Pressure Rating for Flanges as per AWWA and ANSI

• PN 10 and PN20 are flange detail designs - pitch circle diameter, bolt size and number, etc..
• The class is a pressure rating that varies with temperature.

That is the difference.

It's rather the reverse of that: PN = nominal pressure in bars inside a pipe; flange Class number indicates the flange dimensions. They don't correlate very clearly, hence there is confusion. Depending on temperature, allowable flange pressures are sometimes above and sometimes below their class designations.

In case of AWWA flanges temperature is ambient temperature and 150 class flange is for 10 bar nominal pressure (PN 10) where as in case of ANSI flanges 150 class flanges is indicative of 20 bar (PN20)....which may be for higher temerature...but pressure limits are lesser at higher temperature..it is not understood...

Srijit.

excellent response, you are a great teacher. Best regards.

Edgar

Dear Edgar,

Thank you for the comments.

If you believe in perfection, that is one of the ways to winning situations.

Good luck to you.

Best Regards,

Srijit

Thank you Mr Srijit, Really very good answer and it clears my doubt......

While I realize no offense is likely intended, and there is indeed clearly lack of understanding, incomplete inquiries on blogs as well as answers to same can unfortunately enforce inaccurate perceptions. In this regard, the OP has not really provided any actual American or ISO etc. "standards" to be compared for most proper response, but has only provided only the acronyms for standards organizations "AWWA" and ANSI" and then thrown in some reference to "150#" and "PN" to further muddy the water. That unfortunately relegates future responses to primarily guesswork, as to what is really needed. While I believe at least one responder has perhaps provided a hint of what a potential answer to the real question is i.e. the scope of the standard involved that may define e.g. criticality of service, and ranges of temperature and other exposures etc. that can be extreme in some applications, they also imply necessary distinction between ANSI and AWWA that is frankly not there in some cases, and they also say that AWWA is only for "portable" water. Actually, the scope of many now actually combined ANSI/AWWA specifications includes not only potable water, but other water applications as well e.g. wastewater and reclaimed water etc. and many questions can be answered by the inquirer first reading the appropriate latest version of the ANSI/AWWA etc. or ISO etc. standards involved, beginning with the front matter. It should be understood as well that both AWWA and ANSI have roots going back many decades (AWWA actually more than 100 years w/ NEWWA etc.) with initial applications and involvement/transitions including early piping materials such as gray cast iron, whereas some ISO standards are newer and may include only more recently developed, stronger etc.piping materials.