Tubular protective sleeve having a knitted dual layer wall and method of construction thereof
A thermal protection tubular sleeve includes a knitted inner wall having circumferentially continuous outer and inner surfaces. The circumferentially continuous inner surface bounds a cavity that extends lengthwise along a longitudinal central axis between opposite inner ends of the knitted inner wall. The tubular sleeve further includes a knitted outer wall having circumferentially continuous outer and inner surfaces. The knitted outer wall extends lengthwise about the longitudinal central axis between opposite outer ends and overlies the knitted inner wall. An intermediate yarn extends back and forth between and through knitted loops of the outer wall and knitted loops of the inner wall to connect the knitted outer wall and the knitted inner wall to one another.
1. A tubular sleeve for providing thermal protection about an elongate member, comprising:
a knitted inner wall having a circumferentially continuous outer surface and a circumferentially continuous inner surface, the circumferentially continuous inner surface bounding a cavity extending lengthwise along a longitudinal central axis between opposite inner ends of the knitted inner wall;
a knitted outer wall having a circumferentially continuous outer surface and a circumferentially continuous inner surface, the knitted outer wall extending lengthwise about the longitudinal central axis between opposite outer ends, the knitted outer wall overlying the knitted inner wall; and
an intermediate yarn extending back and forth between the knitted outer wall and the knitted inner wall to connect the knitted outer wall and the knitted inner wall to one another with the circumferentially continuous outer surface of the inner wall engaging the circumferentially continuous inner surface of the outer wall.
2. The tubular sleeve of claim 1 , wherein the knitted inner wall is knitted entirely with a first yarn forming interlinked inner knitted stitches and the knitted outer wall is knitted entirely with a second yarn forming interlinked outer knitted stitches, the inner knitted stitches not knitted to the outer knitted stitches.
3. The tubular sleeve of claim 2 , wherein the intermediate yarn is the sole connection of the knitted inner wall to the knitted outer wall.
4. The tubular sleeve of claim 3 , wherein the intermediate yarn is knitted with a tuck stitch.
5. The tubular sleeve of claim 4 , wherein the inner knitted stitches and the outer knitted stitches are formed using weft knitted stitches.
6. The tubular sleeve of claim 5 , wherein the weft knitted stitches are jersey stitches.
7. The tubular sleeve of claim 2 , wherein the first yarn and the second yarn are multifilaments.
8. The tubular sleeve of claim 7 , wherein the first yarn and the second yarn are different types of material.
9. The tubular sleeve of claim 7 , wherein the multifilaments consist of at least one of, fiberglass, ceramic, basalt, silica, slate, slag, aramid and carbon.
10. The tubular sleeve of claim 7 , wherein the intermediate yarn is a monofilament.
11. The tubular sleeve of claim 10 , wherein the monofilament is heat-set to impart a bias on the knitted inner wall and the knitted outer wall to maintain a predetermined shape.
12. The tubular sleeve of claim 1 , wherein the opposite inner ends are radially aligned with the opposite outer ends in substantially flush relation.