The future is NDT: NON-DESTRUCTIVE TESTING
NDT (non-destructive testing) refers to an array of inspection techniques that allow inspectors to collect data about a material without damaging it. Also referred to as NDE (non-destructive examination or evaluation) and NDI (non-destructive inspection), it is a non-intrusive procedure for gathering data about a material, system, or component without permanently altering it.
While the technology has been around for some time, in Sri Lanka, there are very few services that offer this type of testing with just a handful having popped up in the recent past.
One such organisation that offers NDT in Sri Lanka is Lanka High Tech Marine (Pvt.) Ltd. Its Founder Shanthilal Rathnayake shared with us the benefits of NDT and the many avenues it opens up in terms of industrial safety, quality assurance, and more.
The company currently carries out the following services: Hull thickness gauging (IACS), NDT (RT/UT/PT/MT/VT/LT), pre-shipment inspection (DGFT India), annual throughput examinations (Labour Department regulation), bunker hose testing (ISO 1402), and oil spill response (NOSC regulation).
What is NDT?
Rathnayake stated that, to begin with, it must be made clear that NDT does not necessarily require the use of special tools, or any tools at all. He shared that, for instance, when inspectors in industrial settings review the outside of a pressure vessel with their naked eye, that too would fall under the category of NDT, since they are collecting data on the status of the boiler without damaging it. On the other hand, using a sophisticated tool like an ultrasonic sensor to look for defects in a certain material or asset would also be called NDT.
“Whatever the specific use case may be, the underlying commonality among all these examples is the collection of data in a non-intrusive manner,” he said.
He shared that prior to the development of NDT, most commonly used mechanisms included destructive testing, i.e. methods used to test materials that alter or even damage and destroy the materials tested. This is where a piece of the material might be scraped away for analysis or altered in some way onsite.
An example is macro sectioning, which involves testing a small section of a welded material by polishing and etching it for examination. Then, there is tensile testing, where we use controlled tension applied to a sample material to see how it reacts, often to test a material’s failure point; and also three-point bend testing, which examines the soundness and flexibility (or ductility) of a material.
NDT testing includes ultrasonic NDT (UT), radiography NDT (RT), eddy current NDT (ET), magnetic particle NDT (MT), acoustic emission NDT (AE), liquid penetrant NDT (PT), and leak testing (LT).
Rathnayake shared that they commonly use UT in their practices. It is the process of transmitting high-frequency soundwaves into a material in order to identify changes in the material’s properties. He shared that UT uses soundwaves to detect defects or imperfections on the surface of a material.
Why is it important to adopt NDT?
Rathnayake shared that there are numerous reasons why NDT is simply more beneficial than any other type of testing we currently utilise.
Speaking on the financial benefits, he stated: “This is the most obvious reason. NDT is more appealing than destructive testing because it allows the material or object being examined to survive the examination unharmed, therefore saving money and resources.” He added that it is as simple as that, and considering this, it is a no-brainer to facilitate the introduction of this type of testing into the market on a wider scale.
He said that it is also far safer, adding that almost all NDT techniques, leaving out radiographic testing, were harmless to people. There is no risk of injury. It is also incredibly efficient, said Rathnayake, as it allows for the thorough and relatively quick evaluation of assets, which can be crucial for ensuring continued safety and performance on a job site.
Finally, it is accurate. NDT methods have been proven to be accurate and predictable. When it comes to quality assurance and maintenance procedures that are meant to ensure the safety of personnel and the longevity of equipment, this level of unwavering accuracy is required.
He shared that NDT is essential for a well-run facility. However, how aptly the service is used depends on highly trained technicians with experience and integrity. Industrial NDT methods and interpretation of results are done by certified professionals. Rathnayake shared that not only does the technician need to be certified in a specific NDT method, they also need to know how to operate the equipment being used to gather data.
NDT in Sri Lanka
He pointed out that when it comes to acquiring these accreditations and certifications, however, there are certain concerns in Sri Lanka, primarily because there is no dedicated authority for its regulation. He said that at present, what we have is the Sri Lanka Atomic Energy Board, which is under the Ministry of Energy. He added that it would be beneficial if this authority could be made more accessible, as it is currently limited, thereby affecting the potential expansion of NDT in the island.
Speaking about the necessary certifications, he said that in order to carry out NDT testing, one must acquire a certification given by the American Society for Nondestructive Testing (ASNT), for which there are three levels. Level I is where one is qualified to perform specific calibrations, specific NDT, specific evaluations, and record results. Testers with this level of certification should receive specific instruction or supervision from an NDT Level II or III certified tester.
Level II testers are qualified to set up and calibrate equipment and interpret and evaluate results as per applicable codes, standards, and specifications. They should be familiar with technical limitations and exercise assigned responsibility for on-the-job training and guidance of trainees and Level I personnel.
“However, in order to train a Level II tester, we must have a Level III qualified person, who is required to develop, qualify, and approve procedures, establish techniques, and interpret codes and standards. They should have sufficient practical background in applicable materials, fabrication, and product technology,” he shared.
In Sri Lanka, only two Lankans are qualified as Level III personnel, and one of them is no longer serving in the country. The one who is remaining works for SriLankan Airlines. As such, there is a problem when it comes to expanding the service on the island.
Rathnayake also stated that, as a private company that is entirely based in Sri Lanka, it has been disheartening to experience the numerous obstacles presented to them by the local authorities, “especially the (Sri Lanka) Ports Authority”, Rathnayake shared, adding: “For our work, we have to access the harbour, as our services are often sought by the ships that enter the dockyard. However, we have to acquire multiple levels of clearance to enter; whereas Indian companies have smooth access even with tourist visas.” He said that there have been occasions where they were delayed and missed business opportunities because the port authorities delayed clearance.
“Only 20% of the ships that come to the dockyard are serviced by Lankan companies. Everything else is attended to by foreign companies, which is unfortunate,” he said.
He provided that while NDT is a relatively new concept to Lankan industries, it is a significant element in production, maintenance, safety, and quality, and therefore he only hopes that the relevant authorities could look into the current regulations in place and make the necessary allowances so that the technology can be widely accessible.