A good NDE inspection program must recognize the inherent limitations
of each process. For example, both radiography and ultrasound have
distinct orientation factors that may guide the choice of which process
to use for a particular job. Their strengths and weaknesses tend to
compliment each other. While radiography is unable to reliably detect
lamination-like defects, ultrasound is much better at it. On the other
hand, ultrasound is poorly suited to detecting scattered porosity, while
radiography is very good.
Whatever inspection techniques are used, paying attention to the
"Five P's" of weld quality will help reduce subsequent inspection to a
routine checking activity. Then, the proper use of NDE methods will
serve as a check to keep variables in line and weld quality within
standards.
The Five P's are:
1. Process Selection - the process must be right for the job.
2. Preparation - the joint configuration must be right and compatible with the welding process.
3. Procedures - the procedures must be spelled out in detail and followed religiously during welding.
4. Pretesting - full-scale
mockups or simulated specimens should be used to prove that the process
and procedures give the desired standard of quality.
5. Personnel - qualified people must be assigned to the job.
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