Published on 13-Jan-2023

Vision Requirements in NDT

Vision Requirements in NDT

Author - Amit Gabani

When it comes to non-destructive testing (NDT), having clear and accurate vision is of the utmost importance. NDT technicians are responsible for inspecting and evaluating the condition of a wide range of industrial components, from pipes and structures to aircraft parts and turbine blades. This requires the ability to see fine details, detect small defects, and make precise measurements.

Here we discussed colour vision and near vision in this article.

Color vision acuity

One of the primary requirements for NDT technicians is that they must have normal color vision, as many NDT methods rely on color differences to identify defects. This means that those who are colorblind may not be able to perform certain types of NDT, such as fluorescent penetrant inspection or dye-penetrant inspection.

According to the American Society for Non-destructive Testing's (ASNT) Recommended Practice No. SNT-TC-1A, normal color vision is a requirement for all levels of NDT personnel. The standard states that an NDT technician must be able to distinguish among red, green, and yellow colors without confusion. This requirement is important because many NDT methods rely on color differences to identify defects, such as fluorescent penetrant inspection, dye-penetrant inspection, and visual testing.

To evaluate an individual's color vision, different tests can be used, such as the Ishihara test, the Farnsworth-Munsell 100-Hue test, or the Farnsworth Panel D-15 test. These tests are standardized, widely accepted and typically used by employers.

Near vision acuity

Another important requirement for NDT technicians is that they must have good visual acuity, or the ability to see clearly at a distance. This is particularly important for those who work with large or distant components, such as aircraft wings or offshore structures.

Some NDT methods also require the use of specialized equipment, such as video borescopes or digital radiography systems. In these cases, the technician must be able to operate the equipment effectively, which requires good visual acuity and the ability to focus on small details.

Again, according to the American Society for Non-destructive Testing's (ASNT) Recommended Practice No. SNT-TC-1A, near vision is one of the visual acuity requirements for NDT personnel. The standard states that an NDT technician must be able to read the Jaeger No. 2 test chart at a distance of 12 inches (30 cm) or the equivalent, with or without corrective lenses. This requirement applies to all levels of NDT personnel.

The Jaeger test chart is a standardized method for measuring near vision, consisting of a series of lines of progressively smaller print. The technician is required to read the smallest line that can be read comfortably, with no strain or difficulty.

It is also worth noting that some employer and some NDT methods may have more specific requirement. And in case of any vision problem, the employer might require a corrective glasses or other kind of aid. It's always better to check with the employer and the specific NDT method.

Depending on the employer and local regulations, certain eye exams and/or prescription may be required for the technician.

Overall, clear and accurate vision is a crucial requirement for NDT technicians, as it enables them to carry out their work safely and effectively. It's important for those considering a career in NDT to be aware of the vision requirements for the profession and to have regular eye check-ups.



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