Which type of fitting is NOT allowed in concealed locations?

In the context of propane installations, plastic fittings are not permitted in concealed locations due to safety concerns. Concealed areas, where fittings are hidden from view, can pose a significant risk if a leak occurs. Plastic is generally considered less durable and more susceptible to degradation from environmental factors, such as UV light and temperature fluctuations, compared to metal fittings. Therefore, using plastic fittings in hidden spaces increases the risk of undetected leaks, which can lead to hazardous situations.

In contrast, threaded elbows, tees, and brazed fittings are typically constructed from materials such as steel or copper, which are more robust and reliable for use in concealed applications. These materials can better withstand conditions that may be encountered in concealed installations, contributing to overall system safety and integrity.