Copper Alloy Resistance to Liquid Mercury

Virtually all copper and copper - nickel alloys (brasses, bronze alloys, monel) are potentially susceptible to mercury LME. Under conditions where liquid mercury is present, the degree of susceptibility depends in part on alloy metallurgy but other factors such as stress, strain, cold work and plastic deformation can dominate when considering probability of failure. The circumstantial risk factors for mercury- caused failure of copper alloys are poorly-studied but likely similar to those required for aluminum. In particular, mercury must be present in liquid state, stress must be present and mercury must contact the copper alloy via some breach in the surface oxide. A major difference in copper LME susceptibility as compared with aluminum, is that the oxide on copper alloys is less protective than the oxide on aluminum. The oxide on copper alloys is thinner than the oxide on aluminum and therefore easier to fracture or abrade.

The uncertainty in assessing risk of copper alloy LME failure also stems from a lack of statistical data on circumstantial risk factors such as the necessary amounts of liquid mercury and stress. Copper alloys are less likely to be used in high pressure applications and therefore are less likely to be exposed to liquid mercury in gas processing systems where liquid mercury might be present. For this reason, statistics and circumstantial correlations on copper alloy failures due to mercury are not readily available.