Venting is often over-looked on channel frames as they are already open. When tilted on their side, the flanges of the PFC or beam create a channel that fills with zinc and air and so needs to be vented.
Trailers are turned on their edge and dipped at 45 degrees. The holes need to allow molten zinc to fill and drain from the frame and allow superheated steam and ash to escape. Bolted sections and moveable joints need to be removed to prevent them locking up.