Description

The function of a corrosion coupon is to regularly monitor the degree of corrosion in the pipeline and measure the corrosion rate. The corrosion coupon is a sheet metal block prefabricated with the same material as the main process pipeline, and the metal sheet is suspended inside the pipeline to be tested using a suitable suspension piece. Make the corrosion plate and the inner wall of the pipeline withstand the same corrosion conditions, after a certain period of time, the hanging plate is taken out and re-weighed, and the corrosion rate is calculated by the formula so that a more accurate corrosion situation of the inner wall of the pipeline can be obtained.

Corrosion coupons are an inexpensive and effective way to monitor the rate of corrosion of any system or structure. However, getting useful results from testing is not as simple as measuring weight loss and using a formula to calculate the average corrosion rate. Surface polishing, mounting placement, and test time all significantly affect the quality of the data. Here is an overview of corrosion mount testing and how to get the most reliable data.

Corrosion hitch testing is an internal pipeline monitoring technique where the hitch is placed directly in industrial fluids and removed for measurement. This technique provides a direct measurement of metal loss and then calculates the average corrosion rate. When corrosion coupons are used, the results do not depend on the phase of the measured fluid.

Benefits of corrosion mount testing.

1. Simple and direct

2. You can also check the specimen after the test

3. Allows comparison between different alloys and corrosion inhibitors

4. Suitable for all forms of corrosion

Corrosion coupons are most commonly used to measure uniform corrosion and calculate the average corrosion rate based on the weight loss of the hangers. However, other forms of corrosion can also be performed using the hanging chip test:

Crevice corrosion – Special washers/spacers can be used to simulate crevices where the surface of the hanging piece is free of liquid intrusion.

Pitting – Pitting on a mount can be evaluated visually or microscopically. Use a large surface area because the initial number of spots is proportional to the surface area of the hanging piece.

Additional uses for Corrosion coupon analysis

Protect you from complaints of poor quality corrosion control systems from competitors. A competitor may try to doubt the effectiveness of your corrosion control system. By placing a hanger in the process and using your inhibitor, then compare the surface of the hanger and the weightless plate which is hung by copper wire in a high-speed pipe, while your competitor’s coupon is fixed to an insulating rod and placed in a deoxygenated environment. Compared to the effects of using his chemicals. See where these hangers are placed in the flow, probably the hangers in your flow

Monitor the effectiveness of your seller’s corrosion control system. If you hire a vendor to conduct corrosion monitoring services, setting up 35 of your own hangers to evaluate their results may be a cost-effective way to save money and ensure that you are getting what you are paying for.

Monitor cleaning procedures and shutdowns. Placing the coupon in the process during cleaning or closing and removing it before starting can identify corrosion damage occurring during this time.

The hanging test is widely used as an important means to detect and monitor the corrosion of specific materials or media. The authenticity of its data will directly affect the relevant research results and the applicability of corrosion prevention measures, such as corrosion inhibition research and evaluation. As an important part of the method, the quality of corrosion couponwill have an important impact on the data.

The corrosion test (hanging) piece is hung in the test container, on the field test heat exchanger, or on the test pipe, the standard metal test piece used to measure corrosion. Used to detect or evaluate the corrosion status of the cooling water system. Generally, the pre-treated and weighed metal test pieces are placed in the test system for a period of time (such as 30 to 90 days), or the same group of test pieces can be taken out at different times, such as 30 days, 60 days, 90 days, etc. During long-term observation, 12 or 24 test pieces were put in each time, 1 or 2 pieces were taken out every month, cleaned, and weighed to determine the weight loss degree of metal corrosion (using tragus juice, lumpy = 0.0254rnmla), corrosion type and pitting depth, etc., respectively to measure the corrosion speed, and then the corrosion speed time curve was drawn.

The monitoring time of corrosion test pieces is generally 30 to 90 days, or the same group of test pieces can be taken out at different times, such as 30 days, 60 days, 90 days, etc. During long-term observation, 12 or 24 test pieces were put in each time, and 1 or 2 pieces were taken out every month to measure the corrosion rate respectively. Finally, the corrosion velocity-time curve is drawn.

Preservation and use method

1. The standard corrosion coupon (corrosion measuring hanging piece) in distilled water with degreasing scrub again, and then rinse with distilled water for 15 seconds;

2. The standard corrosion coupon (corrosion test hanging sheet) in chemical pure anhydrous ethanol (50ml/ every 10 pieces) with degreasing scrub twice;

3. The standard corrosion coupon(corrosion measuring hanging piece) is placed on the drying filter paper and dried by cold air;

4. The standard corrosion coupon(corrosion measuring hanging piece) is wrapped in filter paper and placed in the dryer. After 24 hours, it is weighed and ready for use.

5. Place the original package test piece in a place without corrosive gas and keep it moisture-proof;

6. The standard corrosion coupon(corrosion measuring hanging piece) that has been opened and not used up should still be placed on rust-proof paper and placed in the dryer.

7. The installation position of the piece hanger can be determined according to the test purpose. Priority should be given to sites with the most severe corrosion and representative dissolved oxygen content.

8. Attention should be paid to the changing direction of the test piece in the system so that the corrosion products will not be scattered on the adjacent test piece.

9. The hanging position of the test piece should be relatively fixed, and the test pieces in the same part should be in the same environmental conditions. 10. During installation, it is not allowed to touch the hung test piece with your hands or other dirt.

corrosion coupon