TPT September 2022

AR T I C L E

Quaker Houghton

Corrosion – at what cost? According to the “Corrosion Costs and Preventive Strategies in the United States,” a 2002 study commissioned by the Federal Highway Administration, undertaken by CC Technologies Laboratories Inc, and sponsored by NACE International, the direct costs of metal corrosion in the US total $276bn annually. To put this into perspective, it amounted to more than 3 per cent of US gross domestic product. Corrosion comes with another cost. A manufactured component or assembly that fails, or requires a remedial corrosion prevention treatment, results in customer dissatisfaction. Using comprehensive corrosion control methods is critical in minimising both types of costs.

• The salt spray cabinet test (ASTM B117) exposes specimens to a 5 per cent salt spray in the form of a fog; the temperature is maint ined at 100°F. • The GM 10-cycle test, developed by General Motors to evaluate corrosion preventives, has been adopted by many suppliers aligned with GM. This method is similar to the JAN but it runs at 100°F in a non-condensing environment. In addition, it runs 10 cycles, each cycle consisting of 18 hours in the cabinet and 6 hours out of the cabinet. Troubleshooting When you first investigate a rust issue, it is important to learn the metal surface’s exposure history; you need to trace back through all of the processes to determine where the corrosion began. The investigation should involve every process and fluid that contacts the parts. Only by tracing the entire process do you have a chance of determining the application that has the greatest impact on the corrosion problem. The fluids involved in the process should be evaluated for fitness for use relative to fresh fluid. Cause-and-effect diagrams can help you find the root cause (see Figure 2 and Figure 3).

Shandong Province Sifang Technical Development Group

ENVIRONMENT

CHANGE IN PROCESS

PRODUCT

Low Concentration

Depletion of Rust Inhibitors

Wrong Alloy for Process

High Humidity

Large Water Adds

Improper Test Method for the Concentration

Insufficient Coverage of Fluid on Part

Location Prone to Dust, Fines

RUST

Hardness

Tramp Oil

Fines or Dirt from Previous Process

Chlorides

Unimpeded Microbial Growth

Sulfates

CONTAMINATION

POOR WATER QUALITY

Figure 2: Finding the cause of corrosion does not need to be a daunting task. Breaking the causes down into five broad categories gives you a starting point

SUBSTRATE

PRODUCT

Low Concentration

Pre-Existing Rust

Contamination

Surface Chlorides

High Moisture

Residual Contamination from Poor Cleaning

Oxidation Due to Excess Heat

PROBLEM WITH A CORROSION PREVENTIVE

High Bacterial Growth

Moisture on Surface

Improper Packaging

Improper pH Level

High Mineral Content (Hard Water)

Uneven Coating (Dewetting, Clogged Nozzles)

Sulphates

Atlanta 2022, Booth B5159

Unfavourable Storage (High Humidity, Acidic Atmosphere)

Chlorides

Contamination

Low Coating Weight

Quaker Houghton www.quakerhoughton.com

MAKE-UP WATER

APPLICATION

Figure 3: More troubleshooting details can help you hone in on the problem area

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SEPTEMBER 2022