Recently, our fire prevention division identified a dry barrel type fire hydrant fed by a 6" main: t-off from the incoming water service. There are multiple 90 deg angles and a piping length of approximately 250 ft. The entire hydrant feed line is installed in an underground parking garage anchored to the ceiling.
Testing of the hydrant did not work out so well. A significant water hammer occurred shearing 6 course thread 1/2 anchor bolts. The mechanical engineer's solution was to install additional supports at 90 deg elbows.
Does NFPA 24 permit this ? Has anyone in the NFPA community experienced this ?