Multilayer structure for transporting or storing hydrogen

A multilayer structure intended for transporting, distributing, or storing hydrogen, comprising, from the inside to the outside, at least one sealing layer and at least one composite reinforcement layer,

• said innermost composite reinforcement layer being wound around said outermost adjacent sealing layer,
• said sealing layers consisting of a composition comprising:
• more than 50% by weight relative to the total weight of the composition of at least one long-chain polyamide thermoplastic polymer P1i, i=1 to n, n being the number of sealing layers, semi-crystalline including the Tm, as measured according to ISO 11357-3:2013, is greater than 160° C.,
• said long-chain polyamide thermoplastic polymer having an average number of carbon atoms per nitrogen atom greater than 9,
• excluding a polyether block amide (PEBA),
• up to 50% by weight of impact modifier relative to the total weight of the composition,
• up to 1.5% by weight of plasticizer relative to the total weight of the composition,
• said composition being devoid of nucleating agent,
• said at least one predominant polyamide thermoplastic polymer in each sealing layer that may be the same or different,
• and at least one of said composite reinforcement layers consisting of a fibrous material in the form of continuous fibers, which is impregnated with a composition comprising more than 50% by weight, relative to the total weight of the composition, of at least one polymer P2j, j=1 to m, m being the number of reinforcement layers, said structure being devoid of a polyamide polymer layer, said polyamide polymer layer being the outermost and adjacent to the outermost layer of composite reinforcement.