RCC-M Subsection C and D - CAESAR II - Help

CAESAR II Users Guide

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CAESAR II
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CAESAR II Version
13

Calculate pressure stiffening using RCC-M Subsection C and D

Pressure stiffening is not defined by default in the code. You can enable pressure stiffening on bends in the analysis by including the Use Pressure Stiffening option in the configuration file.

Flanged end modifications using RCC-M

Modifications resulting from flanged ends are permitted providing the bend is not a widely spaced miter.

Calculate stress intensification factors (SIFs) for intersections using RCC-M

Inplane and outplane SIFs for intersections are the same for these piping codes.

Calculate SIF for branch connection using RCC-M

If you do not want to use the SIF for branch connections, found in Figure C3680.1 of the code for welding and reinforced reduced tees, include the No Reduced SIF For RFT and WLT option in the configuration file.

Calculate the RCC-M allowable stress limits

Use the equations below to calculate the stress allowables.

Expansion Allowable

=

F (1.25Sc + 0.25Sh)+(Sh - SSL)

Sustained Allowable

=

Sh

Occasional Allowable

=

OCC * Sh
OCC defaults to 1.2 for Level B
OCC defaults to 1.8 for Level C
OCC defaults to 2.4 for Level D

Where:

F = Cyclic Reduction Factor

Sc = Cold Allowable

Sh = Hot Allowable

SSL = Sustained Stress (PD/4t + 0.75i Mb/Z)

OCC = Occasional Factor from the CAESAR II configuration file

Calculate Pvar using RCC-M

Pvar represents the difference between the operating pressure and Pmax, which is used in eq 10. To satisfy equations 7 or 8 use iMc/Z stress as the maximum of either F(1.25Sc + 0.25Sh) or F(1.25Sc + 0.25Sh) + (Sh - Ssl) where Ssl is the sustained stress as defined by equation 6.

Calculate reducers using RCC-M

For reducers RCC-M states that the flexibility factor is 1.0. The code also states that the SIF is:

The minimum of 2.0 or 0.5 + .01*alpha* SQRT(D2/t2)

Where:

D2 = Diameter of the Small End

t2 = Thickness of the Small End

Alpha is the reducer cone angle in degrees.

If not specified:

Alpha = atan[ 0.5 * (D1-D2) / (0.60 * length of the reducer element) ]

Alpha cannot exceed 60° and the larger of D1/t1 and D2/t2 cannot exceed 100.