How can you connect natural gas fittings to a propane tank?

To connect natural gas fittings to a propane tank, you need to ensure compatibility by using a propane-to-natural gas conversion kit, which includes the appropriate regulators and fittings. First, turn off the propane supply and ensure all components are rated for the pressures involved. Then, carefully follow the kit instructions to replace the propane regulator with the natural gas regulator, ensuring all connections are secure and leak-free. It's crucial to consult a professional or local codes to ensure safety and compliance.