Method of forming pipe liner 100 comprising fabric sleeve 1 with barrier coated inner surface 120 and longitudinal seam 106 includes providing sheet of fabric with barrier coating, bringing opposing edges 103, 104 together to form sleeve with barrier coating on inner side, providing strip of carrier material 130 comprising a liquid sealant on one surface inside the sleeve and on the opposing edges of fabric joining together the opposing edges with the carrier strip. The sealant may be a molten polymer. The carrier, barrier material and molten polymer may comprise the same polymeric material. Pressure may be applied to the carrier strip, liquid sealant and opposing edges. A coolant liquid may be applied to the liquid sealant on the inner surface of the sleeve. The coolant liquid may comprise a dye. The method may include flattening the pipe liner for storage or transportation. The method may include passing the liner through a quenching station with entry, low and exit points, where the coolant fills a section of the liner passing through the low point. Also claimed are a method of testing a longitudinal seam of a pipe liner during manufacture and apparatus for forming pipe liners.
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