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Raised Face Flange compared to Flat Face Flange

Raised Face Flange compared to Flat Face Flange

I'm trying to compare the dimensions of a CL150 raised face weld neck flange to a CL150 flat face weld neck flange.

As I am not very familiar with flanges, I am not sure if the dimensions of the two types are different (ie. inside/outside diameter, hub length, bolt circle diameter, flange thickness etc.)

In the ASME codes I am only able to find dimensions for "welding neck" flanges, but it is not specific as to whether the dimensions are for raised face or flat. Is it safe to assume that the dimensions are the same for both raised face and flat face flanges? (obviously excluding the 1/16" length of the raised face)

That is to say, if I were to machine off the raised face of a raised face CL150 flange, then would I be left with a flat face CL150 flange of correct dimensions (according to ASME B16.5)?


RE: Raised Face Flange compared to Flat Face Flange

The dimensions(ie. inside/outside diameter, bolt circle diameter)  of the two types are same except for the flange thickness and hub length. The flange thickness will now be reduced. See note 10 of the Table 9 in ASME B16.5 which states" When these flanges are required with the flat face, either the full thickness or the thickness with raised face removed may be furnished. Users are reminded that removing the raised face will make the length through the hub non standard. See paragraph, 6.3( provisions for acceptance of flat faced weld neck flanges) and 6.4.4(flange facing).

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668

RE: Raised Face Flange compared to Flat Face Flange

Thanks for your quick response, I really appreciate your help.
My copy of ASME B16.5 has a few pages missing, including the page with Note 10 of Table 9 and I didn't notice.

I would have still been lost without your help, thanks again.


RE: Raised Face Flange compared to Flat Face Flange

If you are analyzing Appendix "Y" flat face flanges you might want to go to my website then go to the Appendix "Y"
Flange Page. Here you can download a .zip file of a class 1, category 1 flange assembly written in MathCad. All you need to do is change the variables to match your geometry
and run the program. This should save you a couple hours of hand calculations.
Hope this is of some help.

Erie Shore Consulting Engineers, Inc.

RE: Raised Face Flange compared to Flat Face Flange


Thanks for your help, but when I click on the link to the file it requests a membership login with your username ( as the login.

How can I get around this?


RE: Raised Face Flange compared to Flat Face Flange

Try the download now. I might have inadvertently corrupted
one of the .html files.
Let me know if this works for you, if not I'll e-mail you
a copy.
Thanks for your patients.


Erie Shore Consulting Engineers, Inc.

RE: Raised Face Flange compared to Flat Face Flange

With due regards to "esce". Software must be verified and controlled to the satisfaction of the AI. Be careful.

RE: Raised Face Flange compared to Flat Face Flange

Thanks for the advice.
I took the info. from the ASME Code Appendix "Y"
line per line. Why would you think an AI would have a
problem with this?
I have verfied this software with numerous hand calculations. Need I do anything else? Any advice would be appreciated.

Erie Shore Consulting Engineers, Inc.

RE: Raised Face Flange compared to Flat Face Flange

Software Verification would probably come under your ISO manual [or your customer's] if they are to officially use it.

The Dutch Stoomwezen Code used to have a good section on software verification for Pressure Vessels.

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