Abstract: A tubular structure is disclosed. The tubular structure has an elongate pre-fabricated tube having a longitudinal axis, a machine direction and a first width, and a first sheet metal having a leading edge, a machine direction and a second width. The leading edge of the first sheet metal is bonded to an outer surface of the elongate pre-fabricated tube and is continuously and convolutely wound about the longitudinal axis forming a plurality of at least three convolutions coaxially disposed about the outer surface of the pre-fabricated tube. The first sheet metal has a tail portion. The tail portion of the first sheet metal is disposed upon and bonded to an immediately subjacent convolution of the first sheet metal along the width.

Abstract: A helically wound tubular structure is disclosed. The tubular structure has a first sheet metal helically wound about a longitudinal axis, a second sheet metal having voids disposed therein helically wound about the longitudinal axis and coaxially about the first sheet metal, and a third sheet metal helically wound about the longitudinal axis and coaxially about the first sheet metal and the second sheet metal.

Abstract: A tubular structure is disclosed. The tubular structure has a first sheet metal having a machine direction. The first sheet metal is convolutely wound about a longitudinal axis and has a tail portion. The tail portion of the first sheet metal is disposed upon and bonded to an immediately subjacent convolution of the first sheet metal.

Abstract: An elongate tubular structure is disclosed. The elongate tubular structure has a first and second tubular structure wherein a first end of the first tubular structure is matingly and fasteningly engaged to a first end of the second tubular structure. The first and second tubular structures each have a first sheet metal having a machine direction being convolutely wound about a first longitudinal axis. The first sheet metal has a tail portion that is disposed upon and bonded to an immediately subjacent convolution of the first sheet metal to form the respective first and second tubular structures.