CorrosionErosion PROCESS OUT OF CONTROL Corr Science Corr

Corrosion/Erosion PROCESS OUT OF CONTROL

Corr Science • Corr Science, is a Alberta based company which supplies corrioson, erosion, and MIC products for pipelines and plants

Why? Process out of control • To provide information on the interrelation between Corrsion/ Erosion/ MIC proccess and operating variables to allow more efficient use of the plant or pipline • To provide information that may be used to prevent a safety failure and or a potential disaster

Definitions • Corrosion – Chemically induced wall loss • Erosion – Mechanically induced wall loss • MMC – Biologically induced wall loss (bugs)

Corrosion Perceptions • No one Corrosion monitoring tool can solve your Corrosion problem • You will often need a combination of monitoring techniques to properly identify a problem area

Corrosion Monitoring Techniques • Electrochemical Methods • Electrical Resistance Monitoring (ER) • Linear Polarization Resistance Monitoring (LPR) • Hydrogen Monitoring • Weight Loss Coupons • Non-Destructive Testing Techniques (NDT) • Analytical Techniques

Electrochemical Methods • Electrical Resistance Monitoring (ER) • Linear Polarization Resistance Monitoring (LPR) • Galvanic Monitoring, aslo known as Zero Resistance Ammetry

Electrical Resistance Monitoring (ER) • The Action of corrosion on the elements serves to decrease the cross section area thereby increasing the Electrical Resistance • The major advantage is its ability to measure corrosion in any environment, liquid, gas or particle streams

Electrical Resistance Monitoring (ER) • The difference between ER and electrochemical techniques is that ER measurements prodie information on the totaal loss of material, which ever electrochemical techniques given rate information

Linear Polarization Resistance Monitoring (LPR) • LPR measures the corrosion current flowing between anodic and cathodic half cells • LPR monitoring provides an instanteous measure of corrosion rate and may, for example be usedas a method for optimising corrosion inhibitor injection

Galvanic Monitoring (Zero Resistance Ammetry ZRA) • ZRA probes, two electrodes of dissimilar metals are exposed to the process fluid. When immersed in solution, a natural voltage (potential) difference exits between the electrodes. The current generated due to this potential difference relates to the rate of corrosion which is occurring on the more active of the electrode couple. • • • Galvanic/Potential monitoring is applicable to the following electrode couples: Bimetallic corrosion Crevice and pitting attack Corrosion assisted cracking Corrosion by highly oxidizing species Weld decay • Galvanic current measurement has found its widest applications in water injection systems where dissolved oxygen concentrations are a primary concern. Oxygen leaking into such systems greatly increases galvanic currents and thus the corrosion rate of steel process components. Galvanic monitoring systems are used to provide an indication that oxygen may be invading injection waters through leaking gaskets or deaeration systems.

Hydrogen Monitoring • Hydrogen Monitoring provides an indaction that corrosion is taking or has taken place • Plants or pipe lines that are exposed to wet sour gas (H 2 S) or acid conditions the generation of Hydrogen is a primary concern • The concept of hydrogen probes is to detect the amount of hydrogen permeating through the steel by mechanical or electrochemical measurement and to use this as a qualitative indication of corrosion rate.

Weight Loss Coupons • The Weight Loss technique is the best known and simplest of all corrosion monitoring techniques. The method involves exposing a specimen of material (the coupon) to a process environment for a given duration, then removing the specimen for analysis. The basic measurement which is determined from corrosion coupons is weight loss; the weight loss taking place over the period of exposure being expressed as corrosion rate. • The simplicity of the measurement offered by the corrosion coupon is such that the coupon technique forms the baseline method of measurement in many corrosion monitoring programs.

Weight Loss Coupons • The technique is extremely versatile, since weight loss coupons can be fabricated from any commercially available alloy. • Localized corrosion can be identified and measured. • • Inhibitor performance can be easily assessed. • Therefore, coupon monitoring is most useful in environments where corrosion rates do not significantly change over long time periods. However, they can provide a useful correlation with other techniques such as ER and LPR measurements. •

Non-Destructive Testing Techniques (NDT) • NDT instruments includes ultrasonic, radiography, thermograph, eddy curent measurement

Analytical Techniques • Analytical Techniques usually involves drawing off a fluid sample. This sample is sent to a laboratory for analysis • The common analysis will look at Ph levels, iron and chlorides counts, oxygen and conductivity

Pitting Factor & Corrosion Rate

Non Intrusive Sand Monitor

Intrusive Sand Monitor

MITIGATION OF MIC Water Treatment • • • Most Common Approach Preventative and Remedial Flexibility Costs Personnel Safety Environmental Concerns

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