The Melting point that is quoted on safety data sheets is always the "normal" melting point of a solid. That is, the melting point when the ambient pressure is 1 atmosphere ( 1 bar). The melting point of a solid is usually slightly pressure-dependent; this dependence is described by the Clapeyron equation. However the pressure dependence is weak, and the melting point of most solids changes by at most a few degrees Centigrade for pressure increases of hundreds or thousands of atmospheres.