Orifice meter runs can be located in pipe rack if it is absolutely necessary due to space requirements. In a pipe rack, they should be located directly next to the columns so that they can be accessed with the help of a portable ladder or a mobile platform.
It is necessary to provide maintenance clearance area above orifice meter runs. Such clearance area should be marked with a box in orthographic drawing or 3D model.
It is necessary to consult the instrumentation department regarding acceptable location and orientation of orifice meter taps on orifice flanges.