Re: what is... Perhaps this question is not as simple as it may sound. English is full of subtlties in language (e.g. "should" and "shall" are often not noted as different when translated outside of English). As well, specific technical implications do not always have the same meaning in English and American (not to mention spelling!).
I provide below a heirarchy of the document types that are asked about. To the list I have added "procedure" and "technique" which are also sometimes used with different or inter-changeable meaning. Others may have slightly different notions of the meanings of these words.
The terms "code", "standard", "specification" and "procedure" are often confused in NDT. In some cases these terms are used inter-changeably. However from a technical point of view each refers to a separate type of document. To avoid even further confusion we will restrict our definitions to the written documents implied by these terms. This caution is due to the common referral to calibration blocks or test pieces with known defects used to verify accuracy of a test procedure as a "standard".
A standard is a written document assembled by recognized experts, with the purpose of recommending actions to achieve certain objectives. An example of a standard is the American Society of Nondestructive Testing Recommended Practice No. SNT-TC-1A. This is a standard for qualification and certification of NDT personnel by employers.
A standard is usually enforced or given authority by an organization or agency (typically professional societies or national institutions). When a set of standards is incorporated into law and thereby enforceable legally it is considered a code. Examples of codes are:
-American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code
-Canadian Standards Association (CSA) Z662 Oil & Gas Pipeline Systems.
When a user or purchaser of a specific product requires assurance of quality level they will often arrange their own document describing specific test parameters and acceptance criteria. Such a product specific standard is considered a specification. Although it may reference other codes and standards it can require more stringent limits than the more general standards.
To avoid the ambiguity of the usually general standards, and to avoid the constant updating of specifications that refer to national standards which are constantly revised, companies often develop a procedure.
The procedure can address the company's needs by setting out its standard practices for the various aspects of the test method, such as; procurement, processing, periodic controls, approved materials and accessories.
Finally, as a contracted inspection company applies a test to various parts, the variations available to achieve the desired results can be too myriad to list as part of the procedure document and generalisations are again too vague. A common method of addressing the specific inspection application to a specific part is to use a technique sheet.
: please tell me 1 what is a code? 2 what is a standard? 3 what is a specification? 4 what is defference between a code a standard and a specification? best regards