In the current version of CAESAR II (2016 - Version 8), if all densities are zero (pipe, fluid, insulation, etc.), then water weight (WW) will be zero. When CAESAR II "buries" your pipe, these densities are all set to zero. If you bury you pipe on your own, check these densities.
You may also see some response to WW (from the above ground (non-zeroed) pipe) at the transition if your buried line continues above ground.
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Dave Diehl