this kind of cells the process fluids are air on the cathode side and hydrogen or hydrogen containing mixture on the anode side the depth of both compartments only crossed by gaseous phases can be modest it follows that the projections and likewise the supports have reduced heights with the above seen advantages with a single wall u2014 electrode or current distributor distance even lower than 5 mm on both sides anodic and cathodic in all the above disclosed applications of electrolysers or stacks comprising a multiplicity of bipolar plates of the invention a deterioration of the electrodes or current distributors which must therefore be replaced with new components takes place after a certain operating time in the case of the second electrode or current distributor the replacement is carried out by eliminating the securing welds to the supports for instance by grinding and by welding the new replacement piece to the freed terminal surfaces of the supports this procedure in general is to be avoided for the first electrode or current distributor since the risks of damaging the thin sheet of the projections is too high a preferable alternative procedure provides that a new electrode or current distributor thinner than the damaged one be secured by welding for instance by the cheap resistance spot welding the first damaged electrode or current distributor which is then left in place favours the homogeneous current distribution to the new thinner piece the structure of the bipolar plate of the invention and the relevant assembly procedure of the.