1. A composite tape (T) comprising a first web (W1) and a second web (W2) welded together according to a welding pattern comprising a plurality of welding points (40) arranged in arrays (42', 42") extending along a first direction (MD) and spaced apart in a second direction (CD), perpendicular to said first direction (MD), with adjacent arrays (42', 42") offset from each other in said first direction (MD), and with said welding points (40) in each array (42', 42") arranged in groups spaced apart in said first direction (MD), wherein the first web (W1) has a plurality of hollow protrusions (44) alternating with welding points (40), both in said first direction (MD) and in said second direction (CD), and wherein the second web (W2) has a plurality of ribs (46) extending along said first direction (MD) and separated from each other by said arrays (42', 42") of welding points (40).