Can we call this a ANSI B16.5 standard flange?

[D2HANDLE]

Hello everybody,

I am recently working on an Exchanger for Lube oil service.
It is a very small exchanger and is to be used for cooling of Lube oil with cooling water. Shell ID is just 141.3mm and the exchanger body flanges and shell are made up of 5" pipe / ANSI B 16.5 standard flanges.
However since the exchanger is TEMA type BEW (Externally sealed type floating head), the rear shell side flanges (5", 150#, RF)have been machined by the Vendor at gasket seating face to incorporate the gasket support ring for the floating tubesheet.Please refer the attached sketch for details.

My question is - Can we still call this a ANSI B16.5, Standard RF flange for which no design calculations are necessary?
I am not sure but I just heard from some other discussions that once a standard flange is machined in anyway, it is no longer compliant to B16.5 standard and must be calculated / designed as per ASME App.2 / other acceptable method.

Kindly share your opinion.

Thanks everybody who spent time reading and answering this post....i really appreciate the kind gesture of the experts out here...

 

[GenB]

I see no problems with the flance it just that by machining you voided the original spec for RF. You should have bought the full face flance and didn't have to machine it. GenBlr

 

[SnTMan]

D2HANDLE, B16.5 permits removal of the raised face by machining provided the basic thickness, tf, is not reduced, see para. 6.3.2.

It appears you have not removed the entire raised face, however, as long as you have not reduced the tf dimension, I'd say you are B16.5 compliant.

Some might take issue with the jackscrew and dowel hole drilling, however I personally would not.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[nickelkid]

I think the only issue that may cause calculations to be required is that the diameter location of the gasket will no longer fall within typical gaskets for B16.5 flanges. I do not expect any issues with the design.

 

[SnTMan]

nickelkid, to that I'd say, since B16.5 flanges are usable with a variety of gaskets, from narrow ring to full face, including solid metal ring gaskets, no issue there either.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[TGS4]

To be completely pedantic, you would want to call them ASME B16.5 flanges (it hasn't been an ANSI standard in a long time.

I would definitely take issue with the other holes - they would result in the flange not being compliant to ASME B16.5.

 

[SnTMan]

Told ya

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[D2HANDLE]

Thank you all for your opinions....it really helps..
I will proceed considering these flanges as standard ASME B 16.5 flanges..

 

[r6155]

How many additional holes we can do in this flange and continue with designation B16.5?
This is not B16.5 flange to me.

Happy new year!
e6155

 

[SnTMan]

Strictly speaking TGS4 and r6155 are correct, not really any longer a B16.5 flange. However this kind of thing is done on Appendix 2 flanges all the time with no accounting in the design and they work fine. Not at the top of the rating, a few small holes, no problem. Top of rating, lots of holes, well, another look is in order.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[D2HANDLE]

SnTMan,
I would double you on this one....such holes are a commonplace in almost all Heat Exchanger girth flanges designed as per Appendix 2 of Code...i never seen any "Design calculations" for all such small holes.Hope the same applies to ASME B 16.5 flanges also..

D2HANDLE

 

[SnTMan]

D2HANDLE, exactly what I was referring to. Given that your flange is a HX packing flange, temp and pressure are presumably moderate, and small size to boot. I would not be at all concerned.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[racookpe1978]

IF! the previous raised face is removed by a lathe or milling machine to assure 100% contact with the (future) gasket. A hand-cut grinding wheel field abortion (er, machining) effort will leak.