Back to the WRC107/297 question... 2

[Heyner]

Hi everybody!

I'm designing a DSS hrizontal drum ø84"x180"LTT, and my customer ask in the specs for nozzles analysis per WRC107 and WRC297, giving me the loads per each nozzle size (P, Vc, V1, Mc, M1, Mr).

Some softwares I've found talk about the 107 but never mention the 297... I really don't know details on these calculations, can somebody tell me what's the mean purpose of each bulletin (107/297), when you need to use each of them, if I really need to use both...

Once more: I know these bulletins have been revised on 2002 and 1987, I'm not sure if softwares are updated, salesman didn't know...

Some recommended software?

I have NPS 6, 4, 3 & 2 nozzles on cilindrical shell and Semielliptical heads, using reinforcing pads.

Thanks in advance!

 

[LSThill]

Heyner (Mechanical)

Nozzle PRO BY

http://www.paulin.com/

Leonard Thill

 

[LSThill]

Heyner (Mechanical)

Nozzle PRO BY

http://www.paulin.com/

• When the d/D ratio for a loaded nozzle is greater than 0.5 and WRC 107 or
297 is considered for use.
• When the t/T ratio for a loaded nozzle is less than 1.0 and WRC 107 or 297
is considered for use.
• When the nozzle is pad reinforced and WRC 107 or 297 is considered for
use.
• When the number of full range pressure cycles is greater than 7000 and the
nozzle is subject to external loads.
• When the D/T ratio is greater than 100 and SIFs or flexibilities are needed for
a pipe stress program.
• When the D/T ratio is greater than 100 and a dynamic analysis including the
nozzle is to be performed using a piping program.
• When a large lug is used in a heavily cyclic service.
• When pad reinforced lugs, clips or other support are placed on the knuckle
radius of a dished head. WRT 107 simplifications for pad reinforced rectangular
lug attachments are fraught with potentially gross errors.
• When seismic horizontal loads on vessel clips or box supports are to be
evaluated.
• When pad reinforced hillside nozzles subject to pressure and external loads.
• When evaluating large run moments, but small branch moments in a piping
system.
• When there are overturning moments on skirts.
• When the effect of integral vs. non-integral pad on nozzle in head should be
studied.
• When there are different thermal expansion coefficients or temperatures
between the header and branch.
• When the loads on nozzles are high because of the assumption that the
nozzle connection at the vessel is a rigid anchor. Few connections at vessels
are rigid. Even small rotations can significantly reduce the calculated
moment and stress. Accurate flexibilities permit the actual moment on the
vessel nozzle to be calculated and included in design.
• When there is heat transfer in an axisymmetric model geometry.
• When the effect of adding a radius to weld geometries on nozzles in heads
should be investigated.
• When the anlayst needs to run various model types, comparing results to determine
the stability and accuracy of the solution. To verify FEA calculations,
NozzlePRO allows nozzles in heads to be analyzed with shell, axisymmetric,
or brick finite elements.
• When horizontal vessels are saddle supported, with or without wear plates,
and including tapered saddles with many design options.
• When evaluating the effects of axial or transverse loads due to internal sloshing,
wind loads, seismic loads, or general external loads. Zick’s methods
do not consider either axial or transverse loads.
• When designing pipe shoes for self-weight, liquid weight and axial loads.
When You Need to Use NozzlePRO

 

[arto]

Don't forget to check the Nozzle flange joints per Kellogg/Stikvoort - this is often the limiting case for forces & moments.

 

[StressGuy]

Arto,

If the engineering company knows what it's doing, they've already considered the flanged joint issues when generating their nozzle load tables. That issue is not going to a factor for the vessel designer.

He'll be wanting to use WRC (or Nozzle Pro/FE Pipe, which is our preference) to check the stresses at the nozzle shell interface to determine wall thickness and reinforcement requirements.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[Heyner]

Good info, boys, but...

May somebody explain to me the purpose of WRC107 and WRC297 separately?

Are they two different methods to check the same, or...

Thanks...

 

[StressGuy]

They are the "same" in the sense that they address stresses in pressure vessels at nozzles due to external loadings. WRC-107 is the original. WRC-297 is a revision/extension/supplement to WRC-107. This thread gives a good explanation:

http://www.eng-tips.com/viewthread.cfm?spid=794&newpid=794&sqid=97749

I would agree with those posters, use FEA like Nozzle Pro instead of these WRC bulletins if you have it. The bulletins are from a time when this analysis was likely to be done by hand. I actually know a few older guys who've done WRC calcs by hand. Now that's my definition of torture!

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[codeeng]

Go here and click on Notes....WRC-107 and WRC-297. This will give you an understanding of both bulletins:

http://www.pipestress.com/Pages/PEpapers.html

Generally though these are being phased out with the easy to use FEA programs like NozzlePro. Comments from Isthil re: gross errors using WRC is particularly true.

 

[LSThill]

Heyner (Mechanical) and Team Members:

Pressure Vessle Program like COMPRESS

http://www.codeware.com

have FE-NOZZLE and it take less than two minits to check the NOZZLE in the DESIGN OF THE ASME DIV 1. & DIV 2. Check for NOZZLE LOAD'S fx, fy, fz, Mx, My, Mz. Large Piping Load form the Piping Stress Engineer.

learn more

http://www.codeware.com/docs/TrainingVIII-1.pdf