Inflatable tubular structure with spiral seam

An inflatable evacuation device comprising:

• at least first and second inflatable tubular members;
• the first inflatable tubular member being spaced from the second inflatable tubular member, a floor extending between the first and second inflatable tubular members and being constructed of a flexible material;
• each of the first and second inflatable tubular members being constructed of an elongate flexible strip of woven fabric, the elongate strip having a first elongate edge and a second elongate edge extending substantially parallel to the first elongate edge, the elongate flexible strip of woven fabric includes a first set of threads extending in a warp direction and a second set of threads extending in a fill direction substantially transverse to the warp direction, a bias direction of the woven fabric extends at an angle to the warp and fill directions;
• and
• the elongate strip being spiraled into a tubular shape such that the first elongate edge is adjacent the second elongate edge to thereby form a spiral seam extending along a longitudinal axis of the respective tubular member;
• wherein in each of the first and second tubular members the warp direction is substantially parallel to the spiral seam, and to enhance expansion the bias direction extends along a circumference of each tubular member.