MDMT of FVC Forged Nozzles

[xema77]

I have a vessel with an MDMT of -10ºF and the requirement of integrally reinforced nozzles. The nozzles being provided are a variety of forged nozzles (LWN, HB, F and V series).
UCS 66(c)(4) provides criteria for exemption of LWN's if the MDMT is no colder than -20ºF. Is there any exemption criteria for HB, F and V series forged nozzles? How is the MDMT determined for these forgings?

 

[LSThill]

Request the Materical Cert. for the FV Nozzle

 

[TomBarsh]

Assuming this is ASME Code (as per your ref to UCS)...

UCS-66(c)(4) provides exemption only for the "flange" portion of the long weld neck, not the weld attachment to the shell. Even for LWN you still have to investigate the MDMT rating for the weld to the shell (after all, why should this be any different than a nozzle constructed of a weld neck flange and, say, a forged neck equivalent to the neck of the LWN?).

Same thing for the other forgings: HB, F, V, etc. These and the LWN (and any other nozzle construction) have to be investigated using the rules of UCS-66 (for carbon steel, or equivalent paragraphs for other materials).

Be aware of Code Interpretation VIII-01-1-37. This stipulates that when the shell is the governing thickness at the nozzle-shell weld then "tr and tn are those of the shell." This can make a HUGE difference in MDMT ratings for nozzles with heavy barrels relative to the shell thickness.

For "how the MDMT is determined"...see the examples in Appendix L-9.

 

[xema77]

Tom, thanks for information. How are the "flange" portions of HB, F, V handled? For example, if the governing thickness of the nozzle neck and shell meets MDMT requirements do we assume that the "flange" portion of these other forgings is also covered by UCS-66(c)(4)?
UCS-66(c)(4) indicates that the neck ID shall not be less than the nominal size of the flange. The ID of HB and V nozzles are slightly smaller than the nominal flange size. Therefore it appears that all of these forgings would require impact testing. Is this the case?

 

[TomBarsh]

The "flange" is addressed by UCS-66(c). Standard flanges can be rated to colder temperatures by the use of UCS-66(b)(1)(b).