| 摘要 |
A duct comprising a tubular body of glass fibers and a surrounding jacket formed of laminated sheet material of which the inner layer comprises a substantially vapor impervious heat sealable thermoplastic resin and of which the outer layer is formed of sheet material, contributing strength to the joint and which is also substantially vapor impervious, the opposite edges of the sheet laminate being brought together around the tubular body and having the thermoplastic resin layers of said opposite edges heat sealed together. A method for applying the jacket is also disclosed, comprising heat sealing edge portions of the jacket together to form a slack loop larger than the perimeter of the duct body, assembling the loop and duct body and thereafter tightening the slack loop on the body by a further heat sealing operation.
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