API Flange for pipe size less than 2"

[Redpipe]

Can you help me please? I am very confused about API flange.

Now I have piping specification for API 5000 class from two big companys in offshore field.

Both said that flange 3/4"-2" will be class 5000 RTJ as per API 6A Type 6B and gasket will be API 6A Type "RX"

However, when I checked API standard, There are no flange size less than 2.1/16" shown in API 5000. I can find only 1.13/16" (1.5") flange on API 10000, 15000, 20000 and also gasket will be type "BX" only.

So, I am thinking that both piping spec. for two company may be not cleared. If I order flange 1.5" API 5000, vendor may supply flange 1.13/16" API 10000 and gasket type "BX".

However, when I checked ASME B16.20 (1997), it shows flange 1" and 1.5" API5000 which use gasket R20 or RX20.

So, it make me more confused.

Anyone can tell me what I can believe about API flange.

Thanks you very much

 

[Zapster]

you may find the information you need using the FLANGE SLIDE RULE PROGRAM at

http://www.woodcousa.com

 

[Luiz001]

Fellows,

Take this post opportunity I'd like to ask. In my country there's a oil company that rules everything by itself, no matter what other codes like ASME, A|PI, ASTM, etc, states. My question is:

For a flowing pipe's fanges, what really counts to determinate if it'll be rtj or rf or something else, the flow passing thru or the pressure class?

Luiz

 

[Ashereng]

Typically for most applications, RF (raised face) flanges we use up to about class 900 ANSI. After class 900, we go to RTJ (ring type joint).

In steam service, it is common to see RTJ, even at low and lower pressure classes. I guess because it seals better?

I would say that the use of RTJ is more due to pressure than flow rate, at least in my industry.



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