WN nozzle joint efficency

[Bobfromoh]

I would like to know how the nozzle joint efficiency value affects the analysis results.
I am using COMPRESS (but could be any package). There is a 14" 150# WN nozzle, XS neck,
SA-106-B material. 19" OD x 3/8" thick pad. Shell is 48" Dia x 3/8" thick. SA-516-70 pad
and shell. Design is 50 psi at 650F.

With E=1, there is a pop-up note: Nozzle is seamless material with a circumferential joint
that doesn't meet UW-11(a). Nozzle efficiency should be 0.85.
Weather I use 1.0 or 0.85, the resulting calculations are the same as far as I can tell.
How does this joint efficiency affect the calculation?

 

[SnTMan]

It does not, it's just the software nagging at you. Calculations are typically based on circumferential stress, not longitudinal.

Regards,

Mike

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

 

[TomBarsh]

For a "usual" nozzle, UG-37 applies and therein 'trn', the required thickness of the nozzle neck, is stated to be that for a "seamless nozzle neck, using E = 1". So I would not expect the reinforcing area and related calculations to vary based on the joint efficiency.

The nozzle neck joint efficiency will come into use when determining the required nozzle neck thickness per UG-45. It will affect "ta" as found per UG-27. This value may not govern in all cases (probably rarely).

If you specify nozzle loads then COMPRESS will also check the nozzle neck for the longitudinal stresses induced by the loads+pressure. This will give you "ta" found by "UG-22", but this calculation will not use the joint efficiency for the longitudinal weld (or seamless).

And the designated joint efficiency will also get sucked up into the determination of the "RT" marking of UG-116.

If you add a flange (etc) to the end of the nozzle and specify some level of radiography for which the user input value of E for the longitudinal seam is now "correct" per UW-11/UW-12 then the nagging goes away.

-Tom Barsh - Codeware

 

[Bobfromoh]

Thanks for the replies.