www.hpmag.co.uk HYDRAULICS & PNEUMATICS September 2026 25 dimensional inspection and appropriate non-destructive examination. BS EN ISO/ASTM 52920:2023 provides a useful framework for this type of thinking. It establishes requirements for industrial AM processes and production sites and defines quality assurance measures along the manufacturing process. Importantly, it is concerned with the production environment and manufacturing process rather than suggesting that successful inspection of one finished component is sufficient to qualify everything that follows. The significance becomes obvious when production is repeated. Suppose a manufacturer develops an optimised manifold, establishes suitable build parameters, produces test pieces and components, carries out the necessary mechanical, dimensional and pressure testing and obtains satisfactory results. Eighteen months later the same geometry is required again, but it is manufactured on another machine or at another site, using a different feedstock batch and perhaps a revised heat-treatment route. The CAD geometry may not have changed, but that does not necessarily mean the original qualification remains valid. A robust qualification system therefore needs to identify which variables are significant, what limits are permissible and which changes require review, additional validation or requalification. This is particularly important to the prospect of digital inventories and distributed manufacture. Sending an approved geometry file to another AM machine does not necessarily reproduce the qualified manufacturing process that originally sat behind it. Internal inspection Internal inspection presents a related difficulty for fluid power. The ability to manufacture complex internal passages is one of AM’s strongest advantages, yet it removes some of the access available for conventional inspection. Powder removal and internal cleanliness need particular attention because contamination that remains inside a hydraulic component can subsequently enter the system. The appropriate inspection strategy has to reflect the material, geometry, manufacturing process and defects that could realistically occur, rather than relying on a generic inspection requirement applied after printing. There is another regulatory distinction worth making because it is sometimes confused in discussions about pressure equipment. PE(S)R concerns equipment being placed on the market or put into service and covers its design, manufacture and conformity assessment. The Pressure Systems Safety Regulations 2000, PSSR, concern qualifying pressure systems in use at work and the hazards associated with stored energy. They are not interchangeable regimes. HSE specifically notes that hydraulic oils are not relevant fluids under PSSR and that hydraulic systems, while operating at high pressures, are not covered by these regulations. Pneumatic pressure systems containing compressed air can, by contrast, fall within PSSR where the applicable conditions are met. Manufacturers also need to distinguish equipment requiring conformity assessment from equipment falling under Regulation 8 of PE(S)R. Equipment and assemblies within the regulations but at or below the specified classification limits must be designed and manufactured in accordance with sound engineering practice to ensure safe use and be accompanied by adequate instructions. Unless another applicable piece of legislation requires it, such equipment must not carry a UKCA or CE conformity assessment marking under PE(S)R. For equipment requiring conformity assessment, Great Britain permits relevant products to use either the UKCA or CE route, provided the applicable requirements are satisfied. Recognition of CE marking for pressure equipment in Great Britain has been extended indefinitely. Where independent third-party assessment is required, however, the body involved matters. UK Approved Bodies and EU Notified Bodies have different roles depending on the conformity marking route being followed. This is something an AM business entering pressure equipment production needs to establish early, rather than attempting to resolve once the component has already been designed and validated. Standards development is meanwhile moving closer to the particular issues raised by AM pressure components. Work on EN 13445-14, covering additional requirements for pressure equipment and pressure components fabricated using additive manufacturing methods, remains in development. BSI’s standards development programme currently records the project in comment resolution. It should therefore not be treated as a published standard that solves today’s compliance questions, but the work itself is significant. It demonstrates that the relationship between AM process control and pressure equipment manufacture is receiving specific standards attention. None of this makes additive manufacturing unsuitable for hydraulics or pneumatics. Quite the opposite. Fluid power contains applications where the freedom to redesign internal passages, consolidate components and remove manufacturing constraints offers unusually tangible benefits. The danger is assuming that because AM can manufacture a geometry that conventional machining cannot, qualification can somehow be reduced to proving that the finished shape is correct and that the first few examples hold pressure. A manufacturer considering a production AM pressure component should instead decide at the development stage what constitutes the qualified product and process. That means defining operating conditions and credible failure modes, establishing material and process controls, determining the required inspection and test evidence, identifying the applicable regulatory route and deciding what changes would require revalidation. Where third-party conformity assessment is applicable, early discussion with the appropriate body is likely to be considerably more productive than presenting it with an already frozen design. There is a useful change of perspective here for the fluid power industry. The challenge is not really how to certify a 3Dprinted manifold. It is how to establish a repeatable and adequately documented manufacturing route that produces a component with known characteristics and supplies the evidence required for its particular application. Once additive manufacture reaches production, the digital model is only one part of that evidence. The feedstock, machine, process parameters, postprocessing, inspection and validation history matter as well. Treat those as part of the engineering from the outset and qualification becomes something that can be designed into an AM programme. Treat them as paperwork to be assembled after a successful print, and some of additive manufacturing’s most attractive fluid power applications may prove much harder to industrialise than they first appeared. Reader note: This article is provided for general information and discussion purposes only and should not be relied upon as engineering, regulatory, compliance or legal advice. Reasonable care has been taken to ensure that the information is accurate at the time of publication (September 2026), but regulations, standards and guidance may change and their application will depend on the particular equipment and circumstances. Readers should therefore verify current requirements from the relevant legislation, standards and authoritative sources and, where appropriate, obtain advice from suitably qualified specialists or the relevant conformity assessment body before making design, manufacturing, safety or compliance decisions.
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