What do the letters at the beginning of an ASTM standard signify?

Every ASTM standard is identified by a unique designation. It includes a capital letter (A – H), followed by a serial number ranging from one to four digits, a dash, and finally the year of issue. For example, a common bolt specification is A449 – 07a, although when specified the standard’s year designation is usually not included.

The alphabetical letters represent general classifications. Outlined under each classification are a number of standards for a variety of products, materials, testing processes, and many other topics.

General ASTM Classifications

  1. Ferrous Metals
  2. Nonferrous Metals
  3. Cementitious, Ceramic, Concrete, and Masonry Materials
  4. Miscellaneous Materials
  5. Miscellaneous Subjects
  6. Materials for Specific Applications
  7. Corrosion, Deterioration, and Degradation of Materials
  8. Joint Committee and District Recipients

ASTM Letter Designations

Written March 19, 2008 by
Dane McKinnonDane McKinnon

Phone: 503.219.6991


    could you please tell , when to use ‘TYPE’ and when to use ‘Gr’

    For example, in case of SA 240 GR304 OR SA240 TYPE 304. I have seen both the designations. Is there any specific criteria?

    Expect your reply.

    @Ajith Kr – I do not believe that one or the other is correct nor incorrect, however in the ASTM A240 standard, the specific alloys are referred to as “Types”, so I believe that to be more common.

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