Different corrosion techniques

Corrosion techniquesDifferent corrosion techniques Non Destructive Testing Analytical Chemistry Ultrasonic testing Radiography Thermography Eddy current/magnetic flux Intelligent pigs Analytical Chemistry pH measurement Dissolved gas (O2, CO2, H2S) Metal ion count (Fe2+, Fe3+)Microbiological analysis

Different corrosion techniques Corrosion Monitoring Weight loss coupons Electrical resistance Linear polarization Hydrogen penetration Galvanic current

Fluid Electrochemistry Potential measurement Potentiostatic measurements Potentiodynamic measurements A.C. impedanceMostly used techniques Corrosion coupons: This is one of the effective and easy method for the corrosion monitoring techniques.It consists of the metal coupons connected to the holder The principle of this technique is measuring of the weight loss of the coupon after the exposed to the environmentIt can record several type of corrosion which cant be done by most of the different methods

Mostly used techniquesFrom the corrosion couples we can obtain theCorrosion ratePitting rateWeight loss Corrosion rate depends on the faraday lawWeight of metal dissolving (g) = K x I x tK = (atomic weight of metal (g/mol))/ No. of electrons transferred * 96,500 Amp/Sec where: I = current (amps), t = time(sec)Pitting rate Pit (mpy) = (pit depth(mils) x 365)/exposure time in days

Mostly used techniques Electrical resistivity (ER)The principle of this technique is measuring the change in the resistance R= r*(L/A) Reduction in the elements cross section due to corrosion will be accompanied by a proportionate increase in the elements electrical resistanceIt consists of 3 parts they are working element, reference element, check elementIf the resistance difference between check element and the reference changes the probe is not working properlyMostly used techniques

Mostly used techniquesFrom ER we can obtain the metal loss and corrosion rate Metal loss(M)= (S*P)/1000 where S= linearized Signal P= probe lifeCorrosion rate(C)=(P*365(S2-S1))/( T*1000) Mostly used techniques Linear Polarization Resistance(LPR)In this we will measure the relation between the electrochemical potential and current generated between the electrodesThe electric conductivity of a fluid can be related to its corrosiveness R= V/IDuring this process only small current so we will provide external potential of 20mVto the process Mostly used techniques UltrasonicThis method is used to detect the general corrosion and erosion In this method the transmitter produces the sound wave and these travel through the samples If there is any defects or corrosion there is change in the reflected sound waveFrom the information we can know the hidden corrosion and the depth Mostly used techniquesEddy currentThis technique is used only to the conductive elementsWe will pass the eddy currents through the metal If there is any corrosion there is fluctuation in these currents these are used to detect the hidden corrosion