Which statement about nondestructive testing methods is true?

Which statement about nondestructive testing methods is true?

• A. They always require destroying the part
• B. They can determine the size of discontinuities without damaging the weld
• C. They provide exact material composition
• D. They cannot detect surface defects

Answer: (B)

Nondestructive testing is all about checking quality without harming the part. A central point is that you can gauge how big a flaw is without damaging the weld. Techniques like ultrasonic testing or radiography can measure the depth or length of a crack or void, and surface methods such as dye penetrant or magnetic particle inspection can give you the size of surface-breaking flaws. This sizing capability is what makes NDT valuable for deciding whether a weld meets acceptance criteria without destroying it. The other statements don’t fit: destructive testing isn’t required for NDT, so it’s false to say they always destroy the part. NDT doesn’t provide exact material composition—that requires chemical analysis or metallography, not nondestructive inspection. And many nondestructive methods are specifically used to detect surface defects, so it’s incorrect to claim they can’t detect surface flaws.

Nondestructive testing is all about checking quality without harming the part. A central point is that you can gauge how big a flaw is without damaging the weld. Techniques like ultrasonic testing or radiography can measure the depth or length of a crack or void, and surface methods such as dye penetrant or magnetic particle inspection can give you the size of surface-breaking flaws. This sizing capability is what makes NDT valuable for deciding whether a weld meets acceptance criteria without destroying it.

The other statements don’t fit: destructive testing isn’t required for NDT, so it’s false to say they always destroy the part. NDT doesn’t provide exact material composition—that requires chemical analysis or metallography, not nondestructive inspection. And many nondestructive methods are specifically used to detect surface defects, so it’s incorrect to claim they can’t detect surface flaws.