Corrosion Coupon For Testing

Description

Description
The corrosion coupon is hung in the test vessel, on-site inspection heat exchanger, or test pipeline. And it is a standard metal coupon for corrosion determination. It can detect or evaluate the corrosion condition of the pipeline systems. Generally, the operator will put the pre-processed and weighed metal test pieces into the test system for a period of time. (such as 30-90 days). Then we take it out to observe the corrosion, clean it and weigh it. Determine the weight loss degree of metal corrosion, corrosion type and pitting depth, etc. (With tragus auratus juice, lumpy = 0.0254rnmla). Corrosive medium not only affects the data of metal coupon but also related to many factors. Such as the surface treatment of the coupon, placement position, exposure time length, and the sample’s metallurgical method.

Description of corrosion coupon & coupon treatment method
Corrosion Coupons
Storage and use method:
Water treatment standard corrosion test piece, corrosion coupon, cooling water treatment standard corrosion test piece, corrosion coupon, standard corrosion test piece. Corrosion test coupons are processed by professional manufacturers. The materials include an A3 carbon steel test piece, 20# carbon steel test piece, stainless steel test piece, brass test piece, red copper test piece, aluminum test piece, cast iron test piece, etc. Standard corrosion coupon, corrosion coupon specification: type I 50x25x2 storage and use method:

Firstly, wipe the standard corrosion test piece (corrosion coupon) with degreasing in distilled water once. And then wash it with distilled water for 15 seconds;
Secondly, scrub the standard corrosion coupon (corrosion coupon) twice with degreasing in chemically pure absolute ethanol (50ml/ 10 tablets);
Place the standard corrosion test piece (corrosion test coupon) on the dry filter paper and dry it with cold air;
The standard corrosion test piece (corrosion test coupon) is wrapped with filter paper, placed in a dryer, and weighed for use after 24 hours.
Place the originally sealed test piece in a place free of corrosive gas and store it against moisture;
At last, the unsealed but unused standard corrosion test pieces (corrosion test coupon) are still placed in the anti-rust paper and in the dryer.
New coupon treatment (sealed standard coupon)
Immerse the new coupon in absolute ethanol and scrub it twice with absorbent cotton;
Then move it into clean absolute ethanol and soak it for a moment;
Put it on clean filter paper and dry it with cold air;
Wrap it with filter paper, put it in a dryer, and weigh it for use after 24 hours (weighing accuracy to 0.1g).
Treatment of hanging pieces after use
Take out the used Corrosion Coupon carefully, observe and record the surface condition before processing;
If the corrosion deposition is not obvious, wipe it with a drawing eraser to expose the true color of the metal. Then immerse it in absolute ethanol, and scrub it twice with absorbent cotton. And then immerse it in clean absolute ethanol for a moment, take it out, put it on a clean filter paper, dry it with cold air, wrap it with filter paper, put it in a dryer, and weigh it after 24 hours (weighing to the accuracy of 0.1g), get the weight loss, and calculate the corrosion rate.
For the coupon with many corrosive deposits, first, remove the corrosion products by chemical cleaning method, and the mixing system of common chemical cleaning agents explains the rate
Corrosion coupon test method (auxiliary method)
Corrosion CouponScope of application
This method is one of the routine test methods to monitor the relative corrosion and fouling of the cooling water system without shutdown. This method can be used alone, It can also be used with “linear polarization method” and “monitoring heat exchanger method”. The test results are helpful for the confirmation and adjustment of the chemical treatment scheme of cooling water and the evaluation of reagent effect. But generally, the test results cannot be regarded as the reality of the system equipment itself (corrosion, scaling, and fouling). Evaluation of microbial hazards in cooling water system. This should be carried out according to the method specified in Chapter II of this book

Interference factors
In order to get the result closest to the metal condition of the device body, we should consider the main factors:

Firstly, the test piece immersed in cooling water is neither affected by heat transfer nor by steam condensation. Therefore, the test results cannot represent the corrosion of the parts with these two conditions in the system.
Secondly, do not subject the immersed test piece to the action of high flow rate and particles with we arability. Otherwise, the repeatability of test results will be affected.
And then the content of dissolved oxygen in cooling water greatly influences the results. Therefore, we should soak the test pieces in representative parts.
At last, the test piece mainly works for observing the general corrosion forms. But the following special corrosion forms should also be noted In order to be considered in the design and result interpretation:
galvanic corrosion

crevice corrosion;

pitting;

intergranular corrosion;

delamination corrosion (selective etching);

stress corrosion;

the interference of some special trace components in water should be studied in the laboratory if necessary.