The act of determining the suitability of some material or component for its intended purpose using techniques that do not affect its serviceability.

Nondestructive testing (NDT) and Nondestructive Inspection (NDI) are terms sometimes used interchangeably with NDE and are generally considered synonymous. Nondestructive examinations are performed on weldments to verify that the weld quality

meets the specification, and to determine if weld quality is degraded during service.

Visual inspection should be the primary evaluation method of any quality control program. It can disclose flaws, signs of possible fabrication problems in subsequent operations, and can be incorporated in process control programs. Prompt and conscientious visual detection and correction of flaws or process deviations can result in significant cost savings, detecting continuities that would be found later by more expensive nondestructive examination methods.

All NDE methods must include the following to render valid examination results:

(1) A trained operator

(2) A procedure for conducting the tests

(3) A system for reporting the results

(4) A standard to interpret the results

The commonly used NDE methods that are applicable to the inspection of weldments are:

(1) Visual Inspection (VT) with or without optical aids

(2) Liquid penetrant (PT)

(3) Magnetic particle (MT)

(4) Radiographic inspection (RI)

(5) Eddy current (ET)

(6) Ultrasonic (UT)

(7) Acoustic emission (AET)

There are other NDE methods, such as heat transfer and ferrite testing, that are used for special cases. The considerations generally used in selecting an NDE method for welds are summarized in Table N-7. See also PENETRANT TESTING, MAGNETIC PARTICLE INSPECTION, METALLOGRAPHY, RADIOGRAPHIC EXAMINATION, and ULTRASONIC TESTING.

 

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