How should underground ducts be protected if they are metallic?

How should underground ducts be protected if they are metallic?

• A. They must be painted
• B. They must not be used
• C. They must be insulated
• D. They must be encased in concrete

Answer: (D)

Metallic underground ducts are susceptible to corrosion and damage from moisture and soil conditions. Encasing these ducts in concrete is an effective method of protection, as it creates a barrier that shields them from environmental factors that could lead to degradation. This method also provides structural support and minimizes the risk of physical damage arising from soil shifting or external pressures. While painting metallic ducts may offer some level of corrosion resistance, it is often insufficient without the additional protective measures that encasement provides. Simply insulating the ducts may not adequately prevent moisture exposure if not properly sealed. Additionally, the option of not using metallic ducts altogether does not address the issue of installation and usage, provided that the correct protective measures are taken.

Metallic underground ducts are susceptible to corrosion and damage from moisture and soil conditions. Encasing these ducts in concrete is an effective method of protection, as it creates a barrier that shields them from environmental factors that could lead to degradation. This method also provides structural support and minimizes the risk of physical damage arising from soil shifting or external pressures.

While painting metallic ducts may offer some level of corrosion resistance, it is often insufficient without the additional protective measures that encasement provides. Simply insulating the ducts may not adequately prevent moisture exposure if not properly sealed. Additionally, the option of not using metallic ducts altogether does not address the issue of installation and usage, provided that the correct protective measures are taken.