Large cylinder roller jack for valve positioning - GIF

[Jon]

Large cylinder roller jack for valve positioning.




Previously:

Spinning/rolling gas cylinders to transport them - video
Gas cylinder welding fire - GIF

[Toolmaker51]

?! Because they snore while sleeping on their sides?

[NortonDommi]

How much vino is in those cans?

[desbromilow]

you may find it's to stop internal components "brinelling" by sitting in one orientation too long. When we store electric motors, or things with bearings we have a schedule where we rotate the shafts every quarter so the bearings won't "settle" and cause divots in the races. Generators and other similar rotating machines have the same issues with material creep causing small deformities under gravity, and then when the unit is brought into service, those small deformities cause premature wear and failure of the bearings, etc.
Those units look like large accumulators, which will have internal components such as metallic bladders, and perhaps some oils. by rotating them periodically it may be preventing localised corrosion to the interior of the shell caused by condensation, etc, or sag in the bladder. A reliability engineer or technician will know more than I about that.