discrepancy between fig ucs-66 and fig ucs66.1

[taba94]

hi engineers
i have found a dicrepancy in ucs-66 and i would be so grateful if u clear this gray area for me.
due to the fig ucs-66 if the thickness increase the mdmt temp decrease and it makes sense cos if the thk. of the plate increase the toughness decrease.
but due to fig ucs-66.1 if your thk. increase the ratio falls and you could reduce more temp from your mdmt.
the question is why increasing the thk. is harmful for fig ucs-66(which make sense) but is useful for fig ucs-66.1?

thanks

 

[metengr]

due to the fig ucs-66 if the thickness increase the mdmt temp decrease and it makes sense cos if the thk. of the plate increase the toughness decrease.

This is incorrect for Figure UCS-66. As the thickness increases, the MDMT exemption for impact testing also increases because of reduced notch toughness from increasing plane strain conditions with thicker pressure parts.

In Figure UCS-66.1, here the discussion is about reducing the MDMT and exemption for impact testing by evaluating the thickness ratio or the coincident stress ratio to take advantage of a lower membrane stress, and lower risk of brittle fracture.

 

[SnTMan]

taba94, review UCS-66(b). Fig UCS-66.1 is not based on thickness, as such, but on excess thickness. It provides a means to decrease the MDMT based on, you might say, reduced stress.

Regards,

Mike

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