A general system of determining corrosion rates is by using corrosion coupons, which are uniform in size, pre-measured pieces of metal. Corrosion coupons, illustrative of system metals, are implanted into a coupon rack set up on the system to be observed. Commonly, system water is allowed to pass over the corrosion coupons for around 30 – 90 days. The coupons are then removed and given back to a lab where they are purified and re-weighed. From this weight reduction and the estimations of the coupon, a corrosion rate in mils/year (mpy) is found out. 1.0 mil/year changes over into 1/1,000th of an inch of metal wastage consistently.

The below mentioned portrays different sorts of attack that can be seen on coupons:

Generalized Attack – Uniform corrosion on entire surface of the coupon. Not normally a stress unless the mpy is expanded.

Corrosive Attack – A typical term given to any incision on the metal surface caused by corrosion. Pits can vary essentially in size, depth and thickness. Under 10 pits for each side is seldom called isolated corrosion.

Accurate assessment of corrosion rates in any sort of environment is vital when seen as far as upkeep and repair costs associated with corrosion and material lapse. Test coupons give a fair means for on-line observation that will allow you to satisfactorily evaluate the destructiveness in your system. By scrutinizing at the mils-per-year corrosion rate of a revealed coupon, important information can be given as regards to the material’s durability.

Crystal Industrial from India can make coupons in any size, frame, or material you demand. Coupons can be stenciled with metal mix and arrangement of numbers for proper recognition. Process test reports, recognizing component blends of materials used, are given on all demands.

While asking for test coupons, please make a special effort to be prepared to provide the representative with information in regards to the material you are analyzing, the style and size of the coupons you require, surface finish needed and if suitable, mounting opening size and region.

Corrosion rates can vary among welded and non-welded metals, therefore it is suggested to monitor the behaviour of both the conditions. Studies involve investigation of the parent material, the thermal affected zone, the weld metal, and the interfaces between all metals incorporated. The surface effects produced by welding, formation of thermal-tint or oxidation, fluxing action of slag, and the deliquescence of slag can be critical parameters in the corrosion reaction of metals.

Ideally, the coupon used must be a corresponding thickness and welded with an identical welding process from the material used in the production instrument. By and large this is not reasonable so an illustrative sample must be analyzed.

Specimens are ground smooth followed by welding, unless usually signified, to give a uniform surface for microscopical analysis.

Finishes

Crystal Industrial’s Coupons from India can be furnished with a variety of finishes as per your particular application. Maybe a couple of typical finishes acquirable are described underneath:

Mill – finish as fabricated from plant.
A coarse belt normally used in corrosion analysis, for instance, pitting reviews, where uniform surface finish is needed.

Twofold Disk Ground – super fine finish using a coarse disc that leaves insignificant accumulation. Good for scrutiny where surface finish is essential.