Swedish Method 1 and 2 - CAESAR II - Help

CAESAR II Users Guide (2019 Service Pack 1)

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CAESAR II Version
11.0 (2019)

Calculate pressure stiffening using Swedish Method 1 and 2

Pressure stiffening is not defined by default in the code. You can include pressure stiffening on bends in the analysis by including the parameter Use Pressure Stiffening in the setup file.

Flanged end modifications using Swedish Method 1 and 2

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

WRC329 recommendations

Swedish Method 1 cannot take advantage of the WRC 329 recommendations. WRC 329, if requested, is ignored.

Calculate effective section modulus using Swedish Method 1

Swedish Method 1 has no provision for using an effective section modulus calculation at intersections.

Calculate stress intensification factors (SIFs) for intersections using Swedish codes

Inplane and outplane SIFs for intersections are the same.

Swedish Code item 9 is dealt with as a US tapered transition. Also, items 10 and 11 in the Swedish table 9:2 correspond to items 8 and 9 in the CAESAR II nomenclature.

Calculate the allowable stress limits using Method 1

Use the equations below to calculate the stress allowables.

Sber = lesser of Sh or F

Allowable = (Fac)(Sber) / 1.5

Where:

Sh = Yield Stress at Temperature

F = Creep Rupture Stress at Temperature

Fac = Usually 1.5 for Pre-stressed Pipe Use 1.35.

Calculate the allowable stress limits using Method 2

Expansion Allowable = f ( 1.17S1 + 0.17S2 )

Sustained Allowable = Sh

Occasional Allowable = Occ * Sh

Where:

f = Cyclic Reduction Factor

S1 = Lesser of Sc or 0.267Sy

S2 = Lesser of Sh or 0.367Sy

Sc = Allowable Stress at Room Temperature (Stn2)

Sh = Allowable Stress at Design Temperature (Stn1)

Sy = Ultimate Tensile Strength at Room Temperature

Occ = Occasional Load Factor Default is 1.2

Default girth butt welds for Swedish Method codes

If the weld is ground flush inside and out then the default SIF value for a girth butt weld is 1.0.

Pressure Variation in Swedish Codes

Swedish methods 1 and 2 Beta in the code is entered in the Pvar field on the Allowable Stress Auxiliary dialog box. Enter the value for Pvar in percent, for example 10.0 for ten percent. If left blank, the default is 10.0 percent.

Limits on the reasonable Betas that you may enter for the Swedish piping code is 10% to 25%. Anything less than 0.1 is taken to be 10% and anything entered greater than 0.25 is taken to be 25%.

Pressure Stress in Swedish Codes

Include the Use PD/4t option in the setup file to tell CAESAR II to use the thin walled equations for stress calculations for Swedish Method 1 code compliance.

Default occasional load factor for Swedish Method 2

The default value for the occasional load factor for Swedish Method 2 is 1.2.

Pad thickness using the Swedish Method 1 and 2

The pad thickness on an intersection reduces stresses up to pad thickness of 2.5 times the header wall thickness.

Calculate reducers using the Swedish Method 1 and 2

The default value for the flexibility factor is 1.0 and the equation to calculate reducer SIFs is:

2.0 max or 0.5 + .01*alpha* SQRT(D2/t2)

Where D1 and t1 are the diameter and thickness of the large end and D2 and t2 are the diameter and thickness of the small end.

Alpha is the reducer cone angle in degrees.

Where:

Alpha = atan[ (D1-D2) / (2*length of the sloped portion of the reducer*0.6) ]

SHARED Tip Alpha is the slope of the (concentric) reducer transition in degrees. If unspecified, CAESAR II calculates alpha using 60 percent of the entered reducer length.

Other Swedish Notes

If you are using Swedish Method 1 to calculate the CAESAR II allowable, assume that the SIGMA(tn) multiplier is 1.5 for piping that is not pre-stressed. If you use pre-stressed or cold sprung pipe change Fac on the Allowable Stress Auxiliary field to 1.35 as per the Swedish code.

Use the corroded section modulus for all stress calculations as per the definition of Di in the Swedish code.