A105 Pressure Temperature Rating - ASME B16.5 and ASME BPVC VIII Div 1 3

[MechanicalEng2015]

The 2019 BPVC VIII Div 1 changed the classification of as-forged A105 flanges from Curve B UCS-66 to Curve A UCS-66 to address brittle fracture possibility.

ASME B16.5 still rates an A105 flange to -20F.

Why has B16.5 not followed BPVC UCS-66?

 

[akpipelineengr]

B16.5 doesn't purport to address brittle fracture in any detail. That is specifically left to the User to apply the requirements of the applicable design code per para. 2.5.3:

"Some codes or regulations may require impact testing for applications even where temperatures are higher than −29°C (−20°F). When such requirements apply, it is the responsibility of the user to ensure these requirements are communicated to the manufacturer prior to the time of purchase."

 

[MechanicalEng2015]

Thank you @akpipelineenr. Great response.

Somewhat related to my original post, do you know why A106 Grade B piping was not moved to Curve A of UCS-66? I read that carbon steel piping was also experiencing brittle fracture phenomena in addition to A105 flanges.

 

[TGS4]

The phenomenon was more pronounced in the forgings as compared to pipe. But there were extensive discussions at Subgroup-Toughness of Section VIII on this issue. In the end, it was committee decision.

 

[MechanicalEng2015]

Thank you all.

 

[akpipelineengr]

Some good summaries of the issue:

[URL unfurl="true"]https://becht.com/becht-blog/entry/reduced-toughness-properties-of-some-modern-carbon-steels-create-brittle-fracture-risk/[/url]

[URL unfurl="true"]https://www.thefabricator.com/tubepipejournal/article/metalsmaterials/best-practices-to-prevent-brittle-fracture-in-carbon-steel-pipe-flanges-fittings[/url]