  We obtain hydrodynamic descriptions of a broad class of conserved-mass
transport processes on a ring. These processes are governed by chipping,
diffusion and coalescence of masses, where microscopic probability weights in
their nonequilibrium steady states, having nontrivial correlations, are not
known. In these processes, we analytically calculate two transport
coefficients, the bulk-diffusion coefficient and the conductivity. We,
remarkably, find that the two transport coefficients obey an equilibriumlike
Einstein relation, although the microscopic dynamics does not satisfy detailed
balance condition. Using macroscopic fluctuation theory, we also show that
probability of density fluctuations obtained from the hydrodynamic description
is in complete agreement with the same derived earlier in [Phys. Rev. E 93,
062135 (2016)] using an additivity property.
