Sect VIII Div 1 2019 B16.5 A105 Flanges

[Oylwel]

Does the new 2019 update of ASME Sect VIII Div 1 limit the MDMT of as forged B16.5 A105 flanges without impact testing to 0F (and not down to -20F) or does the restriction only apply to the nozzle section of long welding neck flanges? Thank you.

 

[Trestala]

It should apply to A105 in general whether used as flange, nozzle neck, etc. Also lowest temperature is 18F for Curve A as applicable to A105 in as-forged condition.

 

[marty007]

It applies to all B16.5 flanges - See paragraph UCS-66(c).

 

[Oylwel]

Thank you for responding to my earlier question. Upon further digging, I read that UG-20 gives you exception and allows you to use A105 flanges, purchased as forged, down to -20F without impact testing if the thickness (as defined in Fig UCS-66.2)is below 1/2". That is to say if an ordinary A105 weld neck flange is welded to an A105 nozzle and the nozzle thickness is less than 1/2", you can use both without impact testing down to -20F on the vessel. Is this a correct interpretation of UG-20? Thank you again.

 

[TGS4]

I'm not saying that this is a good interpretation of UG-20(f), but I can tell you that there are serious concerns with the low temperature toughness of A105 material. Do not try to take advantage of any possible exemptions - use it at a warmer temperature or use a different material. Anything else would be foolhardy.

 

[Don56]

What about normalized A105? Which curve does it belong on? See attached.

 

[david339933]

Can't seem to open your link...but normalized are Curve B, per Figure UCS-66 notes. Also exempt to -20F per UCS-66(c)

 

[Don56]

david339933see Figure UCS-66 Notes 2(a) and 3(b). There appears to be a conflict.

 

[david339933]

Thanks for explaining....hadn't noticed that. 2017 Edition doesn't have that statement under Curve B, only under Curve C.

 

[r6155]

We must work with the latest edition.
In 2019 edit See LIST OF CHANGES IN RECORD NUMBER ORDER
18-2303 Revised UCS-66(c) and Figure UCS-66 to address low toughness concerns with SA-105.

Regards

 

[david339933]

Still doesn't explain the conflict/discrepancy with Fig. UCS-66 note 3(b). 3(b) should have been revised as well to not state "all materials".