A leading South African manufacturer of paper-making equipment sought to modify an existing pulp machine and turned to trusted partner SKF to assist with the redesign of a critical sealing arrangement. With a longstanding track record of successfully using SKF’s high-performance bearings, seals and couplings, the customer turned once again to this proven source for an expert, precision-engineered solution.
The application involved a paper/pulp washing and compression box equipped with a rotating internal shower system which is designed to generate internal pressure while also cleaning the machine. A sealing solution was required that is capable of withstanding 1 bar of pressure and that can also offer strong resistance to corrosion.
Collaborating closely with the customer, the SKF team combined their expertise to develop a straightforward, effective, reliable and easy to implement solution that met all the requirements – a customised sealing arrangement and bearing unit mounted externally on the shower to prevent water leakage during rotation. Nthavela Makondo, Application Engineer at SKF, explains that in order to accommodate the bearing unit’s critical function in facilitating the shower’s rotation, it was essential to customise the sealing arrangement.
“Using the correct seal type and materials were also critical to ensuring an optimum solution, so the sealing arrangement we engineered comprised stainless steel components, locally manufactured seal retainers, O-rings and precision-machined seals,” states Makondo. Andre Weyers, Seals Sales Manager at SKF, played a key role in both selecting the appropriate machined seal type and in specifying a self-lubricating material – stainless steel was chosen for its excellent corrosion resistance, especially in wet, chemically aggressive environments – ensuring enhanced performance.
Makondo details the solution further: “We added an O-ring on the side to prevent water from seeping between the tank wall and the seal retainer, which could otherwise damage the welds. The complete sealing assembly was delivered with a FT 60 TF bearing unit. Our choice of bearing unit size was based on the shaft or shower diameter, along with the load specifications provided by the customer.”
The implementation of the tailored sealing arrangement brings a range of significant benefits for the customer: With a factory-greased bearing sealed for life, reliability soars and the machine’s lifespan is significantly extended. Furthermore, reduced maintenance means greater uptime, while environmental gains include cutting water use and minimising grease waste.
Having received the go-ahead from the customer at the end of January 2025, the SKF team completed the locally manufactured sealing arrangement within just three weeks. The solution was delivered to the customer’s site in March, installed two months later and successfully commissioned on October 1st, demonstrating a seamless integration of teamwork, experience and know-how. “Since the customer needed to integrate our design into their system, they took responsibility for both the installation and commissioning of the machine because it was part of a larger project at the plant,” explains Makondo.
SKF’s specially designed sealing arrangement, combined with the FT 60 TF bearing unit, provided the optimal solution to combat high-pressure conditions and aggressive corrosion, ensuring the exceptional durability and performance of the pulp machine. Given that the machine has been in operation for over 20 years, modernising its functionality and extending its service life is a proud achievement that not only highlights the SKF team’s technical expertise and dedication but also bolsters the machines continued reliability and efficiency, ensuring it remains a valuable asset for the customer.
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