To my knowledge the ISO flange ratings are 16, 25, 40, 64 and so on. PN 20 or PN 50 are not ISO ratings.

Thanks micalbrch

If I understand correctly, PN 16 (CWP=232 psi) and lower flanges can be used on ASME Class 150 (CWP=275 psi) Valves. PN 25 (363 psi) & 40 (580 psi) on ASME Class 300 (CWP=720 psi). PN 64 (CWP=928 psi) on ASME Class 600 (CWP=1480 psi)...
What DIN Standard specifies the valve wall thickness based on PN pressure rating?

In addition, do PN ratings meet Face to Face dims of equivalent ASME Classes?

Have a look in the attached pdf file. There you can see what ISO flange fits to what ANSI flange size. I know that some fit just face to face and some don't.

 

• http://files.engineering.com/getfile.aspx?folder=df970387-23c2-47b9-a513-c8

Awesome micalbrch thx. What DIN Std would specify Face to Face?  

There is no DIN or ISO standard which specifies the face to face matching. Some ANSI and ISO flanges just match each other and some don't.

How are DIN Valves Designed if no Face to Face Std exists by PN rating?  

BS-EN1092-1:2007; 'table17-Dimensions of PN100 Flangs' invokes Annex J for Flange Dimensions on sizes DN400 & 500. However, Flange Thickness (C3) is not included in Annex J. Does thickness require calculation? If so, please provide Standard for Calculation Method (Is it comparable to B&PVC VIII Div1 APP.2?)  

ISO-7005-1 provides dimensions for PN 20 and PN50 flanges.  They are equivlent to ASME class 150 and 300 respectively.  In order to make an international standard, ISO needed to include the ASME flange dimensions since they are used in over 50% of industry globally, so PN 20 and 50 were created.  But they are just ASME 150 and 300.

Face-to-face discussions, I am not answering because you are talking two different subjects.  One is mating of flanges, and the other is the overall length of valves.

Thanks for all the feedback.