Even as the oil and gas industry continues to navigate the volatile market that has seen fluctuating oil prices, operators, service providers and suppliers alike are adapting and evolving their businesses through new service models and delivering innovative products that improve operational efficiencies and increase uptime.

One of those key products is the control valve, which is typically used to regulate flow, temperature, pressure and fluid level across a variety of applications including production, refining and processing, gas storage and transport, and liquid transport. According to the World Control Valves Market—Opportunities and Forecasts, 2014- 2022 report by Allied Market Research, there will be a significant growth in the global control valve market over the next five years, with the market expected to reach $13.6 million by 2022 at a compound annual growth rate of 7.6% from 2016 to 2022. The oil and gas and power market is leading the way in terms of demand for control valves, with North America being the largest regional market.

The oil and gas and power market is leading the way in terms of demand for control valves, with North America being the largest regional market.

Despite the optimistic outlook, the current challenges of this downturn with declines in capex and opex budgets oftentime shine a light on problematic applications where current control valve technologies deliver less than adequate performance, prompting operators to search for a more flexible, reliable and cost-effective solution. SPX FLOW’s general service control valves, for example, are cost-effective options for delivering reliable and versatile performance for nonsevere flow control of most liquids, steam and gases.

For more severe and critical-duty services, severe-duty control valves are designed for compressor antisurge/ recycle, pump recirculation, vent-to-flare and wellhead choke applications that often experience flashing, cavitating and sonic flow conditions or applications that generate high levels of noise and vibration levels in a general service valve.

Control valve trim

A key component of any control valve is the trim, which controls the process application envelope, even under extremely high-pressure drops and flow conditions as well as preventing valve damage by eliminating a variety of conditions such as flashing, cavitation, wire drawing, erosion, noise, vibration and instability.

The RAVEN trim developed by Copes- Vulcan, an SPX FLOW brand, enables the control valve system to reduce and maintain flow velocities at low levels, resulting in quiet, noncavitating and nonerosive operation. These results stem from the unique enhanced design that takes the well-known labyrinth stacked-disk velocity- control technology and introduces two new features: reduction in trim outlet noise and higher tolerance to the effects of particulate blockage.

The inherent capabilities of the labyrinth stacked-disk technology allow easy customization of the trim to match the process condition envelopes that would otherwise require multiple valves or that might otherwise cause irreparable damage to the plug, trim or seat of stacked-disk trim control valve design of other valve trim types.

Resistance to particulate blockage effects

In conventional labyrinth stack designs, particulate blockages in the stack jeopardize all or a portion of the system controllability, and in the case of a partial blockage, excessive noise also can be generated. To resolve these problems, the RAVEN trim combines an expanding tortuous passage design with multiple entry points to individual flow passages, significantly decreasing the impact or chance of particle blockages. The trim also incorporates relief points, which under normal operation have virtually no flow through them. In the event of a blockage, the relief points (inlet and outlet ports) minimize the impact on the controllability and capacity and ensure the integrity of the system.

Noise reduction

The labyrinth-type trim has been widely accepted over the past two decades as the best solution for highvelocity flows resulting in high noise and vibration. Their wide acceptance is based on the concept of reducing mass flow and strict control of the velocity of the trim’s medium. SPX FLOW developed the next-generation trim when it found that by splitting the outlet flow of each labyrinth path into three or more small mass flows rather than the one large flow, noise could be reduced by 3 dBA over that produced in a typical labyrinth arrangement.

The combined effect of numerous split flow channels— each with many sharp turns and a continually expanding flow path—more efficiently removes kinetic energy from the fluid by gradually lowering its pressure. As a result, abrupt velocity increases, which are the source of noise, are avoided.

Improved velocity control

The RAVEN trim’s design has numerous split flow channels, each with sharp turns and expanding flow paths that remove kinetic energy from the fluid and gradually lower its pressure. By limiting fluid velocities inside the valve, the trim precludes problems typically associated with high velocity such as erosion, noise, vibration and poor control. An additional benefit occurs in liquid flow by eliminating cavitation and the damage it can do to a valve, its trim and the downstream piping.

The actual gaseous flow through RAVEN trim shows the visible attachment phenomenon wherein the flowstream clings to each obstruction in its path, effectively taking the line of least resistance. In addition, despite the multiple relief points in the flow path, the fluid does not recombine within the RAVEN trim. Instead, the flowstreams remain virtually separate from each other, ensuring optimal velocity control. High velocity is a root cause of noise and vibration that can cause seal failure, instrumentation problems and cracking of valve components. Because the RAVEN trim has high velocity control capabilities, vibrations are eliminated, ensuring longer service life and reliability to the valve and nearby piping and machinery.

Quick-change design

Customers expect a long service life for severe service control valves. However, system upsets do occur, which might require an unplanned control valve repair. Fortunately, the RAVEN trim employs a quick-change design that enables it to be easily removed and replaced from existing valves without having to remove the valve from the operating pipeline. In fact, the trim can be quickly customized to fit existing valves manufactured by other suppliers. These retrofit options can be pre-engineered and included in maintenance budgets as a spare trim component, which results in a significantly lower cost option compared to replacing the entire valve, making it a cost-effective option in an environment driven by low capital and repair expenditures. In addition, operators experience a shorter installation time as most trim refits can be completed onsite within a one-day time frame.

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