hello

is it possible to model the flanges directly with the line, how to check if the flanges with ceasar ii?


regards

Yes, you model them as rigid elements - or use the valve/flange database and select "flange-pair".

At the flange locations, you check check the checkbox for "Flange checks", which lets you performe either a "Peq B16.5" check or an "NC3658" check.

Hi Richard,

Should not it be like "Peq" or "NC3658 B16.5" instead of what you mentioned?

Check the documentation on "Flange Rating" in the Technical Reference Manual. You'll find that the Equivalent Pressure (Peq) must be less than the "pressure rating". That value of "pressure rating" comes from B16.5.

The NC method is based on the "Sy" value of the flange material.

Sir Richard,

In basis calculation of stress analysis:

Maximum operating pressure of fluid + Peq < Pressure Rating.

Why Caesar doesn't sum both Pmax & Peq before compared to Pressure Rating? Or Do I miss something?

Richard,

By 16.5, I meant the NC method is only valid for B16.5 flanges.
(<24")

Sam:

The equation for the "Peq" method is:

Peq = 16M/(pi)G3 + 4F/(pi)G2 + PD &#8804; Pressure Rating

"PD" is the pressure of the specific load case.

Jozm:

I don't recall NC stating that limit, but I don't have the Code with me.

Richard,

just as an idea,
Caesar can automatically reject when we are going to leak analysis an e.g. 30"- flange by NC.

Dear Richard,
Below is the output of calc. Caesar II ver. 5.20. I don't know it in version 5.30

Node (9670)
Axial Force (48 N)
Bending Moment (14 N.m)
G/C (76.38 mm)
==>Peq (1.74 bar)

Rating Temp. (25.50 deg C)
==>Allowable Pressure (102.04 bar)

==> ratio (1.71%) = Peq/Allowable Pressure = 1.74/ 102.04

I think ratio shall be:
==> ratio = [max ope. pressure + 1.74 bar]/ 102.04

I think Caesar needs to consider which pressure (P1, P2,..) as max pressure in the menu like selecting (Tamb, T1, T2,..) for flange Allowable Pressure.