The use of a sealing layer of a composition including at least one polyamide for preparing a multicore structure intended for the transport, distribution or storage of hydrogen, in particular for the distribution or storage of hydrogen, especially for the storage of hydrogen, the sealing layer satisfying a test for contaminants present in the hydrogen and extracted from the sealing layer after contact of the hydrogen with same, the test been carried out as defined in the standard CSA/ANSI CHMC 2: 19, the total proportion of said contaminants extracted in the hydrogen being less than or equal to 3% by weight, in particular less than 2% by weight of the sum of the constituents of the composition.