just had some alloy pipes tig welded but they have a white oxide on them, whats the best thing to use? wire brush?

If it's the white bit alongside the weld it's the cleaned area where the arc has done its job, don't worry about it. You can polish it if you really want to though.

a white pan scrubber does a nice job if it's a brushed finish.

green ones also work, but they're a bit coarser and don't quite match the brushed finish as well

tom