... Production Line for Composite Mgo Vent-pipe Board with high efficiency, high automatic degree,low labor intensity,easy operation Production Line ... with fireproof grade A, and it can improve largely the quality of air, because it doesn’t rust, mould, accumulate ... so the product can be used by the high, middle and low pressure ventilation system. Composite Magnesium Oxide (MgO) Vent-pipe Forming Machine