Corrosion rate measurements are made using the LPR technique. The instrument measures the current required to polarise the electrodes of a probe to a known potential. From the polarisation potential and the measured current, polarisation resistance can be calculated. Then, using Faraday’s law, instantaneous corrosion rate is calculated from polarisation resistance. The PZD Linear Polarization Resistance probe offers the advantage of fast response to changes in corrosive conditions that exist in the system being monitored. This rapid response allows the operator to evaluate the process changes and inhibition program, and make necessary adjustments. LPR probe body is manufactured by 316 stainless steel with an AISI 1018 mild steel element. Probe body and element are available in alternative materials upon request. Standard probes are designed for mounting through a Hollow Plug assembly. This allows the probe retrives without process shutdown, using a retriever tool and service valve .