What is the minimum light intensity required when performing VT, MT, or PT exams?

What is the minimum light intensity required when performing VT, MT, or PT exams?

• A. 50 foot-candles
• B. 150 foot-candles
• C. 100 foot-candles
• D. 200 foot-candles

Answer: (C)

Adequate visibility is essential for surface flaw detection in VT, MT, and PT. A lighting level of 100 foot-candles provides enough illumination to reveal small surface imperfections and penetrant indications clearly under typical inspection conditions, helping to avoid missed flaws or misinterpretation. If lighting were significantly lower, subtle cracks or porosity might go unseen; higher lighting isn’t required by this standard minimum, though it can be used if needed. Note that fluorescent penetrant testing uses UV lighting with its own intensity requirements, but for the general VT/MT/PT exams, the minimum is 100 foot-candles.

Adequate visibility is essential for surface flaw detection in VT, MT, and PT. A lighting level of 100 foot-candles provides enough illumination to reveal small surface imperfections and penetrant indications clearly under typical inspection conditions, helping to avoid missed flaws or misinterpretation. If lighting were significantly lower, subtle cracks or porosity might go unseen; higher lighting isn’t required by this standard minimum, though it can be used if needed. Note that fluorescent penetrant testing uses UV lighting with its own intensity requirements, but for the general VT/MT/PT exams, the minimum is 100 foot-candles.