Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Mandatory Appendix-2-3 "G" value for O-Ring seal ?

Mandatory Appendix-2-3 "G" value for O-Ring seal ?

Mandatory Appendix-2-3 "G" value for O-Ring seal ?

When designing a flange with an O-Ring seal, which is 31" OD x 30.45" ID with a 0.275" C/S, should the "G" value be determined as stated in 2-3, or, should the "G" value = the OD of the O-Ring as noted in 2-5(c)(2).

If using the 2-3 definition of G, and assuming that "N" from table 2-5.2 is equal to the O-Ring cross section, bo =(0.275"/2)=0.1375", which is less than 1/4", so "G" = 30.725 (the mean Ø of the Contact face)


Should "G" = the Gasket OD = 31"

RE: Mandatory Appendix-2-3 "G" value for O-Ring seal ?

bayardwv, your reference to 2-5(c)(2) is confusing to me, I don't see the relevance.

I'd calculate G as per 2-3 and Table 2-5.2 (same thing). For your case. G = 30.725.

Maybe a point of interest, maybe not: Appendix Y which assumes essentially self energizing gaskets, defines G as the mean diameter; i.e. no consideration of effective width, b , bo, etc.



The problem with sloppy work is that the supply FAR EXCEEDS the demand

RE: Mandatory Appendix-2-3 "G" value for O-Ring seal ?

I agree, but several other co-workers believe that when using an O-Ring seal "G" is equal to "Go".
Please note my original post incorrectly stated 2-5(c)(2), it should have read, 2-5(c)(3)

To support their belief they reference the information in our PV Elite Software printouts that state that "G" = "Go" (Self Energizing)
and that 2-5(c)(3)(-a) reads..."The required bolt load for the operating conditions Wm1 shall be sufficient to resist the hydrostatic end force H exerted by the maximum allowable working pressure on the area bounded by the outside diameter of the gasket....
In addition it's been pointed out that Appendix 24, figure 24-1 shows "G" as the Outside edge of the O-Ring and not the mean diameter, as is shown for a flat gasket.
Basically I need to know what is the correct way to determine the value for "G" when using an o-ring seal on flange designed in accordance with Appendix 2.

I did sent an email to PV Elite support asking for clarification as to how they determine the value of G for self energizing seals.

RE: Mandatory Appendix-2-3 "G" value for O-Ring seal ?

bayardwv, OK I had not read that sentence earlier. It would seem to justify use of the OD. As a matter of convenience, and as use of the OD provides a more conservative result than use of "G", I'd go with the software.



The problem with sloppy work is that the supply FAR EXCEEDS the demand

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


White Paper – Your Construction ERP RFP Checklist
Selecting business software for a medium to enterprise-sized construction concern is extremely challenging in large part because most enterprise resource planning (ERP) suites originated in the world of repetitive manufacturing and are therefore a poor fit for a project and asset-centric business. However, midsize to large contractors need the predictable, auditable processes that ERP delivers. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close