Patent ID: 7690549

Claim:
A purge arrangement for welding backup of a seam between two surfaces selected for welding together along respective runs which define said seam; said purge arrangement comprising: a porous sheath; a ventilated tubeform inserted inside said porous sheath, said tubeform being provided with an axially-distributed plurality of vents and adapted for flooding with a purge gas by a source thereof in order to flood the interior of the porous sheath therewith in turn; adhesive tape attached for forming a seal across the back of said seam and sealing in said porous sheath as well as the ventilated tubeform inside thereof along the back of said seam whereby said porous sheath when flooded with the purge gas flushes the interspace between said tape and seam and ultimately flushes the as-yet un-welded portions of said seam with said purge gas.