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Status of manufacture of ultrasonic systems in India,
Paper published in The Journal of The British Institute of Non-Destructive Testing

This paper describes the status of manufacture and use of ultrasonic test systems within the Indian industry. Brief description of some of the indigenously built systems are included. The wide industrial application base and use of indigenous technology to build the systems are unique to the Indian manufactures.

Ultrasonic non-destructive testing technology has been in use in Indian industry from the late 50s. Earlier applications were mainly in the railways and steel industry. Over the years, the application of ultrasonic testing has been extended to virtually every known technologically feasible solution. Today, ultrasonic testing technology in India is widely used in testing of prime steel products (plates, shafts, profiles), railways (axles, rails, locomotive components), preventive maintenance (in nuclear, power plants, petro-chemical complexes, aerospace), foundries, forging shops, fabrication (pressure vessels, welds), pipe mills (ERW, seamless, SAW, spiral), research etc.

Due to the wide use of the technology the supporting industry has developed well. Indigenously-made high-quality equipments are available which comply with international specifications for test instruments. Through the Indian Society for Non-Destructive Testing (ISNT), the personnel training and certification code has been evolved to train the NDT professionals competently.

The NDT industry is very vibrant and has a large following. During the early days, the test results were questioned and doubts persisted in technological capabilities. In the present situation NDT is used as a tool to ensure equality, reduce costs and ensure reliable performance. It is very common to find NDT departments, to be independent in any production facility. Ultrasonic testing is one of the most widely used technology in the Indian indusry and its use is increasing with the advancement in technology and availability of newer equipments and solutions. Ultrasonic test systems have special relevance to the Indian industry in the present economic situation. More and more manufacturers put their products through on-line or off-line ultrasonic testing systems, to ensure equality of their products to be able to compete in the domestic or international market. With the growing requirements. the indigenous manufacturers of ultrasonic systems have development expertise in solving standard applications as well as finding customise solutions to meet specific test requirements. Critical to design and manufacture of ultrasonic test system is the engineering skills.

In India we have a large pool of expertise in electronics, computer related skills, fabrication and application engineering - which are essential for test systems. We have in India ultrasonic testing systems, small and large. simple and complex, fully engineered and manufactured indigenously. The advantages offered by locally produced systems in comparison to imported ones are: back-up service. low cost, effective customer training and customised engineering solutions, Some of the systems intalled in Indian industry are briefly explained in the following.
Automatic ultrasonic system for precision tubes

The system is designed for fully automtic operation at high test speed using an immersion technique for inspection of precision Zircally scamless tubes which are used in nuclear reactors (Figure 1), THe system detects defects in the order of 0.04 mm depth at surface speed of 2500 mm/s. with repeatability and stable operation. This high - performance system uses specially developed system components. The system integrates dimension measurement for wall thickness and diameter. A PC is used for tracking the tube and recording the test data. A range of customised test reports are generated. The system includes strip chart recorder, true to location marking and programmable sorting in three categories.

Welded pipe testing - SAW/ERW

The system shown in Figure 2 is developed and used for testing Spiral / Longitudinal weld seams of SAW and ERW pipes for detection of longitudinal and transverse weld defects. The system is designed for automatic operation with a paint marking facility to mark the defective area of the weld. A test report will be printed after each pipe is tested. Pipe under test travels under probe boom and alternatively the probes can traverse the stationary pipe surface to scan the entire lenght of the weld. The holding mechanism for probes is customised to suit the pipe mill requirements.
Automatic weld seam tracking system is provided on the probe boom to center the weld scam. at a fixed distance from the probes. A PC or a microprocessor is provided for defect logging and printing of test report. This system is designed to meet the requirements of several weld test specifications in general and in particular the API specification requirements. Inspections in heat affected zone and in areas near the weld are optinally tested by integrating additionally scaning probes. Optionally, pipe body test for lamination is integrated with suitable test mechanism. Reliable test operations are archieved and confirmed by coupling monitoring features integrated into the test electronics.

Plate testing system

The system is a 32-channel ultrasonic plate testing system for testing of plates for detection of lamination and other manufacturing defects which are oriented parallel to the test surface (figure.3). The system is designed with a PLC for automatic operation with a paint marking facility to mark along the linear edge of the plate corresponding to the defective area of the plate. A test report will be printed after each late is tested. This system is designed to meet the requirements of several plate test specifications, such as ASTM 435, BS 5996, SEL 072 etc.

Ultrasonic shell testing system

An eight-channel ultrasonic immersion testing system (Figure-4) has been developed for testing of hollow shell body for detection of manufacturing defects. Automatic monitoring of the test results, automatic sorting of the shells as per the set acceptance or rejection standards and print out of test result with defect details are the main features. Test mechanisms are fully automatic with robotic arm mechanism.


Ultrasonic piston bond testing equipment

The ultrasonic piston bond tester (Figure-5) is a fully automatic on-line equipment specially for checking lack of bond between the ring and piston body of a ring carrier piston. Length of the lack of bond and adjustable acceptance/rejection criteria, are established through microprocessor control.

Some of the other test systems in use are for inspection of seamless steel tubes, nodularity measurement in automotive test components. steel bar and rod testing, copper conductor testing, super conductor testing, bond testing in acrospace laminates. The test system use indigenously developed test electronics.

The test electronics are configured in single, multiple or parallel channels as suitable for the task. Some of the earlier systems used simple portable equipment duly modified and post processing of data was restricted to recording on strip charts and marking with paint the defective areas. The recent systems widely use microprocessor technology combined with PC and custom made software.

Test mechanics or material handling systems are custom made designed for the specific job requirements. Complex systens use PLCs to process the signals in co-ordination with the testing.

The test systems use one to several probes. At times probes are designed to meet the specific test requirements. Usually it is common to find specifically designed probes for test system. Focused immersion probe, immersion array probes and focused T/R contact probes are commonly used.

Even though the number of testing systems installed may be lower compared to other industrialised, the situation in India is unique due to its large application base in a variety of industries and extent of indigenous technology used. With the growing needs in test requirements, the demand for ultrasonic test systems is expected to grow, in existing production facilities and in newer applications. These needs will result in more challenging tasks for the manufacturers of ultrasonic test systems.
 
   
       
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