Thanks Dave,

Please check my summary of understanding from this discussion.

In summary:

For pseduo static and response specturm method for surge force analysis::

1. I will apply force on the face of suddenly stop valve (Axially only)
2. I will apply force on all upstream elbows in two directions (Axial and orthogonal)seperately in vector 1 and vector 2 (NOT AT A TIME)

Please correct me if my understanding is not right

Thanks for your help.