Hydraulics & Pneumatics Magazine July/August 2025

HYDRAULICS 16 HYDRAULICS & PNEUMATICS July/August 2025 www.hpmag.co.uk Swaging hydraulic hoses requires more than a visual fit In hydraulic hose assembly, combining components from different manufacturers might seem like a practical solution, especially when parts appear to fit together and stock availability is limited. However, this practice introduces a layer of uncertainty that can undermine the reliability of the entire system. Hoses and fittings may look compatible, but small differences in dimensions, materials, or design standards can affect the performance of the assembly in ways that aren’t immediately obvious. Problems often only emerge once the system is under pressure, by which point the consequences may already be costly. Manufacturers of hydraulic hoses and fittings typically design and test their components as a complete system. This means that the tolerances, crimp dimensions, material properties and performance under pressure are all verified based on specific combinations of hoses and fittings from the same brand. When components from different manufacturers are paired together, even small differences in internal diameter, outer cover thickness, or fitting insertion depth can lead to improper sealing, inconsistent crimping, and ultimately a failure to maintain integrity under pressure. Swaging process These issues are particularly relevant during the swaging process, where exact tolerances and die selection are required to achieve a safe, secure connection. Swaging, the method used to permanently attach fittings to hydraulic hoses by applying radial compression, relies on precise compatibility between hose and fitting. Using non-OEM components disrupts this relationship. Crimp dimensions provided by one manufacturer may not suit another’s fitting geometry, which can result in under- or over-crimping. This undermines the entire purpose of the swage, which is to produce a uniform, reliable seal capable of withstanding significant pressure. UK industry guidance, including BS EN ISO 4413 and ISO 12100, supports the principle that components in fluid power systems must be appropriately selected, assembled, and maintained to ensure safety and reliability. Mismatched parts compromise these principles. This is particularly important in highpressure applications, where even a minor deviation in fit or crimp geometry can result in leaks, blow-offs, or hose bursts. These failures are not only expensive in terms of downtime and repairs but also pose risks to safety and the environment. Hydraulic systems are used in a wide range of industries, from construction and agriculture to aerospace and manufacturing, and any unexpected failure can have knock-on effects far beyond the immediate repair. The UK has robust regulations in place concerning machinery safety, and while there is no outright legal ban on using non-OEM parts, failure due to mismatched components could potentially breach health and safety obligations, particularly under PUWER or the Health and Safety at Work Act. The issue is compounded by the fact that many failures caused by mismatched components are difficult to trace after the event. Once a hose has failed, particularly if it has been removed from service, it can be challenging to determine whether the fitting was incorrect or whether some other factor contributed. This makes prevention all the more important. Best practice among reputable hose assembly facilities in the UK is to use matched systems only, or if using a mixed system, to obtain explicit compatibility confirmation from manufacturers. However, this is not always adhered to, particularly in field repairs or smaller workshops where the focus is on fast turnaround rather than traceable conformity. Another concern is the erosion of warranty and certification coverage. Most hose and fitting manufacturers clearly state Mismatched hoses and fittings may appear to fit, but they compromise the precision swaging relies on. H&P explores how using non-OEM components in hydraulic assemblies introduces hidden risks, affecting safety, warranty, and long-term reliability especially under pressure, where exact compatibility between parts is critical to performance and compliance.

RkJQdWJsaXNoZXIy MjQ0NzM=