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.
Seal springs push the faces back together, causing chipping. This damage can happen on either the inside or outside diameter. The seal faces in Photo 7 have been pitted. Strain occurs from thermal expansion and is released by cracks. Material is wiped away by face contact.