Sanitary Manhole Cover(pressure manhole, sight glass) Export to USA, UK., tank manufacturer since 1996. ISO9001- ... 2008 APPROVED! Sanitary Manhole Cover(pressure manhole, sight glass)Dimensions: 250*100mm -600*120mmThickness: neck 5mm, cover 4mmPressure: ... ): round, elliptical and square. They are widely used for the equipment(tanks, vessels) of food, beverage, beer, pharmacy and dairy ...