one of my alloys has been repaired previously with a 25-30mm crack on the inside rim but it seems to be slowly leaking air.
someones told me if its been welded once it cant be welded again. is this true? or can I send it somewhere to be repaired properly?

 

I can't see why it can't be welded again. Grind it out til clean then do it properly

 

Drill a small hole at the end of the crack so it won't continue then fill it up with weld

 

Ive spoken to another wheel repairer this morning , he said if there's extra metal on top of the original repair its been mig welded, thoeyll grind that away and drill the hole at the end of the crack and tig weld it and itll be fine.

 

See if you can get them to do this on both sides of the surface area where the crack is. Hub facing and tyre facing. Less chance you'll need a future repair...

 

Never heard of mig welding alloy before?

 

Yeh things like tipper lorry bodies are miged.

 

Very common, just depends where you look.

For mass produced items in industry TIG would be far too costly and slow, unless it really was very critical items.

The main issue with it is getting the soft wire up the torch, so often a spool gun is needed instead of a regular torch.