changes in production requirements. • Maintainability Even the best specified control valves will require maintenance over their lifetime to ensure optimum performance. Control valve design has a big impact on the ability to maintain a control valve and the cost associated with this.

Plant managers will already know that accurate temperature and pressure control maintains process efficiency, which makes control valves an invaluable part of any installation. However, understanding what to look for in a modern control valve can be overlooked. Spirax Sarco UK’s Darren Silverthorn, national controls and metering specialist, explores this critical issue


plant manager’s time is precious, so finding ways to maximise efficiency

and mitigate against the risk of downtime, extended maintenance and potential safety issues matters. Understanding what to look for in a control valve can help those very managers to help themselves – leaving them more time to focus on increasing productivity and boosting efficiency. Here are some areas of consideration

plant managers should make when sourcing an efficient control valve.

1. Specification Control valve specification is key to performance and longevity. The majority of control valve issues experienced in industry stem from incorrectly specified control valves. Having the right process conditions and an understanding of the process itself makes correct specification a reliable process. Incorrectly specifying a control valve


can lead to several challenges for plant managers such as, product quality issues, increased maintenance, control valve failure and production shutdown. With all of these challenges comes the possibility of increased safety risks.

2. Total Cost of Ownership When selecting a control valve it is important to consider the total cost of ownership (TCO) and not just the initial purchase price. Correct control valve specification will have an important part to play in a control valve’s TCO. Matching a control valve to the process can also bring efficiency gains in the form of costs, emissions and productivity.

Control valve design also has an impact on TCO, two areas to consider include: • Modularity Modular control valves are more adaptable and adjustable to mistakes made in the specification stage and/or

SPIRA-TROL control valve with TN2000 pneumatic actuator

3. Maintenance strategy Whether plant managers carry out their own control valve maintenance or use a third party, the design of a control valve will influence a plant manager’s strategy and budget. To stay one step-ahead of unexpected maintenance challenges, consider the following vital areas: • Materials Plant managers can help-themselves by asking whether the materials have been chosen with the process conditions in mind. For example, what grade of stainless steel has been chosen for the control valve internals, and will this stand up to the potential for corrosion and erosion? • Can it be maintained? On the surface of it a control valve may be advertised as maintainable, in reality however this is not always the case. For instance, control valves with screwed in seats are notoriously difficult to maintain with the seat sometimes being impossible to remove. Leaving managers with no option but to live with an underperforming control valve or take the unenviable route of buying a new one. • Ease of maintenance This key point can significantly impact process downtime and the quality of the control valve after it has been maintained. Plant managers may also take the decision to carry out maintenance in- house or use a third party, dependent on the ease of maintenance. The considered selection of a control

valve, coupled with a strong maintenance strategy, can make a real difference to product delivery, process uptime, compliance and efficiency. The suitability of the control valve to the process should always be considered right the way through the decision process, from design to installation to maintenance, in order to reap the benefits of the humble, but invaluable, process control valve.

Spirax Sarco


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