Detection of corrosion rates in processing pipes and vessels

A method for determining a corrosion-related value for a sensor in a fluid flow in a corrosive or erosive environment, comprising:

• providing at least one mechanical oscillator and locating the at least one mechanical oscillator in the fluid flow, wherein the at least one mechanical oscillator including one of (i) a mechanical oscillator having two regions of differing corrosion resistance, wherein one of the two regions is a reference region that is resistant to corrosion in the fluid flow and another of the two regions is a non-resistant region that is not resistant to corrosion in the fluid flow, or (ii) a first mechanical oscillator having one corrosion resistance that is not resistant to corrosion in the fluid flow and a second reference mechanical oscillator having a different corrosion resistance that is resistant to corrosion in the fluid flow;
• exciting the at least one mechanical oscillator disposed in the fluid flow;
• monitoring the at least one mechanical oscillator to obtain a plurality of sampling values at a plurality of times from the non-resistant region or the first mechanical oscillator, a sampling value comprising at least one of a resonant frequency f and a quality factor Q, wherein the monitoring further includes obtaining a plurality of reference sampling values at the plurality of times from the reference region, or the second reference mechanical oscillator;
• forming pattern window vectors having a first window size based on the plurality of sampling values, each pattern window vector being associated with a time from the plurality of times;
• determining residue values for the pattern window vectors at the plurality of times based on a mean vector and a variance, the mean vector and the variance for a pattern window vector associated with a time being based on at least a portion of the pattern window vectors;
• identifying one or more residue values greater than a threshold value;
• excluding sampling values from the plurality of sampling values that correspond to times associated with the one or more identified residue values, wherein excluding sampling values further includes excluding reference sampling values from the plurality of reference sampling values that correspond to times associated with the one or more identified residue values;
• and
• determining a corrosion-related value based on sampling values from the plurality of sampling values that are different from the excluded sampling values and reference sampling values from the plurality of reference sampling values that are different from the excluded reference sampling values, wherein determining the corrosion-related value based on the sampling values and the reference sampling values comprises determining the corrosion-related value based on a ratio of the sampling values and the reference sampling values.