How nasty does the sealing ring get?

The true deterioration of sealing rings under extreme operating conditions.

1. Contaminant penetration and solidification

Oil sludge armoring: In mining machinery, dust, metal debris, and thickened grease adsorb on the surface of seals. High temperature and high pressure form a hard crust (up to 5mm thick) that completely loses its elasticity, requiring a chisel to remove.
Metal particle embedding: Sealing rings on steel rolling lines are repeatedly impacted by iron oxide scale (Fe₃O₄), embedding hard particles into the rubber matrix. During operation, they continuously scrape the shaft journal like sandpaper, forming deep spiral grooves.

2. Irreversible damage from chemical corrosion

Swelling and erosion: Nitrile rubber rings in fuel systems expand by over 30% in volume after contact with biodiesel, squeezing out of the groove like sludge and eventually being sheared and torn by moving parts.
Acid erosion and powdering: Chemical pump seals are corroded by sulfuric acid mist, forming green copper salt crystals on the surface (ZnO in the rubber reacts with the acid). The matrix becomes brittle and disintegrates into powder with a pinch of the finger.

3. Mechanical Structural Damage

Lip Burst: Under a pressure shock of 40 MPa, the U-shaped seal ring lip of a construction machinery hydraulic cylinder explodes longitudinally along the fiber reinforcement layer, causing fragments to mix with the oil and clog the servo valve.
Abrasive Cutting: Silica sand infiltrates the seal ring of a cement kiln rotary joint. The hard particles plow a V-shaped through-groove in the seal surface, causing fluid leakage to occur in a jet-like manner.

4. Extreme Manifestations of Thermal Damage

Carbon Layer: Diesel engine exhaust manifold seals are subjected to prolonged exposure to 300°C. The rubber decomposes and fuses with carbon deposits, forming a black ceramic-like crust with visible honeycomb-like pores in the cross-section.
Pyrolysis and Pulverization: Overheating of the brake chamber seal causes the molecular chains to break, resulting in charred particles during disassembly, emitting a pungent odor.

5. Signs of Biological Attack

Bacterial Cavities: Sulfur bacteria breed in the seal rings of sewage treatment plants. Their metabolites corrode the rubber, forming sulfide pores (1-2 mm in diameter), resembling insect-eaten wood in cross-section. Rodent tooth marks: The sealing ring of the transformer in the wild is gnawed by rodents, leaving tooth marks deep into the core bone. Grease seeps along the tooth marks and attracts more creatures to gnaw on it.