Compounding – A Winding Road

ShibataFenderTeam Group releases first White Paper on rubber compounding

Safety, reliability, durability – the performance requirements of a marine fender boil down to these three aspects, and rightly so. Fenders are meant to create a safe environment for ships and passengers while protecting port infrastructures and all personnel working there – reliably during the design life and beyond. This is the ideal that ports and port operators strive for.

When considering the product features required for such high performance, waters tend to become somewhat murky. There are international standards and guidelines providing guidance as to the physical properties of rubber fenders – like PIANC2002 and ASTM D2000. However, there is no international standard specifying the chemical composition of the rubber compound used in the manufacturing of rubber fenders.

Industry standards are delineating a clear goal in the manufacturing of marine fenders, their performance, physical properties and durability, but there is no recommendation as to how to get there. The reason for this is simple: no two fender projects and no two fender manufacturers are alike. Each project has unique requirements that necessitate customized rubber compositions.

All of this provides a lot of room for market differentiation and opportunities for fender manufacturers to present their own best practice-approaches to producing high performance products. Yet, it has also become the breeding ground for some widely accepted – and by some stakeholders actively advocated – misconceptions about compound production, the most prevalent one asserting that the quality of a fender is primarily determined by the chemical composition of its rubber compound.

“At the ShibataFenderTeam Group (SFT), we believe that the quality of a fender should be measured by its performance, i.e. by the degree to which a fender lives up to the requirements of its specific field of application,” says Mr. Dominique Polte, Board Member ShibataFenderTeam Group.

As a reinforced rubber compound is the core of any fender, the first part of the SFT White Paper Series on fender manufacturing “Compounding – A Winding Road” focuses on the raw materials used in rubber production, the physical properties of a fender, and their correlation with the compound’s composition. Its goal is to detail the considerations relevant to determining what makes a good fender.

It finds that in fender manufacturing, physical properties are the only reliable indicator of the quality of a rubber compound that is defined by international standards. In addition, the white paper recommends that ratios of fillers and reinforcement agents such as carbon black (CB), calcium carbonate (CC) and silica should be determined by specialists with profound material knowledge, as amount and particle size greatly influence the compound as well as its performance and durability. Furthermore, the paper draws attention to the fact that rubber compounds mixed correctly with CC by experienced manufacturers comply with and surpass international testing standards.