The Double Compression Plate is based on the Compression Plate Seal. The assembly of the seal could be from the top of the tank roof. The seal can be installed while the tank is in service as it doesn't need to be welded. The seal can be adapted to the tank deformations since this is custom made. The draw shows a skirt designed to be introduced in the stored product to reduce product losses. The vapour barrier membranes are normally manufactured from polyurethane-coated nylon fabric with very low vapour permeability properties. PVC Nitrile, PTFE/Teflon or Fireclose materials may be adopted depending of customers' requirements.