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Tag Archives: virgin rubber

RUBBER QUALITY: UNDERSTANDING THE IMPACT

The issue of rubber quality in fender systems is one that the market cannot continue to be complacent about.

A best writing paper typical fender system is constructed from both steel and rubber, and whilst the steel component will, rightly, undergo extensive testing to meet stringent standards, the importance of the fender’s rubber element is often overlooked.

In recent years, there has been a significant evolution in rubber manufacturing industries: we’ve seen the emergence of contract mixers, locations such as China and India becoming mainstream hubs, and the availability of a wider range of ingredients for rubber compounding.

These changes represent a break from tradition, and best practice in rubber compounding needs to keep pace.  The market must take the necessary steps to educate itself on this evolution and understand the effects these changes have on the performance and lifecycle of fenders.

We’ve recently launched a new whitepaper which delves into the issues of Velocity Factor (VF) and Temperature Factor (TF).  First introduced in PIANC’s “Guidelines for the design of fender systems, 2002” they should be applied to rubber fenders at the testing stage, to accurately ascertain performance in the field under varying compression times and temperatures.

Changing rubber compound ingredients have a direct effect on the characteristics of the fender and as such, VF and TF are greatly affected by the type of rubber used, be it natural or synthetic – and within that, virgin or recycled – and further still by the compound composition of the rubber.

VF and TF must be calculated and reported on a case by case basis.  Each is dependent on the make-up of the rubber compound, and as such, there is no “standard” factor that can be applied to calculate and report performance under varying velocities and temperatures. The degree of VF and TF applied will change depending on the rubber compound and, subsequently, from manufacturer to manufacturer.

PIANC’s recommendations for applying VF and TF are really only the beginning.  Suppliers need to make the appropriate investments in R&D to be able to underpin and substantiate their claims. Anecdotally, we’ve found that many actually copy factors which are not relevant to their products.

If suppliers aren’t able or willing to take the necessary steps to understand and be able to guarantee the quality of their products, then it’s essential that specifiers can to avoid throwing good money after bad on systems that are not fit for purpose.

To learn more, download the whitepaper. If you have any questions or comments, we’d love to hear from you in the comments section or via our LinkedIn group.

INTERPRETATION OF TEST RESULTS

Our rubber testing whitepaper “Fenders: why it’s not so black and white” highlights some interesting results from the comparison of the compositions of low cost and high quality fenders – results that clearly highlight dramatically different performance characteristics between the two.

The low cost fenders contained larger amounts of recycled rubber and filler, and were found to be heavier and denser than those that used virgin rubber.

Further chemical and physical analysis revealed some further important results, including:

  • Tensile strength and the value of elongation at break were found to be lower in the low cost fender than in the high quality fender, which was made with higher quantities of virgin rubber.

    Crucially, the low cost fender was not in compliance with the specification.

  • Rubber to filler ratio for the high quality fender was 1.23, for the low cost fender, just 0.88.
  • Overall, the low cost fender contained 28.45% less rubber than the high quality product, explaining the difference in the physical properties of the two and justifying the higher purchase price of the high quality fender.

It’s essential that decision makers are aware of the key performance differences and varying quality being sold as one and the same thing, when they procure fenders based on up front price alone.

These tests provide a reliable analytical method that can be made available to buyers so that they can assess the composition of recently procured fenders prior to delivery, simply by taking a small sample from the surface of the fender.

For more information, download the full rubber testing white paper here.