Meaning
Physical breakdown of long-chain polymer molecules occurring when materials are subjected to mechanical stress at extremely low temperatures results in permanent changes to material performance. Cryogenic shear degradation happens during the processing or transport of liquefied gases where moving parts apply force to brittle substances. The reduction in molecular weight alters the viscosity and mechanical strength of the material.
Molecular Instability
Polymers lose their flexibility as the temperature drops below the glass transition point. In this state, cryogenic shear degradation breaks covalent bonds rather than allowing the chains to slide past each other. The resulting fragments change the physical properties of the fluid or solid.
System Reliability
Engineers must account for these changes when designing pumps and valves for sub-zero environments to prevent catastrophic loss of containment. If the material breaks down, the seals might fail or the lubrication properties might disappear entirely. Regular testing ensures that the selected polymers maintain their integrity under the specific flow rates and pressure cycles required for the continuous operation of the plant.
Performance Penalty
Loss of structural integrity leads to increased maintenance costs and potential system failure. When a polymer degrades, the change in flow characteristics often forces the operator to reduce pump speeds. Sustained operation at these lower levels impacts the overall throughput of the facility.
