Fire caused by oxygen replacement

The main process of the accident
A mechanic welder at a pesticide factory was welding a baffle in a breeding pot with a diameter of one meter and a height of two meters. There was no exhaust equipment inside the equipment, so the welder used oxygen to blow away the smoke in the pot.
However, when the welder entered the pot again to weld, there was a "bang" and a fire broke out. The welder's burn area exceeded 80%, and third-degree burns accounted for 60%. He died after 7 days of rescue.

The main reasons for the accident
(1) Using oxygen as a ventilation source is a serious violation of regulations;
(2) No ventilation device was set up when entering the container for welding.
How to prevent accidents?
(1) Ventilation devices should be set up when entering the container for welding; (2) The ventilation gas source should be compressed air.