{HEAD ~ The welding seam} can have {TAIL ~ any desired shape}, as long as it exhibits a sufficient length and strength, in order to ensure a permanent joining of the sheets 
{ HEAD ~ The welding seam } can have { TAIL ~ any desired shape } , as long as it exhibits a sufficient length and strength , in order to ensure a permanent joining of the sheets
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH