ASME Standards for the Revision of Engineering Drawings

Updated on January 8, 2018
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Tamara Wilhite is a technical writer, industrial engineer, mother of two, and a published sci-fi and horror author.


American Society of Mechanical Engineers standard ASME Y14.35M was issued in 1997 to describe the ASME approved format for tracking revisions and other changes to engineering drawings. ASME Y14.35M was reaffirmed in 2003, and no changes were made at that time. It updated to the name ASME Y14.35 in 2014.

What does ASME Std Y14.35 mandate?

ASME has issued standards for the proper documentation of drawing revisions.
ASME has issued standards for the proper documentation of drawing revisions. | Source

ASME Y14.35M Standard

ASME Y14.35M and the later ASME Y14.35 standard allows for changes to be made to drawings by adding and crossing out information on a drawing or by creating a new drawing revision.

The ASME drawing standards state that new drawings can be recorded as a new revision letter or as a new drawing number that supersedes the old one. The replaced drawing will be modified to note “replaced with change by drawing 1234567”. This ensures configuration management and product verification is handled correctly.

The first version of a drawing is identified by a revision dash “-“. After that, revision letters are used. Revision letters can be a single letter up to multiple letters.

All letters can be used as revision letters except I, O, Q, S, X and Z. These letters are not allowed because they can be mistaken for numbers or for other letters. For example, a revision letter I can be mistaken for a 1 while an S can be mistaken for a 5. Revision letters must also be uppercase, to minimize confusion between a lowercase "l" and "1" and "I".

After the end of the revision letter sequence is used up, the next letter is added to the end. Revision letter Y is followed by revision AA. Revision AY is followed by BA. Revision DY is followed EA.

However, revision letters are not allowed to exceed two characters, so there is no revision greater than YY. At this point, you should issue a new drawing number.

Revision columns are located in the upper right corner or next to drawing the title block. Revision columns include the revision letter of the drawing, a short description of the changes made between this revision and the prior one, and the date the revision was made or the revised drawing was approved. Revision columns frequently include the drafter who made the latest revisions.

ASME standards require parts to be labeled with the part number and revision letter per their manufacturing drawings.
ASME standards require parts to be labeled with the part number and revision letter per their manufacturing drawings. | Source

Related Standards

ASME standard Y14.24 gives readers a list of when ASME engineering drawing standards like ASME Y14.35 apply. ASME Y14.1 defines the acceptable form of the revision history block.

ASME Y14.1 gives the ASME standard size and format used in engineering drawings.

ASME Y14.2 outlines the accepted line conventions and lettering used on engineering drawings. ASME Y14.3M describes the accepted forms of single, multiple and sectional views used on engineering drawings.

ASME Y14.100 provides a list of standard engineering drawing practices recommended by the ASME. Depending on the customer or project, other ASME or ISO standards may also be required. And ASME drawing standards do not cover documentation control or configuration management at all.

Questions & Answers

  • Is the ASME standard rev1 or should it be REV1 when naming the file?

    I've seen it written as both "Rev" and "REV".

  • Do the revised standards of engineer drawings allow skipping item numbers in a bill of material?

    Yes. You could have item 1, item 2, and item 4. You can avoid confusion for the reader by listing item 3 and having an obvious place holder dash in the BOM. Then it could be filled in as part of a later version of the BOM.

  • If I have a multi-page page document and rev sheet 1 and 4, do I update rev of all?

    Short answer: yes, at least the title block.

    Long answer: all document pages should refer to the same revision letter and version number so that people who are looking at a set of drawings know that they belong together.

  • What is the release date for the Asme Standards?

    A release date is a date you officially release or publish the drawing. The release dates of drawing revisions show when the new drawing version is official. Anything built after that point typically has to be made to the new revision.

  • What is the standard practice when the revision block is full (i.e. 5 lines) and the print is too small to add more rows?

    I suggest referring directly to ASME Y14.100 for the solution.


Submit a Comment
  • Garry Reed profile image

    Garry Reed 

    5 months ago from Dallas/Fort Worth, Texas

    Interesting. I was an on-the-board drafter for many years back in the olden days and all changes to defense system drawings where executed by ERs (Engineering Requests) and EOs (Engineering Orders) if my poor old brain remembers.

    Even during modern times as a tech writer and logistics specialist doing all work via computer programs I had to stay abreast of drawing changes and pending changes, and as a logistics engineer even recommended some of those changes myself.

  • tamarawilhite profile imageAUTHOR

    Tamara Wilhite 

    5 months ago from Fort Worth, Texas

    I don't know how to handle documention within SAP.

  • profile image


    5 months ago

    I have a question: Can a description be changed in SAP system only adding dimensions to description without creating an ECO. No change is being made to the drawing or title block. Drawing title: Label, description in SAP- Label. When looking for a label drawing in the system( shouldn't they have dimensions in the description to make it easier to locate what your looking for? Question is: Can you add to the description without writing and ECO on an active part number.

  • tamarawilhite profile imageAUTHOR

    Tamara Wilhite 

    15 months ago from Fort Worth, Texas

    Update the most recent released drawing to the next revision letter.

  • profile image

    James R Dunn 

    15 months ago

    I have a question about revisions. I recently found a drawing from my company that has the same revision letter used twice. What is the proper way to handle this mistake?

  • tamarawilhite profile imageAUTHOR

    Tamara Wilhite 

    22 months ago from Fort Worth, Texas

    MZ1 Form what I've seen, they use the same symbols for drawings. However, concentricity and symmetry differ. ISO uses geometric tolerancing and doesn't recognize that used by the ASME standards.

  • profile image


    22 months ago

    Hello Tamara

    Our company is certified lately to AS9100 standard

    I’m looking for a linkage between:

    ASME Y14.35M rules



    I mean where should I find the ASME Y14.35M rules in AS9100 ?


  • tamarawilhite profile imageAUTHOR

    Tamara Wilhite 

    2 years ago from Fort Worth, Texas

    The "M" refers to metric version of standards like the older version of ASME Y14.34M; the "M" disappears when metric and non-metric standards are consolidated.

  • Steel Engineer profile image

    Steel Engineer 

    5 years ago from Kiev, Ukraine

    Worthwhile read. Thanks for sharing this.


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