What are standards?
Standards are documented agreements containing technical specifications
or other precise criteria to be used consistently as rules, guidelines,
or definitions of characteristics, in order to ensure that materials,
products, processes, and services are fit for their purpose.
For example, the format of the credit cards, phone cards, and
"smart" cards that have become commonplace is derived
from an ISO International Standard. Adhering to the standard,
which defines such features as an optimal thickness (0.76 mm),
means that the cards can be used worldwide.
An important source of practice codes, standards, and recommendations
for NDT is given in the Annual Book of the American Society
of Testing and Materials, ASTM. Volume 03.03,
Nondestructive Testing is revised annually, covering acoustic
emission, eddy current, leak testing, liquid penetrants, magnetic
particle, radiography, thermography, and ultrasonics.
There are many efforts on the part of the National Institute
of Standards and Technology (NIST) and other standards organizations,
both national and international, to work through technical issues
and harmonize national and international standards.