OSHA’s PRCS standard defines the terms Blinding and Blanking in the same definition, but there is actually a difference between these practices. Here is OSHA’s definition:
Blanking or blinding means the absolute closure of a pipe, line, or duct by the fastening of a solid plate (such as a spectacle blind or a skillet blind) that completely covers the bore and that is capable of withstanding the maximum pressure of the pipe, line, or duct with no leakage beyond the plate.
Here are better definitions that explain the major difference in these practices:
