If the polished surface is damaged beyond this limit, the seal will drip. A series of drips will form a stream. Shaft rotation causes the stream to cover the driver with a spray until operations or maintenance covers the equipment with some sort of deflecting shroud. Typical observations of damaged mechanical seal faces and their causes are indicated in Photos 1-7. The product then evaporates between the faces, causing poor lubrication.
Crystals form between the faces, further damaging seal face flatness by causing scratches.
Photo 4 shows heat checking, which results from poor lubrication that causes localized expansion, which is relieved by cracks. Photo 5 illustrates the effect of erosion, which occurs when abrasive particles penetrate the spaces between the seal faces. Chipping is shown in Photo 6 . This occurs when product evaporates between the seal faces. Evaporation causes expansion and the seal faces separate.