Regarding Comparisons of WRC 107 and WRC 297
Assumptions in each document as I understand them are listed below, and may
provide some help in use:
WRC 107 Cylinder-to-Cylinder Intersections (Cyl-to-Sphere is different)
- Nozzle Connection is assumed to be a rectangular loading surface (no
nozzle, no hole) for circ and longitudinal moment loads.
- Axial load stresses are derived from point load on a cylinder
extrapolated to outside edge of nozzle. (Again, no nozzle or hole is assumed
in the WRC approach. This assumption is illustrated by the fact that the
nozzle thickness does not have an effect on the 107 cyl-to-cyl stresses as
long as the OD of the nozzle does not change.)
- No attempt is made to include fillets, radii or repads. The fact that
many WRC 107 programs include these characteristics are due to further
extensions and assumptions provided by the software developer.
- WRC 107 has no provision for pressure loads. The adding of pressure to
external loads has historically been problematic for WRC 107 calculations.
- WRC 107 does not provide flexibilities of the intersections.
- Torsion and shear load stresses are computed as M/2I and F/A
respectively. There are no attempts to account for the opening of the nozzle
and attachment to another cylindrical shell.
- Stresses in lateral connections were not considered in the original WRC
107 document, but results due to moment loads tend to be reasonable.
- It is often thought that 107 should not be used above d/D ratios of 0.5,
although experience indicates that effectiveness in common sizes is
surprisingly good up to much larger d/D ratios. (0.9 or so within the
assumptions discussed above.)
- Not intended for small D/T ratios.
WRC 297 (Cyl-to-Cyl Only)
- Attempted to correct some assumptions in 107.
- Correlated with limited and small d/D FEA runs.
- Transverse midplane slope of nozzle and shell at penetration assumed
equal.
- Includes effect of nozzle, nozzle opening and nozzle thickness.
- Does not include pressure effects. (See WRC 468)
- Includes stiffness calculations in Fig 59&60 that can easily be used to
produce numbers that are off by several orders of magnitude (high and low)
since extrapolation on log-log plot is required for geometric parameters.
- May produce excessively conservative stresses in the nozzle, (200%) (when
compared to FEA results), and so has seen limited use.
- Vessel-side stresses for certain loads and parameter ratios agree very
well with WRC 107.
- Not intended for small D/T ratios.
We recommend comparing stress results from WRC107/297 due to the individual
(usually the highest) load to the stress results from FEA exposed to the
same highest individual loads. (Multiple loads makes separating the
differences in the approaches very difficult.)
Inside and outside shell/plate FEA surface stress intensities at the plate
penetration line should be compared directly to the stress intensities
computed in the WRC documents L and U/inside and outside locations on the
circumferential and longitudinal planes only.
Other provisions should be made in the cases where highest stresses occur at
45 degrees from circ or longitudinal planes (See WRC 107 B1 and B2 location
stresses.)
Hope this helps.
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Subject: [PipingDesign] Differeence between WRC 107 & WRC 297
Hi all,
1.Could you please give an idea about WRC 107 & WRC 297(difference).
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Received on Sat Aug 27 21:30:00 2005