level that will allow the inspection to be effective.

Steps in Magnetic Particle Testing Prepare the part surface, Apply the magnetizing force, Dust on the dry magnetic particles, Gently blow off the excess powder, Terminate the magnetizing force, Inspect for indications, and Resetting the magnetisation.

Fig: Magnetic Particle Inspection

Fig: Automated quality control system for rails

Wheels and Axle A train wheel or rail wheel is a type of wheel specially designed for use on rail tracks. An axle is a central shaft for a rotating wheel. A wheel set is the wheel - axle assembly of a railroad car(locomotive). Wheels are cast or forged (wrought) and are heat-treated to have a specific hardness.

Fig: Single flanged rail wheel

Fig: Double flanged rail wheel

Fig: Contact between wheel and rail

NDT for wheels and axles Ultra sonic inspection, Magnetic particle inspection, Radiography, and Thermography.

Fig: Ultra sonic inspection

Fig: Ultrasonic Testing on Wheel Set Axles-Probe Head

Fig: Ultra sonic inspection of railway wheels for horizontal position

Fig: Ultra sonic inspection of rail wheels for vertical position

Fig:Fully automated System for Magnetic Particle Inspection of Railway Wheels

Fig: Wheel-test line-Complete rail-wheel handling, testing and measuring system including hardness, laser dimensions, ultrasonic and magnetic examination

Fig: Robotics-assisted thermography at a rail wheel

Themographic image of railway bridge

Fig: IR Thermography (Thermal Imaging Cameras Monitor Overhead Lines) in Railways

Conclusion Non-destructive testing (or) NDT is the use of non- invasive techniques to determine the integrity of a material, component or structure. These techniques allow for inspection without interfering with the specimen’s final use. NDT has a wide range of applications in industries. Especially in railway industries, various NDT techniques such as visual examination, ultra sonic testing, eddy current testing, magnetic particle testing, and thermography, etc., plays a vital role to inspect and monitor the condition of infrastructure effectively.

References Applications of NDT in rail track - Lee Guan Bin (Nanyang Technological University, School of mechanical and aerospace engineering). Detection and evaluation of rail defects with nondestructive testing methods Anika Dey 1, Jochen Kurz 2, Lukasz Tenczynski 3. Hand book of non destructive evaluation – Charles Hellier (Mc Graw-Hill publishers).

THANK YOU