Transcript Corrosion/Erosion

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)
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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.
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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
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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
(H2S) 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.
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• 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.
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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
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Most Common Approach
Preventative and Remedial
Flexibility
Costs
Personnel Safety
Environmental Concerns
BIoGEORGE PROBE
1.500"
EPOXY
2.250"
304L SS
or
Titanium
2" NPT
304 SS
or PVC
BRASS STUD
6 Pin Sealed Connector
97292r1