Inflatable body, and method and device for manufacturing same

A method for manufacturing an inflatable body (1020), such as an airbag, comprises the steps of: providing a first longitudinal fibre web (61) comprising a first substrate layer (63) with a first set of fibres (62); providing a second longitudinal fibre web (71) comprising a second substrate layer (73) with a second set of fibres (72); cutting web segments (75) from the second longitudinal fibre web; positioning the web segments onto the said first longitudinal fibre web at an angle; performing a heat treatment, so that at least the substrate layers of the two webs melt together, in order to thus form a crossply (1000; 2000); placing two sheets of crossply onto each other; locally performing a heat treatment on the two sheets so that the carrier layers locally melt together, wherein the melting spots together form a curved sealing line (1010) defining an inner space (1013) between both sheets.