The question lacks some details about the design. Our response below assumes that the PVC pipe is going through the coal silo carrying drain water.
The PVC pipe may be used for this application provided that all of the following conditions are met:
• The only material that goes through the PVC pipe is water,
• The water flow through the PVC pipe is slow and does not result in the formation of droplets within the pipe,
• The mechanical integrity of the pipe is maintained and no water can leak into the coal silo,
• There are no electrically isolated conductive (metal) objects such as metal brackets or flange coupling on the outside of the PVC pipe, and
• There is no flammable vapor/gas atmosphere present in the coal silo at any time.
Generally speaking, it is suggested that an electrically grounded conductive pipe is considered instead of the proposed PVC pipe. Alternatively, consider routing the pipe from the outside of the silo.