What non-destructive inspection method can measure the wall thickness of closed vessels? a) Radiographic method b) Ultrasonic method c) Fluorescent penetrant method d) Magnetic particle method

The ultrasonic method is quite popular for measuring the wall thickness of closed vessels. It uses high-frequency sound waves that travel through the material, reflecting off any flaws or changes in thickness. This method is highly effective, as it can provide precise measurements without causing any damage to the vessel, making it a favorite in various industries such as oil and gas, aerospace, and manufacturing. Radiographic methods also come into play for assessing internal structures within closed vessels. X-rays or gamma rays can penetrate materials, producing images that reveal the thickness and integrity of the walls. However, they often require specialized equipment and safety precautions due to radiation exposure, making them more complex to use than ultrasonic techniques.