Trunnion Stress Checkl Calcuation

Dear All,

As per my knowledge we are checking the stresses at Trunnion and Run pipe junction based on the Kellogs formulae.
It is
S=(1.17*(R^0.5)(F1+1.5F2)/(t^1.5)
where F1= Unit loading due to longitudinl Bending moment(M/∏R^2)
F2= Unit loading due to radial thrust(W/2∏R)

Please tell me that is there any change in the values of F1 and F2 when trunnion is attached for an elbow.

what u r saying ,please explain in detail.

Dear Madhu,

I am having two types of documents for Trunnion Clacluations.

In 1st document, when trunnion is attached for Straight pipe,
F1= Ml/(∏ R^2)
F2= F/(2*1.3*∏*R)
and when trunnion is given at veretical Elbow,
F1= Ml/(1.7*∏*R^2)
F2= F/(2*∏*R)

where as in 2nd document
F1= Ml/(∏ R^2)
F2= F/(2*∏*R)

F1 and F2 values are same when the trunnion is attached for Straight pipe and vertical elbow.

Explain which one is best suitable and why we have a factor in 1st document.

It is not clear what you are asking, perhaps you can post the documents that you are talking about.

Dear Mr.Richard Ay,

As per ASME Code case N-392-3, we are calculating the attachment stresses at the trunnion connection point.

In the code it is specified that the attachment stresses shall be added to the code stress to check for the acceptance of the trunnion support.

My query is how i can input the attachment stress i.e. additonal stresses at the trunnion point in the Caesar-II model to check for the overall stress.

Please clarify...

You can't. This check is something you will have to do manually, outside of c2.

Dear Richard Ay,

In caesar Trunnion support SIF option is available, may i know which C value i need to use from ASME Code case N-392-3...

I can't make that kind of recommendation.