It cracks when it gets dry. All bolts must have a head on one end and a nut on the other. All piping must be installed with valves. Gate valves have a gate inside. Glove valves have a glove inside.
Check valves have a check inside.
Angle valves have an angle inside. Plug valves have a plug inside. Diaphragm valves have a diaphragm inside. All completed piping lines must go somewhere and connect to something. The fitter is required to verify this before turnover.