[wnrf piper]

Depending on the slurry but we had to put plenty of drains in, generally put them in larger than you would for liquid service.
You do this because if the pump fails or something else halts the flow in the line, you need to be able to fully drain all the line rapidly before the solids settle out and block the line. Aslo plenty of flanges for 2 reasons if the latter happens and to aid in replacement of worn sections.I should add I wouldnt worry about socket welds, the materials you mentioned cross contamination wouldnt be an issue. unlikely that you will have fittings 2″ down on slurry lines anyway.