What type of gas piping requires removal of permanent construction to access in a finished building?

The correct choice is concealed piping, which refers to gas piping that is hidden behind walls, under floors, or within other structural components of a building. When gas piping is installed in this manner, it is not readily accessible for inspection, maintenance, or repairs without the need to remove sections of the building's permanent construction. This can involve opening walls, tearing down ceilings, or lifting floors to gain access to the hidden piping.

In contrast, visible piping refers to piping that is easily seen and accessed. This type of piping typically runs along walls or in areas where it can be observed. Exposed piping is similar and is also located in areas where it can be accessed without any construction interference. Flexible piping, while it may be easier to work with in terms of installation, does not inherently dictate accessibility but can also be exposed or concealed depending on the installation method.

Understanding the differences between concealed and visible or exposed piping is crucial in maintaining safe gas systems, ensuring compliance with safety codes, and facilitating efficient repairs when necessary.