When will FEA be Required in a Submission?

File: NA
Last Updated:
LB

Finite Element Analysis (FEA) is required in a submission when code equations cannot be directly applied to the configuration and/or when additional reinforcement needs to be accounted for to obtain acceptable stress values.

B31.3 Code pipe or shell calculations assume a thin uniform cross section. These calculations do not accurately predict the resultant stresses in this scenario.

When code adaptation calculations are performed for the following 24" butterfly valve, a shell-equivalent area is used to calculate the hoop stress.

Solid model
The equivalent area fulfills t<D/6 Req’t (304.1.2(a)).
Drawing of valve
Even though it satisfies the t<D/6 requirement, this equivalent area approach was rejected by the reviewer. FEA is the only alternative.
Solid model showing 1/4 model
Due to symmetry, the entire valve can be analyzed by the quarter model shown in the figure.
Stress Linearization results
A stress linearization was performed on two sections of the body resulting in membrane stresses of 1,129 and 789 PSI, and membrane + bending stresses of 1,449 and 1,034 PSI.
Maximum stress
The maximum stress corresponds to a peak stress, as per Fig. 4-130.1 ASME VIII-2. A fatigue analysis yields infinite life cycle to ASME VIII-2 Fig. 5-110.1.1.
UltraFlo valve
The stresses and corresponding cycle life were acceptable and Ultraflo obtained a CRN#.

A special thanks to Ultraflo Corporation, #8 Trautman Ind. Dr. Ste. Genevieve, MO for allowing use of their valve geometry for this exercise.