Flaw detectors. During the manufacturing process of anything made of metals, imperfections sometimes occur. Some of them are allowed in the finished products if they are sufficiently small. However, cracks are never allowed regardless of their size because they have a tendency to grow under applied mechanical stresses.
During his first year with the Research Institute that developed flaw detectors, one of founders of SF Industries, Inc. Peter Shapiro invented a flaw detection system for petroleum pipes and tubing which is still the most superior in the world.
The same electronic equipment that was originally developed for the petroleum industry is now used to detect cracks in aircraft structures, especially under rivets. This project is under development.