Below find a list of inspection drones that matches up with circumstances in whatever way you want to plan your inspection.
Flyabilitys Elios 3, for internal inspections such as pressure vessels, boilers etc
DJI Matrice 300, for external inspections such as stack exteriors, cell towers etc.
DJI Phantom 4 Pro, for roof inspections
Yuneecs H520, for inspecting cell towers.
It has become utmost important for every industry to carry out visual inspection, and hence the drones are being extensively used. Using drones instead of humans not only gets you accurate datas, but also saves lives by not being present in dangerous situations.