Any experiances with these?

http://www.ebay.co.uk/itm/3-Piece-Me...W-/14078865170

Wondering if they would be able to expand a tube enough to fit in another, same size, tube. (in this case 2.5"x1.5 304)

Just want to expand the edges to make them slide into eachother enough to stay together and be welded around.