How to check 45 degree branch connection in Caesar II? There's no SIF for such connections in ASME!

Hi Mav,

Caesar dont work beyond the code as my undrstanding. And even the code does not take responsibility other than 90deg as stated in the code. Therefore It is your resposibility as a designer to seek for the exact value of SIF.

Regards!

search on this forum for SIF or FEA

Basically it time to get help....

erm, (AFAIAA)

Most (UK) companies apply a "45deg" co-efficient to the sif calcs in the ASME codes for 45% intersections.

Ive seen this Co-efficient as either 1.4 or 2

Mr X is of the opinion that is actually more like <1 due to the increased area of intersection (more flexible)and is soon to be incorporated into the code.

Mr Y has suggested that it depends on the cycles due to the decrease of the nose radius at the pipe intersection.

My Stress buddy here has experiance of doing these in FEA and those results suggest a k of 1.4

Personally, i only see these on relief systems which are non cyclic (the majority of the time) and thus i am constantly tempted to use a k of 1.

So, lots of different answers.

If your company can afford it, use FEA.

Else like me, find your own solution.

The only code reference I have seen is in the french Codeti. The sif is similar to B31.3 App.D, but includes a factor {sin (a)^3/2} in the denominator, where 'a' is the lateral angle.

Just for reference, the 1.41 factor is the ratio of the outplane SIFs from Bonney Forge:

SIFo (BF laterolet)/ SIFo (weldolet)

MoverZ,

what is exact French Codeti code name and where could I buy It?
a factor for i0 and ii ?
so we have:
io'=io/sin (a)^3/2
ii'=ii/sin (a)^3/2
right?

Superpiper,
Is these coefficients for inplane or outplane SIF?
io'=io*1.4
ii'=ii*1.4

Is it right?

---------------------------------

1/sin(45)^(2/3)=1.68 ~ 1.4

hmmm....
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FEM analysis couldn't give us peak stress!

Is that would be right if we calculate SIF from FEA analysis like this:

i=K*C/2

K - SIF from FEA analysis (Ansys, Nastran e.t.c.)
C - coeficient we choose from this equation:

C=2*i90/K90

i90 - SIF for 90 degree branch tee from ASME B31

K90 - SIF from FEA analysis for 90 degree branch tee from ASME B31

Is it right?

Mav,

"What is exact French Codeti code name and where could I buy It?"

Codeti is the French piping code. Google it for more info.

Your equations are correct when compared to ASME B31.3 App.D:

io'=io/sin (a)^3/2
ii'=ii/sin (a)^3/2

Many current studies of SIF's are done by a combination of experiment and FEA analysis. See, for example, WRC 448, which discusses comparisons of test data, Bijlaard's work, and FEA.

Remind that the right sif not all is.
Your flexibility factor is also a problem.

MoverZ,
Thank you for information!
One more question:
does these factors apply only for unreinforced fabricated tee or we can apply them to reinforced fabricated tee with pad too?

Ohliger,
I think we can apply flexibility factor as for 90 degree tees = 1

MoverZ,
Are you sure these equations right?
io'=io/sin (a)^3/2
ii'=ii/sin (a)^3/2

Maybe
io'=io/sin (a)^3/2
ii'=io'*0.75+0.25
?

I've choose CODETI code for SIF and stress calculation and change branch angle to 45 degree. But in SIF scratchpad "review intersection SIF's" CAESAR still calculate SIF for 90 degree intersection!! And there's no such parameter as "intersection degree"
Caesar doesn't calculate SIF for 45 degree connections per CODETI code?

Well actually CODETI was updated to align with EN-13480. With that revision, the 45 deg lateral is no longer addressed.

Found SIF for 45 degree lateral branch in Piping Handbook:
i=0.9/h^(2/3), h=1.97*t/r

I think the right equation for CODETI is
io'=io*sin(a)^(3/2)

(I haven't seen codeti code yet)

For 45 degree lateral branch we have
codeti: io'=io*sin(45)^(3/2)=io*0.59
piping handbook: io'=io/1.97^(2/3)=io*0.64

I have performed FEM analysis for lateral branch 0-45 degree and I think these equations are right for bending stress SIF.
But FEM shows that SIF for torsion moment is very high for 45 degree connections...

I've used NozzlePro, Ansys and own FEM software. I use coefficient for peak stress 1.35 for primary local membrane and bending stress as recomended by Paulin rerearch due to fatigue experements

Mr.Richard,

What about "BF laterolet" In SIF spread sheet?
If possible pl reply with the exact SIF Calc for 45 deg laterolet and lateral TEE

Regards,

raja