How Metrol Maintains High Standards in Gas Spring Manufacturing

Gas Spring design and manufacture, The pressure equipment directive 2014/68/EU, CE and UK CA marking

Gas springs are pressure vessels with a basic construction of a cylindrical sealed body and a piston rod that can be pushed into the body, compressing the gas and providing a resistant force to push the rod back to its fully extended position. Gas springs are charged with high-pressure nitrogen. Nitrogen is used as it is inert, cost-effective and readily available.

Gas springs are stored energy devices. For this reason, they must be handled and used in a safe manner and to the manufacturer's guidelines. Metrol provides a combination of gas spring user instructions and gas spring safety training courses, so users of our products can be assured they have all the knowledge and best practices to safely handle and use gas springs.

Metrol gas springs, designed and manufactured in the UK

Metrol is the UK's largest gas spring manufacturer, with a range of gas springs for the metal stamping industry and SAS heavy-duty gas springs for industrial applications. All of our gas springs are fully designed and manufactured at our facility in Northampton, UK.

We supply the UK market directly and export globally through our distribution network in Asia, Europe, N.America and Africa.

What is the PED 2014/68/EU?

The PED sets out a standard of conformity for the design and manufacture of pressure vessels. When applied to a gas spring, several essential safety requirements (ESRs) must be met. All gas springs with a volume over 1L must conform to this standard and be marked accordingly before being placed on the market in the EU and the UK.

CE and UK CA marking, does this apply to all gas springs?

No, and this can cause confusion. The criteria are set out in the PED, but basically translates to gas springs above 1L in volume must be permanently marked with a CE or UK CA mark, whilst gas springs smaller than 1L should not carry a CE or UK CA mark. So what does this mean? Gas springs that do not carry a CE / UK CA mark are designed and manufactured to sound engineering practice; gas springs marked with a CE / UKCA mark are designed and manufactured to conform with the requirements of the PED.

Brexit and CE marking

Brexit resulted in the UK having a desire to have its own quality approval, with the CE mark to be replaced by a UK specific UK CA mark. Currently, the UK is in a transition period, and the CE mark is still acceptable until 1st January 2023, after which all gas springs for the UK market and that must conform to the PED must now have a UK CA mark. This means that foreign manufacturers must use a notified body to assess the company and its products to the UK CA standard and vice versa for UK companies wanting to apply a CE mark for export to the EU. So, for example, Metrol is approved to apply a CE or a UK CA mark, meaning our customers will receive approved products wherever they are in the world.

What is the difference in the design and manufacturing process between sound engineering practice and the PED?

The PED is a more rigorous set of standards compared to sound engineering practise (SEP). SEP does not list specific requirements as the PED does, rather a rule that products should be safe and delivered with a user manual. The PED sets out a number of essential safety requirements that must be met before the CE / UK CA mark can be applied. The ESRs are complex, but a simplification of the most important requirements:

• Product type testing, including fatigues testing to 2 million cycles
• Use of materials that must have certain properties
• Steel sourced from approved sources within the UK or EU
• Full traceability of components back to the original 3.1 mill certificate
• Design standards that meet critical safety factors
• Non-destructive testing, including pressure proof testing of every spring

Gas spring manufacturing standards at Metrol.

By conforming to the PED standards, Metrol gas springs, along with all our other products, such as our fixed force gas struts, will meet the strictest safety standards in the industry.

Metrol uses the PED standard as a benchmark for designing and manufacturing all our gas springs and adjustable gas struts. Using this standard over the less rigorous sound engineering practice, we ensure that Metrol meets the highest quality and safety standards for this type of product.

In addition, our ISO9001:2015 quality management system complements our work with the PED standards to form a fully comprehensive design and manufacturing standard. Every material process and operation is recorded and fully traceable in a fully digitised system. Our commitment to continuous improvement provides a progressive platform for sustainable growth.