Queries related to ASME B16.5 Flanges

[mitulmech]

Dear Group Members,

1.I am not able to find suitable material in ASME B16.5 for UNS 41000 (13%Cr).

Is this material not listed under B16.5? What are the alternative material can be used?
Or
We need to go for design nozzle flanges?

2. API 6A flange for 10000# Rating
We are designing equipment with ASME Sec.VIII Div.2 with 450 bar design pressure which pressure rating is exceeding 2500#.
Piping engineers are using API 6A flanges for attached piping to equipment.

Can we use this flanges without performing any additional calculation as STD. Flange for pressure vessel designed as per ASME Sec.VIII Div.2?
Please note API 6A is not listed under acceptable standard in ASME Sec.VIII Div.2.
Or
We need to go for design nozzle flanges?

Please share your views.

 

[SnTMan]

mitulmech, 1, true, no 410 material listed.

2, not familar w/ Div 2, but I'd say you are going to have design your own flanges that will mate w/ the API flanges.

Regards,

Mike

 

[ricklts]

Mitulmech,

Too often, 6A flanges are used as an easy out, but one thing most people tend to forget is that the title of the spec is for "Wellhead and Christmas Trees". Transition flanges traditionally attach to the production piping immediately downstream of the choke/flow restriction device. As an attachment to a pressure vessel (heater/treater/pig launcher) you might wish to analyze the API designed flange but use materials agreeable to Div. 2. Otherwise, you will be in the uncharted 'unlisted materials' category, as with the 410.

Have you thought of using one of the proprietary compact flange/hub connections for this application?

Rick

 

[mitulmech]

Thanks for reply SnTman and ricklts.

In both case we are as of now doing "design flange" to suit dimension as per standard flange to match with piping.
However as expected no. of bolts are exceeding. If required to solve this we may need to give piping counter flange along with equipment nozzle flange than piping need to be butt welded.

I thought for API 6A there may be some way (interpretation or hidden clause) to use it as STD. Flange.
Just for info for API 6A the material is SA 350 LF2 Cl.1 which is listed material but API 6A is not listed as acceptable STD. in Div.2.
I forgot to clarify in original question that both question refers to different equipment.

Other members can add their views.

Static Equipment Engineer

 

[Gilmiril]

Regarding the API flange being used for 450bar, are the piping engineers using a 5000psi flange uprated to 6650psi? That happens fairly regularly (and we've done it), but note that doing so makes it non-API-monogrammable. Part of the rationale for this is that the test pessure, at 1.5x rated pressure, would be about 10 000 psi, which is what older versions of API 6A required for a 5000psi rating (API 6A used to require 2x rated pressure but now only requires 1.5x)

But even with this, I wouldn't think that SA-350 LF2 CL1 would be acceptable material. For an API-monogrammable 5000psi flange, at least 45K material is required, and I'm pretty sure LF2 only qualifies as 36K. If we were doing this, we'd insist on meeting all API requirements except for uprating the flange, and we'd insist that the client take responsibility for the design.

Don't know if this helps at all.

 

[sharmass]

For both the cases design your flanges using appropriate Code rules