What is Full Flange Rating?

I fully agree with your statement but how can it corelates with my query about full fange rating.

Thanks

Sachin

Please, is not very clear for me what is full flange rating....The maximum value for pipe pressure....

http://www.engineeringtoolbox.com/steel-flanges-pressure-rating-d_44.html

I'm interesting in design and fabrication of piping systems in accordance with ASME code, but it is the first time to hear the term "Full Flange Rating".

May be you mean that the rating of flanges used in certain piping system have a higher rating than the rating required by the code (ASME B16.5 or ASME B16.47). In other words, may be the pipe schedule is found to be 40, where the flange rating must be 150#, but the erector uses a flanges with higher rating, may be 300#.

In ASME B 16.5, you will find material based P-T rating table in which pressure values w.r.to temperature are given .like in table no.2.1.1, max pressure that can withstand by the flange is 19 bar (for 150# this is the full rating design condition).Whereas for 150# your line design pressure will be less than this, and you calculate your pipe thickness using line design pressure. This means flanges are always designed for full rating.

Pipe thickness may be calculated based on full rating conditions.In this case PRESURE(as per 16.5 table) / MAX. ALL.STRESS (as per B 31.3 table A-1, w.r.t temp.) ratio is calculated for each pressure value. The lowest value from the ratio is the the worst design condition used for pipe thickness calculation.

I hope your doubt is clear now.

Look in ANSI B16.5 for Pound Ratings of Flanges.

These ratings are based on Pressure temperature and materials used to make the flanges

The different ASME codes, accept these ratings.

Basically in full flange rating the pipe is designed stronger than the flange, ie the pressure bearing capacity of pipe should be more than flange pressure bearing capacity.

The <...Full Flange Rating...> exceeds the pipe rating. That way, the pipe fails first on rising excess pressure.

If it were less than the pipe rating, then the flange will fail first.