seam-strap

from The Century Dictionary.

• noun In iron ship-building, a long narrow strip of plate uniting two plates at a flush joint in the direction of their length. A double seam-strap is composed of two strips, one on each surface of the plates, the joint being between them. A seam-strap is further distinguished according to the number of lines of rivets on each side parallel to the joint, as a single-riveted or a double-riveted seam-strap.