Cathodic protection snapshot

Name of technique

Cathodic protection

Use

Prevent corrosion
Complement protection given by coatings

Definition

A technique where an ionic current towards the structure from the electrolyte is used to counter the corrosion current flowing out of the structure.

CP criteria

CP potential of -850 mV vs. CSE
An instant off potential of at least -850 mV vs CSE
A minimum 100 mV polarization post instant off

CP measurement techniques

Soil resistivity
CIPS
DCVG
Line current

Factors affecting CP requirements

pH
velocity
ionic type
ionic concentration
temperature

Issues with CP

Stray current corrosion
Insufficient CP potential
Insufficient CP current
Electrical shorting

I will discuss all these with examples in this major course, where you can prepare for the basics for your certification course!

Check out the introductory video for the brand new course and click on the link to access!

https://corrospective.com/courses/basics-of-cathodic-protection-cp-in-oil-and-gas-industry

Practice your CP knowledge here! Check out Quiz 1!

😀Happy learning!😀

Comments

Corrosion in fertilizer industry - 1.2 Elemental sulphur attack

WATCH THE VIDEO HERE OR READ ON BELOW! Elemental sulphur attack is NOT sulphidation or hydrogen sulphide corrosion. It is an aqueous corrosion phenomenon. It considers two modes - acidification of sulphur - formation of sulphuric acid 2. direct cathodic reduction of sulphur with anodic dissolution of iron The lowering of pH is the main source of corrosion in both the methods. The phenomenon is temperature dependent. It increases with increase in temperature and becomes particularly severe above the melting point of sulphur (~112.8 degree Celsius). Hydrogen sulphide present in the petroleum may aggravate the sulphur attack by enhancing uniform pitting corrosion. Monoethylene glycol is used to prevent condensate formation ans may be present in traces in the feedstock petroleum. This enhances the sulphur attack in the form of uniform corrosion, and crevice corrosion. References: Fang, Haitao, Brown, Bruce, Young, David, and Srdjan Nešic. "Investigation...

What is a Corrosion Loop - PART 2 - EXAMPLE

How to prepare a corrosion loop? To prepare a corrosion loop, the person in charge will look at the overall picture and answer the following questions - 1. What is the process? 2. What are the components? 3. What are the materials for each component? 4. What are the common features among them? 5. Where does the commonality end? - This is important as that will mark the beginning of a new corrosion loop. 6. Can I use the same inspection procedure for all of them? 7. Do they corrode/get damaged in the same manner due to the same reasons? WATCH THE VIDEO FOR A DETAILED EXPLANATION - Read part 1 here! https://corrospective.com/ 😀Happy learning! 😀

Coupon test for corrosion inhibitors

Concept Coupon test is used to gauge a material's corrosion rate in a corrosive environment. It is also used to test the efficiency of corrosion inhibitors. Parameters Material - The coupons are made from the same or similar material as that of the actual component Electrolyte - The electrolyte for exposure is the same or similar to the actual environment. Sometimes, coupons are placed in the actual environment with the component, for example in the soil with submerged pipelines. Steps Clean the coupon of any oil/grease/rust Measure the weight of original coupon - W Measure the Area of coupon to be exposed - A. Take photographs and/or optical micrographs of the coupon Immerse the coupon in the electrolyte without inhibitor Note the time of measurement - t. This is decided by the concerned parties or as per the standards followed. Take out the coupon after the time. Take photographs and/or optical micrographs of the coupon Clean the corrosion products off the coupon. DO NOT USE ROUG...

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