Hi guys,

Could any of you out there assist me with an issue that I have which is bugging me?

The issue I have is regarding flange evaluation and flange leakage in CII. I know there are numerous post out there about this issue but I have never come acrossed one which clearly outlines it. Hence, my little query out there to you guys...

In CII, there is the flange evaluation method which adopts the usage of the Kellog's Pressure Equivalent Method and ASME III's Nuclear Code subsection NC-3658. For flange leakage/stress calculations, CII has adopted the ASME VIII method.

Here is where I would like to be corrected if my approach towards this issue is incorrect and be advised accordingly. My understanding is this.

With the flange evaluation approach, all CII is telling us is that by selecting either method of calculation, we will be able to determine the impact of the internal pressure, external forces and bending moments and comparing that against either the B16.5 flange rating table or the yield strength of flange material at design temperature. Hence if the flanges were to fail, potential leakage may occur...

As with the ASME VIII method, flange damage and gasket damage may occur if the operating condition stresses and gasket seating stresses are above the flange yield stress at design temperature or installation temperature respectively taking into account of all the flange parameters. However, this method does not take into account the effects of external pressure and external forces and moments from the piping. Nevertheless, if the flanges were to be overstressed, potential leakage may also occur...

So to summarize things, by adopting the approaches above, CII gives us the option to choose either method in evaluating flange leakage in a piping system. My confusion also stems from how CII categorizes their flange checks and their flange leakage/stress calculations. Why don't they include all the approaches under the same classification i.e "Flange Leakage Calcs or something similiar" and allow us users to select whichever method we want to employ? Then again, perhaps they just wanted make life easier for us users and included the flange checks in the piping spreadsheet data.

This is just me thinking aloud or there may be other reasons to doing so or my whole understanding on the flange leakage - flange evaluation is incorrect. I am not criticizing CII and its usage as I am an ardent supporter of its software. I just want to get my facts straight and learn from the more learned.

Thank you for your thoughts and opinions. It will be much appreciated.

Cheers

Caesar is a tool and as many say it is probably the best available. But it will not replace you. It is your decision what method to use and is fair this way.

Regards,

Hi,

For guidance i want to tell my style while evaluating flange leakage.

During input i select the flange check option and evaluate flanges according to Equivalent Pressure method. If i see something critical or bizarre during equivalent pressure method i do Asme check which is too much detailed and exact , i guess so.

Use equivalent for simple analysis
Use Asme check for all critical lines.


Regards

Hi,
Asme VIII Div 1 or 2?