Letter to the Editor

The tempting article title of ‘Rubber rating’ (Port Strategy, November 2012) proved to be disappointing as it represented the opinion of one manufacturer who makes a number of unsubstantiated claims about a general decline in standards based upon unpublished tests of unknown fender types obtained from unnamed sources. I would like to present an alternative opinion based on my knowledge gained from a fender and rubber industry career spanning nearly 30 years.

In my view, there is no general trend towards the increased use of recycled materials by the household names in the fender industry. In all industries there are good, bad and indifferent producers and the fender industry is no exception.

Some factories have in the past attempted to mix recycled rubber and increase the percentage of cheap non-reinforcing fillers into their rubber compounds. Whilst performance is undoubtedly lower, the most rudimentary of physical properties’ tests will highlight the difference quickly. Thereafter the client specifications and approvals process should be sufficient to prevent these fenders from ever being delivered or going into service.

The old adage ‘you get what you inspect, not what you expect’ works in all industries and should also be applied to fenders regardless of the brand name, country of origin and apparent trustworthiness of the manufacturer or supplier. There are excellent fenders made in Asia, some poor ones made in Europe or US and vice versa.

It is an uncomfortable fact that some well known manufacturers with high profile brand names do not make all of the rubber fenders they sell. Some are supplying ‘cheap’ fenders made in third party factories where quality is not tested and the products do not perform to the claimed high standards for that brand. This is an abuse of customer trust and would leave many end users distinctly unhappy if they were to become aware of the practice.

At least five fender manufacturers have attained third-party certification showing compliance with PIANC’s 2002 fender testing guidelines for ‘Type Approval’, and/or have made major investments in advanced test presses allowing them to conduct full size, real speed tests on fenders. Such testing and facilities are expensive and clearly demonstrate a long term commitment to higher fender quality and standards.

Only one manufacturer to my knowledge has adopted and received third party certification of compliance to ASTM F2192-05. This standard goes beyond the requirements of PIANC for ‘Type Approval’ and hopefully more manufacturers will adopt this in future.

The compression set test referred to as ‘proof’ in the afore-mentioned article can be used to differentiate between higher and lower quality materials in well controlled cases only. The compression set method is open to misunderstanding and misinterpretation. Results from samples cut and prepared from pre-vulcanised finished products should never be compared with results from samples moulded from previously unvulcanised rubber. It is well documented that the two methods give quite different answers.

Article weight is a highly inaccurate measure of quality. Design features like the size of fixing bolt ‘pockets’, internal steel plate thicknesses etc will have a significant effect on the fender weight.

Mr Hepworth claims to have tested another supplier’s fenders but the assertions made and conclusions drawn are meaningless without openly declaring test methods and publication of results which are also independently verifiable. An equally valid conclusion could be that some companies have higher operating costs and overheads which they seek to pass onto their customers, or more efficient fender geometry which extracts more energy per kilo of material.

I would urge any reader of your article to ensure they have a good fender specification (PIANC’s 2002 fender guidelines have a good generic template in Appendix ‘E’) and to ensure required standards are properly enforced, and third party verified. Wherever possible inspectors with directly relevant fender test experience should attend the factory or units taken to an independent facility for re-testing.

Mike Harrison
Inshore Systems Ltd