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Advances in high precision valve design and manufacture

Published: 28 November 2012 - Michelle Lea

ARI-Armaturen has been designing and manufacturing specialist valves used for isolating, securing, controlling and steam trapping across a wide range of industrial processes for more than 50 years. The company’s pre-eminence in the demanding field of process control has been achieved through an ongoing commitment to research and development, providing new generations of equipment to meet the complex demands of industry today

ARI’s modern development methods, including its own in-house state-of-the-art experimental laboratories and testing facilities, together with their high precision manufacturing techniques, ensure optimum performance from every ARI product. Take the new ARI ZETRIX® triple offset process valve, for example.  ZETRIX unites the benefits of a metal-seated process valve with all the advantages of a butterfly design. It’s permanently leakproof, durable and versatile and guarantees isolation and control in harsh industrial environments such as those found in oil and gas processing, refineries, petrochemicals and power stations.

The ZETRIX design was developed and optimised using the very latest generation of tools and modern manufacturing technologies:

Finite Element Analysis (FEA)

Minimal stress on all features of a process valve improves valve longevity and safety.  ARI engineers use FEA – a numerical calculation technique used to simulate stresses – to analyse stresses and their distribution over the valve disc. This testing and simulation method resulted in development of a process valve of the required strength at pressure load levels up to PN40 in combination with a compact, low weight design and flow-friendly shape.

State-of-the-Art Flow Simulations

The twofold objective of uniform flow and high flow capacity was realised with the aid of special flow software. The software simulations enabled the flow velocity, flow direction and pressure distribution to be visualised. As a result of the optimised ZETRIX geometry, turbulences are reduced to a minimum and pressure loss prevented.

Contact Angle Calculation and Characteristic Measurements

Sizing software allowed the contact angle at the perimeter of the valve seat to be visualised allowing optimisation of the peripheral closing angle to ensure that the valve opens and closes without sticking and without friction. The triple offset principle guarantees a permanently tight seal conforming to leakage rate A in accordance with DIN EN 12266-1.

The flow values at different opening angles were measured in the testing laboratory and the resulting curves were used to determine the control characteristic of the ZETRIX valve.

Last but not least, the new valve was subjected to the ‘acid test’. In many applications there is an increased fire hazard. In the event of a fire, the valve must continue to meet internal and external leak-tightness requirements for a defined period of time if exposed to direct flame impingement. This ability was demonstrated in a firesafe test according to ISO 10497.

High Precision Manufacturing

ARI products are manufactured in Germany to rigorous quality criteria using high performance machining centres, automated assembly cells and programmable assembly robots.

The valve bodies of the ZETRIX process valve are manufactured on fully automatic CNC controlled machining centres. All CNC programmes are developed by ARI’s in-house programmers from CAD data which is transferred to the control online. The sealing surface of the ZETRIX valve is coated with stellite by a fully automatic welding robot with an integrated measuring system.  The three-dimensional measuring system shown in Fig C allows the process valves to be compared with 3D data which is subsequently evaluated and saved on a PC. The measurements are carried out directly in the machine to ensure reliable production processes.

Every ZETRIX process valve is leak-tested according to DIN EN 12266. The test pressures and times are stored on a computer aided test bed. Special tests can also be performed at the customer’s request.

The continuous monitoring throughout all phases of the design and production processes of all ARI-Armaturen products is documented in some twenty system approvals and ensures delivery of high quality products with a worldwide reputation for safety, reliability and efficiency.

ARI-Armaturen

T: 01684 275752                   

E: ndavies@ari-armaturen.com

www.ari-armaturen.com

Industry Connections: Ari-Armaturen UK Ltd


 
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