Liquid Slurry Service----care to be taken

I have used both Pinch valves and kife gate valves in slurry service. The knife gates tend to work better with large pneumatic actuators for piping where rock or stone is involved. I have seen demos of knife gates close on a 4" rock and seat properly.
Lap joint flanges can be used to rotate the pipe 1/4 turns for even wear and i have used chrome carbide lining in the pipe for extra durability.
Even with that the pipe still wears out and has to be replaced which is removed per flanged spool.
In Oil Sands mines the bitumen is so thick and viscous that check valves are not required on the centrifigal pumps discharge piping as the back flow is so slow that the velocity doesn't reach enough speed to damage the pump.

I would like to add another items:
- We are using Knife Gate Valves.
- We consider to install flanges at elbows that can be useful for the operators to solve any blockage on pipes.
- Erosion and abrasion effects must carefully consider on pipe thickness.
- The vlaves must be minimized, the valves are possible Slurry settling points.

Regards