Why need mechanical seal hole?

Why need mechanical seal hole? 2020 - 8 - 27 of mechanical seals generally require some processing operations, galvanized is part of the processing operation, through the way of galvanized in seal on the appearance of a layer of zinc coating, can protect the seals. So why need to on the seal process hole? 1, because of the hot galvanizing technology. Because the liquid zinc galvanizing pot temperature about 435 ℃, the seal mechanical seal on hot dip galvanized, spatter zinc liquid due to heat expansion easy blowout, produce risk. So the zinc galvanized parts are to be kept current and vent hole. 2, because of the buoyancy of zinc is bigger, can not be immersed in a hot dipped zinc plated pool. 3, mechanical seal with a heat seal explosive plating. 4, hot dip galvanized temperature is very high, there are air, if you don't punch is likely to be Fried.