Thanks for all your help guys.

We have tried asking the operators about the existing line. They tell us it gets a bit of waterhammer, which they say is when they suddenly run the pump backwards (maybe to try to unclog the pump or something?). However we cannot get anyone to quantify the magnitude of the water hammer. Sometimes they said the mining hose shakes a bit, but that could also be due to slug flow type issues associated with the slurry.

There are no valves in the system.

I figured that I should use the force calculated in the mining hose, and not in the steel pipe, since the pump is in the mining hose. So thanks for confirming that suspicion. We can't find any pump starting or stopping time data, so I've made an educated conservative guess. The force is quite small, and not much of an issue.