Color contamination problems as the carbon wears. Slurries clog up the sliding seal components and open the faces. Cryogenic fluids can attack some carbon faces and most elastomers. High temperature fluids attack elastomers and change the state of the fluid you are sealing. Some fluids can cause the formation of ice outboard the seal, restricting seal movement as the face wears.
Agitation can cause some fluids to change their viscosity.
Cleaners or solvents are attacking a seal component. Pumping the supply tank dry, causing excessive vibration and heat. Series or parallel pump operation can cause shaft deflection. Running at a critical speed will cause the shaft to defect. Low N.P.S.H. Air getting into the system through packing.