Large Standard Flanges

[butelja]

In vessel fabrication involving flanges between 26" and 60" diameter, class 150 or class 300, and not custom designed per appendix 2 it is common to use ANSI/ASME B16.47 flanges. My question is, are Series A (MSS SP-44) or Series B (API 605) flanges more commonly used, and why?

 

[zcdr01]

Yes, ASME B16.47 is almost always used for flanges that exceed the ASME B16.5 size range. In general, one would use Series B, which is equivalent to the old API 605 bolting dimensions. However, if you know that a flanged valve is going to be bolted directly to one of the vessel nozzles, you want to use Series A, which is based on MSS-SP-44 bolting dimensions.

If your vessel is to be installed in an existing plant facility, it is a wise practice to check the attached piping flanges to make sure you have the correct type and bolting dimensions. There could be an existing pipe with an "Appendix 2" flange, or a manufacturer's standard flange that doesn't match either Series A or B. If this is the case, you want to find that out immediately to prevent a potential embarrasing situation.

 

[gunnarhole]

Butelja,

I would like to add a few ponits to the post above.

Series A flanges are heavier than Series B flanges so if you have to buy a lot of them or if you need special metallurgy it can make a difference.

Series B flanges have more, smaller fasteners than the Series A flanges.

Series A includes corresponding dimensions for blind flange closures. Series B does not define a blind flange so you will have to design/build one if you need one.

Regards,

Gunnar

 

[seto]

Can any one tell me if "O" ring flanges are common? I specified an ansi 16.5 flange class 600 with "O" ring. Apparently no flange supplier knows what "O" rings are. Will I have to design the "O" ring and bolt stressing and put this information on a drawing? Designing a metal face-to-face flange is involved and time consuming. There must be a simpler way of specifying such a flange.

 

[prex]

Seto
there is no standard for Orings: unless you find a flange manufacturer supplying a flange pair with Oring (this may happen for example in high vacuum applications) you must specify Oring material, diameter and groove.
Concerning the calculation, if you are allowed to use B16.5 flanges, you can go on without recalculation, provided the Oring groove is not larger than the groove specified by the standard.

Why don't you start a new thread for a new topic?
prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

i thought api605 spec has already been discontinued since its been absorbed by asme b16.47. Most of our large dia RF flanges on the nozzle of the column, reboilers and reactors are to api 605 (built 1985) and we have a forge blind and figure 8.

 

WHAT IS THE MAXIMUM SIZE (OD) FOR SERIES B FLANGES, ALSO, IF YOU HAVE A CODED VESSEL AND YOUR FIRST CONNECTION TO THE VESSEL IS TO A 8" PIPE STUB, 6" LONG, PROVIDED BY THE VENDOR, IS THE FIRST WELD, YOU AS A CONTRACTOR MAKES TO THIS VESSEL, UNDER CODE OR DOES CODE STOP AT THE WELD CONNECTION PROVIDED BY THE VENDOR. IN OTHER WORDS IS MY FIRST WELD CONSIDERED A CODED WELD???

 

[butelja]

B16.47 covers sizes 26" to 60" for both series A and series B.

 

For flanged nozzles, the Code had been generally considered to be to the flange face, and thus the weld between the nozzle stub and flange was generally considered to be part of the pressure vessel and a pressure vessel Code weld. However, there has been, I believe, a recent Code interpretation that states otherwise, and permits it to be considered a piping Code weld, possibly limited to certain circumstances. I don't recall all the details. Check the recent ASME Boiler & Pressure Vessel Code interpretations.

 

I´m looking for ANSI-Welding Neck Flanges, MSS SP-44 / 600lbs; in ATSM A105N, 30":
Where can i get them ? ? ? Thanks a lot

 

[Rehmani]

I need to know the source (website link) from where I can get the information about the Ansi-Asme Standards dimensional data for Flanges

 

[xxxxxxxx]

Go to the ASME website and in there, go to publications. The dimensions are in ASME B16.5 up to 24 inch and ASME B16.47 for larger flanges.

 

[butelja]

I have found dimensional information online at the following site:

http://texmet.com/TMW.qxp3.3.pdf

. Beware, it is a large file that takes a while to download.