Metallic pipe joints shall be permitted to be ____________ using proper pipe and fittings.

In the context of metallic pipe joints, the option that involves "Welded or Brazed" is particularly significant because these methods create strong, permanent connections that are essential for maintaining the integrity of pressure systems, such as those that handle propane.

Welding involves melting the base metal and adding filler material to form a joint that becomes one with the two pieces of pipe, which makes it ideal for high-pressure applications where gas containment is critical. Brazing, on the other hand, uses a filler metal that has a lower melting point than the base materials, allowing for connections that still provide strength while being less demanding in terms of heat application.

These methods are crucial for ensuring that joints can withstand the mechanical forces and thermal expansions that might occur in a piping system affected by propane. They are typically preferred in applications where flexibility, leakage prevention, and the ability to manage pressure fluctuations are prioritized.

In contrast, other options such as clamping and flanging provide less robust solutions that may not be suitable for high-pressure environments due to their potential for leakage under stress. Meanwhile, screwing may be functional but generally does not offer the same level of strength and stability required for safe propane distribution systems.