Much more than a berth protector
Dave MacIntyre finds out why fender evolution has demanded a review of current best practices
Marine fenders are a critical component in maritime infrastructure, absorbing the energy of vessels during berthing and while moored, and protecting ships and berth structures from damage.
But changes to materials and use, in addition to new technologies, have rendered guidelines on best practice out-of-date, prompting an industry-wide review of specifications.
The World Association for Waterborne Transport Infrastructure (PIANC) has taken up the mantle through a new working group (MarCom WG 211), which has been tasked with updating the association’s 2002 Guidelines for the Design of Fender Systems. The working group’s target is to provide a complete tool for users, designers and contractors.
The working group was launched at PIANC’s MarCom (Maritime Commission) meeting in October and already, there is great interest from fender suppliers and ports.
Francisco Esteban Lefler, PIANC’s chair of MarCom, says that after 16 years and a lot of new development in this field it is time for a deep review: “I would not qualify the existing report as obsolete, but a reviewed edition will be a great help for PIANC members and stakeholders … the evolution is very fast.
“Many of the data extensively used for design [such] as berthing velocities are relatively ‘veteran’. This does not mean that they are wrong, but it is time to gather a lot of information that has been produced since 2002 and integrate it in the new report.”
Additionally, new topics have been introduced to the revised report such as durability, maintenance and repair, implications of automated mooring systems, design of additional components of the fender system such as facing panels, chains and fixings, and so on.
“There are new and more efficient materials and topics such as durability, sustainability, ageing and life-cycle assessment that will be addressed,” says Mr Lefler. “Performance of new materials will influence energy absorption and subsequent berthing forces. Additionally, sustainability considerations are expected to be addressed, the potential of re-use and recycling, etc.”
While PIANC is not a certifying body and does not recognise any certification based on its reports, there has been a great deal of interest from industry in the work of WG 211. US-based McLaren Engineering Group for one is intending to make submissions.
Porang Deljoui and Matthew McCarty, senior project managers for McLaren’s Marine Division, say that despite being 16 years old, the existing WG 33 is one of PIANC’s most referenced guidance documents and should be updated to stay relevant with current practice.
“We have noticed changes in recent years by using synthetic rubbers, and blends of synthetic rubber with natural rubber, which present a better E/R ratio (higher energy absorption to reaction ratio) in the same environmental conditions compared to older blends and natural rubber.
“We also noticed higher velocity factors and temperature factors (especially for colder temperature). These modification factors are noticeably higher than previously-reported values by the same suppliers and are more noticeable for synthetic and blend compounds.”
The McLaren managers say that some suppliers do not provide this data for different compounds, so the comparisons are sometimes made just based on published data only.
They add that most clients like independent testing, as they have greater confidence in performance of delivered products versus tests being performed directly by the supplier and as such would welcome additional guidance from PIANC on how best to utilise independent testing and verification of fender products.
McLaren would also like WG 211 to address the issue of suppliers using the terms “PIANC certified” or “PIANC approval”.
Trelleborg has also welcomed updated guidelines that would see a stricter line on the use of PIANC’s name in those terms.
Richard Hepworth, president of Trelleborg Marine Systems, says: “Ports need to have the confidence that their equipment is fit for purpose to fully protect terminals and berthing vessels, while keeping the port running safely and efficiently.
“However, as the economy has become increasingly global, it is more difficult to be fully confident in the performance and provenance of some products. Some unscrupulous suppliers are taking the opportunity to undercut reputable fender manufacturers. We have been working for years to prevent this.”
Mr Hepworth says Trelleborg has spent eight years lobbying for updates to the guidelines with substantial investment in research highlighting the importance of understanding how ingredients for fenders are selected, how they are manufactured and how they are tested.
The company “relishes discussion of its research into rubber compound composition, velocity and temperature factors, manufacturing methods and testing”.
ShibataFenderTeam (SFT) also welcomes the new PIANC research. SFT board member Dominique Polte says the industry forgets that fender systems consist of more than just the rubber fender – steel panels and fixing material, and the overall engineering in combination with the substructure, are equally important.
“The quality and durability of all elements and their engineering make the difference between a high- and low-quality product and between an experienced fender manufacturer and one without a proven track record.
“There needs to be updated standards as well for panel design, panel internal structure calculations, chain position and angles, anchors’ edge distances, corrosion protection methods, and UHMW-PE quality requirements.”
SFT is also hoping to see an upgrade of testing and verification, with clear and precise test procedures, testing according to the same standards and probably doing verification of the scaled model at selected verified test labs.
“One of the main issues that the old WG was not able to conclude upon is to set new rules for determination of velocity factors for fenders. There is consent among WG members that this is needed and needs to be addressed in the new WG.
“We hope that especially correction factors will be defined more precisely to secure that fender manufacturers test all of their products on the same basis to ensure the comparability of products.”
SFT would also like to see more information about foam fenders and a section on parallel motion fenders.
“All our changes focus on not compromising the independence of PIANC and we hope all WG members follow the same code of ethics,” states Mr Polte.
He adds that there is another topic which is a priority for SFT: the worrying change of focus when talking about fender design and fender quality. There is no international standard specifying the chemical composition of the rubber compound used in rubber fenders, and using reclaimed rubber limits their durability, he says.
“We noted a shift to an increased focus on the ratio and amount of ingredients used for the rubber compound and a misleading correlation with quality. No doubt, the development of a compounding recipe is one of the most sensitive parts of fender production. However neither the ingredients alone, nor their ratio, prove high or low quality.”
Mr Polke is concerned that if the rubber composition of only one manufacturer enters into an international standard (new PIANC guidelines) this will be a competitive advantage for them over other manufacturers, without bringing any quality advantage to the industry.
“We therefore hope the update of WG 33 … keeps its focus on testing, verification and design guidelines without interfering in the production process of manufacturers.”
TIMELINE FOR FENDER UPDATES
PIANC first published guidelines for fender designs in 1984 and followed in 2002 with PIANC WG 33, which included more advanced fender design and testing methods, taking into account performance modification factors for manufacturing tolerances, temperature and velocity.
However, since the WG 33 guidelines were published there have been further advances in design methods for fender systems and evolution of vessel dimensions and hull shapes. Analysis of berthing velocities and angles has been conducted, and another working group (WG 186) is currently considering mooring requirements for large ships at quay walls.
Manufacturers have undertaken further research into fender materials, performance, durability and impacts of aging and now improvements to WG 33 guidelines have been suggested by users.
This includes improved fender testing and verification procedures, performance requirements for fender system elements and the addition of maintenance and repair guidelines.
WG 211 is therefore being tasked with a general update of WG 33. The group will also review recent research by fender manufacturers and update guidance in relation to durability and performance, including the composition of fender materials and influence on performance factors and durability, causes of failure, and the impact of ageing on fender performance.
There will be specific reference to areas such as the consistency of test procedures and compliance in testing facilities, the representative quality and quantity of samples to be tested, the independence of testing and verification of fender materials and performance, and guidance on design of other fender system components.
The intended outcome is concise and clear design guidance for fender systems.
The official timeline for PIANC working groups is two years but this group will focus more on quality than on a tight schedule.
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