Mommy,Daddy Where do Flange Ratings come from ?& why you should check them out ?

Does this remind you of WWE ?

What is this 150 Pound , 300 pound flange ? Is this the weight of the flange like those WWE players ?? 

Well this rating come from a far more exciting place called ASME B16.5(if pipe size is less than 24 inches ) /ASME B16.47(if pipe size is greater than 24 inches)

Don’t run away seeing this names of standards its far simple !!!

Every material has a certain limit of pressure and temperature it can withstand so we have the PT tables in this standard which describe at a particular rating say 300# how much pressure and temperature it can with stand !!

Example

For 300 Class (Also referred as Rating) Flange

The material Carbon Steel (mentioned in snap as “ A105 “ a commonly used grade of carbon steel ) can withstand 37.6 Bar of pressure at 350 Deg C .

Here’s the Catch !!!!

For same 300 Class of flange

The material stainless Steel (mentioned in snap as “ SS316L “ a commonly used grade of stainless steel ) can withstand 25.1 Bar of pressure at 350 Deg C .

Do you see the difference ?

For same class 300 flange at 350 Deg C , SS316L can only withstand 25.1 Bar while CS A105 can withstand 37.6 Bar !!!!!

But if you compare the corrosion resistance YES ! SS316L is more corrosion resistant than CS A105 as it has very low carbon content .

In one of my projects Hydrocracker unit which had High Pressure &Temperature majority of SS flanges did not fit in the PT rating hence higher Flange rating had to be used and the same had to be informed to piping that even they have to do the same !!(So that both flanges are of same dimensions )

So be safe, keep you plant/Project Safe and also your JOB safe :p and always check PT ratings in ASME B16.5/16.47 !!!

PS: This is as per best of my understanding , I still have a lot to learn !!!!

I hope this article was helpful even if in a small manner !!