Is it okay to place concrete in metal pan stairs by letting it flow from the top landing all the way to the bottom (20 steps) filling each step as it flows down
The concrete will likely segregate leaving all the coarse aggregate in the top couple of stair pans, while the rest are nothing but cement/sand paste. Concrete must be placed. That's why the contractor is not supposed to dump concrete into a wall form and "drag" it into position with the vibrator.
they walked in the fresh concrete, used gradall bucked to load from truck then lifted to 2nd floor transferred to wheel barrow then dumped down the stairs
It's a steel stair, so the concrete is just a wearing surface, but it is unacceptable practice. If they are this sloppy in their work, I would be suspicious of everything they do.
As Hokie points out, strength is not an issue on this. The concrete is just a wearing surface for the stairs. Durability over time will be the true test.