There are 6 types of Waterproof Pipes: Wooden, Cobblestone, Stone, Iron, Gold and Redstone. Waterproof pipes are made from normal pipes by adding Pipe Waterproof. Waterproof pipes can transport Water, Lava, Oil, and Fuel.
Pipe placement is important. If you want to remove items from a furnace (all furnaces work for this), for example, then a wooden pipe needs to be attached to one of the sides of the furnace. A pipe connected to the top of a furnace places items into the top spot, and a pipe connected to the bottom of a furnace puts items into the bottom spot. If this is glitchy, wait for the power (any source) to, in a way, heat up
If you connect pipes in a loop, the world/server will not deteriorate.