What type of pipe joint is required for cross connecting fuel tanks?

The requirement for a ground joint union for cross-connecting fuel tanks stems from the need for a secure and leak-proof connection that can accommodate the thermal expansion and contraction of the materials used in fuel systems. Ground joint unions feature a design that allows for easy disassembly and reassembly, making them practical for maintenance and inspections.

Ground joint unions are typically constructed to provide a reliable seal without the risk of damaging the threads that might be found in threaded connections. This is particularly important in fuel systems, as leaks can pose significant safety hazards. The ability to maintain a tight seal while allowing for flexible movement can help ensure the longevity and safety of the fuel system.

In contrast, other joint types may not provide the same level of reliability or ease of maintenance needed in this context. Threaded joints can be less effective under vibration and stress. Welded joints, while strong, are permanent and would require cutting for any repairs, which is not practical. Compression joints may not provide the necessary durability and sealing capabilities for fuel applications, leading to potential leaks. Thus, ground joint unions are specifically favored in this application.