Recognized for 40 years, the French company, CMI Sleti is one of the main suppliers of tailor-made surface treatment lines and workshops active in the fields of aeronautics, automobiles, luxury goods, construction, armaments, and many other industries; since 2015, it has been part of the prestigious Belgian group John Cockerill. The final customer, a French research center, needed an access solution for the maintenance of the new storage tanks used in the factory. CMI Sleti was supported by the design and production capacity of P-Trex, a business unit of Fiber Net Spa
P-Trex specialises in the design and production of profiles, structures and fences in composite material (GFRP), which are used in many industrial sectors as an upgrade to replace conventional materials. All the P-Trex profiles and structures are produced by Fibre Net Spa, a leading company in the market for structural reinforcement, strengthening, improvement and seismic retrofitting of existing buildings and infrastructures.
The solutions, proposed by the P-Trex team, are tailor-made to customer specifications and aimed at solving the critical issues commonly found in the areas they encounter. In this case, the proposed solution was the result of a detailed preliminary calculation supported by in-depth analyses to verify compliance with European regulations, providing the customer with a complete project. The preliminary calculation, based on real weights and measurements, highlights the resistance capacity to specific loads and indicates which profiles are best suited to the construction of the structure.
Given the specific operating conditions, the need arose to combine a traditional material like steel with the pultruded profile structure. P-Trex’s ability to devise a high-performance solution is not just limited to assessing the use of the material of which it is a specialist, but also to extends its expertise to combining different materials, both traditional and modern, to find the best combination based on their use.
The final project resulted in the creation of a hybrid structure, consisting of a load-bearing part in traditional material and a part intended for access and walkways in GFRP (glass fibre- reinforced plastic). The goal and expected benefit coincided in the stability of the structure, which is resistant to earthquakes, wind loads and the sloshing of the liquids in the tanks. The structure was sized to support a load of 100 tons.
From the design stage, P-Trex moved on to the production of an access staircase consisting of two flights, with an intermediate landing, measuring 4.5 metres in height and a 10-metre-long walkway, raised above the structure in traditional material, to allow access for tank maintenance. While the main parts in GFRP were pre-assembled before being shipped, the load-bearing part was assembled on site, together with the grating panels for the walkway.
P-Trex guarantees customer support at all stages of the design, even when additions to the initial project are required with upgrades or simply additional details. Indeed, one week after installation, the team designed and supplied the customer with GFRP gates for the stairs and access parts, designed for simple and flexible assembly on site, without modifying the original structure.
Lightness and modularity are the two main benefits of using GFRP, both on its own or when combined with traditional materials in a hybrid structure. Even if large in size, GFRP stairs and walkways are easy to transport and, thanks to their modularity and adaptability, are easier and faster to assemble. This results in ultra-rapid installation.
Moreover, compared to an alternative structure made entirely of traditional material, GFRP products provide excellent mechanical performance combined with high resistance to corrosion, all factors that contribute to prolonging the useful life of the structures and minimising maintenance.