The force spectrum approach to the water hammer problem does not include consideration of the time relationship between modal or directional maximums. Conservative results can be guaranteed by taking the absolute summation of both the modal and directional response properties. Running one load case for each main piping run and a final load case, including all of the individual load cases, can typically provide a good indication for where problems exist.
In this example, the main piping run between nodes 45 and 75 added the major contribution to the system dynamic responses. The combination load case, which included the 45-75 and 90-110 contributions together, yielded little extra information.