When sourcing hatch cover packings, the material composition is critical for maritime safety. You should prioritize EPDM (Ethylene Propylene Diene Monomer) for its excellent resistance to UV radiation, ozone, and weathering. For vessels carrying oil or chemical cargoes, Neoprene or Nitrile (NBR) is preferred due to its oil and chemical resistance. Ensure the packing has a solid skin with a sponge core (co-extruded) to provide the necessary compression set resistance and watertight integrity under extreme sea pressure.