Disclosed is a method of monitoring a condition of objects in a piping system in which each object has a surface exposed to a product flowing through a pipe in the piping system. The method allows for the condition of each object to be monitored whilst the object remains in place. The method includes repeatedly measuring a resonance frequency of an oscillatory element of a vibratory device that is installed in the pipe and that exhibits a susceptibility to an impairment caused by accretion, abrasion, and/or corrosion corresponding to the respective susceptibilities of the objects. The resonance frequency of the vibratory device is reduced by accretion and increased by corrosion and by abrasion of its oscillatory element. The method further includes monitoring the condition of the objects based on the measured frequencies.