its just re-ranged to 0:1 and will be expanded back out when it's sampled by the shader - exactly the same as a normal map just divide the resultant [-1:1] vector by 2 and add 0.5
You could have a texture that always matches to the next pipe (say on map channel 0) then have a blended texture for the between area on map channel 1 where you could vary the tiling.