Expansion loops are NOT made with which of the following types of fittings?

Expansion loops are designed to accommodate the thermal expansion of piping systems and are typically constructed using specific types of fittings that can effectively allow for movement and flexibility. The types of fittings used in expansion loops include butt weld, socket weld, and bell end fittings, as these provide strong and secure connections while also allowing the necessary movement for the purpose of the expansion loop.

Threaded fittings, on the other hand, do not offer the same structural integrity for an expansion loop application. While they can be used in various plumbing and piping applications, they are not ideal for expansion loops due to the potential for leaks and the inability to accommodate the thermal movements associated with expansion and contraction. The use of threaded connections in high-stress areas, especially where significant movement is expected, can lead to failures over time, making them unsuitable for this specific purpose.