but in this case i can't neglect the SIF value

since it is a Big bore pipe (16") with less wall thickness and if we are taking a branch of 3" using weldolet the SIF value is so high
eventhough i did't model the branch pipe simply i break the node and use weldolet connection SIF
in that case it self it is failing

for heavy thick pipes there is no problem only for the thin wall pipes are failing

in such cases how to solve this issues