Hello,

i´m evaluating a Y-Piece with following dimensions

Header NPS20"(wall thickness 4mm)
Branch 12" (wall thickness 3mm)
tilt angle 45°
Pressure 4,0 barg

In my CaesarII calculation with Sif from the ASME B31.3 as unreinforced Tee, there are no Problems !
Maximum Ratio of 50% from allowable Stress (incl. SUS/EXP Loadcases).

Due to PED regulations i did some alternative calculation (only inner pressure) according AD-2000 and also with Nozzle Pro.
In this Evaluation the Y-Piece Fails (mare than 400% Ratio from allowable)

I recalculated with CaesarII and the SIF´s from Nozzle Pro for Header and Branch. --> no Stress exceedance !!!

From Nozzle Pro there is a Pressure SIF, this SIF box in Caesar II is inactive!?!?

Why is this box deactivated ?
Is there a possibility to activate this pressure SIF box in Caesar II?
With this pressure SIF there should be a realistic Evaluation of the Y-Piece ?!?! is this correct ?

Or is there something i missed in my mind.

(Ver.:8.00.00.5600 Build 150930)


Hope somebody can help me !
Thanks in Advance !

Wolfgang

At the moment the Piping Codes are silent on the proper use of a pressure SIF/Index. Initial work with PRG indicates this value can be very high, so at this time the axial SIF/Index is used.

Thank you for your quick response !

Please correct me if i understand this wrong:

ASME B31.3 Code compliant Evaluation is without pressure SIF!
(even though Axial SIF (3) <<< Pressure SIF (29))

So there is no realistic evaluation in Caesar II possible ?
(Pressure SIF box deactivated)
Caesar II is evaluating this Branch with tilt angle 45° "better" than a Tee.

Due to European regulations i will go ahead with the Nozzle Pro calculation and increase the wall thickness. For Future Projects i will have an eye on this Topic.

CAESAR II does what the Piping Codes say. At this moment the Codes do not address a separate pressure SIF/Index.

With regards to SIFs, CAESAR II does not address laterals. A warning is issued and the user is responsible for the proper SIF value.

(You should check out FEATools, specifically the FEA option. This software from PRG does address laterals.)

Wolfgang,

I always prefer to provide the loads at the three ends of Y-piece to vendor and asks vendor to evaluate the stresses and design the Y-piece accordingly.

This is a safer mode to handle Y-piece when we have so many vagaries.

Be cautious to enter correct thicknesses for Y-piece for evaluating loads at its three ends.