Dave Diehl,

Could you please clarify these doubts.

"If I was running a hammer load using a static equivalent, I would run it both positive and negative - if the system is nonlinear"

Means..

Case 1. positive and negative forces at a time, means in CAESAR-II both positive and negative forces in CAESAR-II vector - 1 only. and in next elbow both forces in CAESAR-II vector - 2 and so on ... same as Slug force application of force.

In load cases:

Check 1: F1, F2 and so on.. check individually with two forces acts on each elbow. and

check 2: F1 + F2 + F3 + .. case also considered. means at a time two forces are acting at all elbow in the entire piping system.

Case 2. Positive force in vector 1 and negative force in vector 2.

In load cases:

Check 1: F1, F2 and so on.. check individually with one force on each elbow

Check 2: F1 + F2 + F3+ .. case also considered. means at a time two individual forces are acting at all elbow in the entire piping system.

In both cases which one is correct method to safe the piping system in water hammer effect.