High rejection spiral wound elements with protective features

A method of producing a spiral wound element, comprising:

• (a) providing a center tube;
• (b) providing one or more membrane sheets, each membrane sheet being folded on itself at a fold line providing first and second membrane halves with inner surfaces facing each other, wherein each folded double membrane sheet is spirally wound around the center tube with the fold line proximal the center tube, each membrane sheet having a plurality of spacing features disposed on the inner surface of the first half;
• (c) providing a fold protection element mounted with the inner surface of the first half and with the inner surface of the second half, where the fold protection element extends from the fold a first distance on the first half and a second distance on the second half, where the second distance is greater than the first distance;
• (d) spirally winding the one or more membrane sheets about the center tube.

A spiral wound element comprising:

• (a) a center tube;
• (b) one or more membrane sheets, each membrane sheet being folded on itself at a fold line providing first and second membrane halves with inner surfaces facing each other, wherein each folded double membrane sheet is spirally wound around the center tube with the fold line proximal the center tube;
• (c) each membrane sheet having a plurality of spacing features disposed on the inner surface of the first half;
• (d) an inner wrap support element comprising a plurality of inner wrap support features disposed on the inner surface of the first half, where the inner wrap support features are disposed with a first density and the spacing features are disposed with a second density greater than the first density;
• and (e) a fold protection element mounted with the inner surface of the first half and with the inner surface of the second half, where the fold protection element extends from the fold a first distance on the first half and a second distance on the second half, where the second distance is greater than the first distance.