Everything wears out over time. If the fluid process conditions begin to degrade valve performance after commissioning, the service is severe. The conditions can be adverse temperature, aggressive fluids or high differential pressure. Valve design must address severe service conditions for service life to be acceptable to the customer. The longer the life, the better the severe service control valve.

A clear definition of service conditions. Fluid mixtures and mixed phase flow are difficult to control due to potential for phase change in the valve trim. Unclear Max/Normal/Min conditions can lead to sizing error causing control range to be too high or low. Duty cycle and expected service life, often unclear, can lead to disappointment.

Loss of control indicates a need for maintenance. When trim erosion reduces restriction the control range must shift lower. As the low end of the control range approaches zero, the minimum restriction required is too low for the eroded trim to provide. An internal mechanical failure, commonly due to vibration-induced cumulated stress cycles of the trim will immediately cause failure, but can be avoided by proper severe service design.

Everything. Resistance to material degradation is always a factor, and conditions dictate the type of erosion to expect. Chemical-induced erosion requires the flow path and elastomer seals to be compatible with the chemical. Erosive forces from vaporized fluid impingement require localized areas of very hard material. No material exists that can successfully resist cavitation.

If bubbles in the fluid formed due to sudden velocity increase collapse in the valve, adjacent surfaces erode. Valve design influences the location of the damage. The trim in a standard globe control valve will erode immediately past the restriction location if pressure recovers before fluid exits the trim. This will reduce and shift the control range. A multiple orifice disc trim can not only suffer cavitation damage, but will direct the cavitating fluid off axis to impinge on the valve liner or body to potentially cut through the body to the environment.

Trim component surfaces contacted by high velocity fluid must be resistant to erosion. The affected areas only need protection; thus, hard surfacing processes are applied. Cobalt and tungsten are the most common alloying elements in iron alloys to improve erosion resistance. These alloys can be weld inlaid to the base material in the areas where fluid impact is expected.

Cavitation occurs when the local pressure of a fluid drops below its vapor pressure, generating bubbles that implode violently upon contact with metal surfaces.

The Atlas valve avoids this phenomenon by maintaining low static pressure throughout the restriction zone via its annular flow path, then allowing gradual pressure recovery without fluid impingement on the walls.

Two basic designs are common in anti-cavitation trim. Both rely on extending the distance of the restriction. A labyrinth-type trim forces fluid through a maze of channels. A perforated caged trim includes multiple small holes whose diameter is much less than the length of the holes. Flow control is achieved by exposing different amounts of channels or holes. While effective in preventing cavitation, control range is limited and trim can still be eroded or clogged by contaminates in the fluid.

The Atlas Severe Service Control Valve (SSCV) is a patented high-capacity, high-recovery control valve designed to withstand continuous choked-flow conditions. Unlike conventional globe valves, the Atlas uses an axisymmetric flow path that eliminates cavitation, reduces noise below 60 dB, and delivers up to 700:1 control range.

Conventional globe valves use a tortuous flow path that creates localized low-pressure zones, leading to cavitation, noise, and rapid erosion. The Atlas SSCV's 360-degree uniform pressure dissipation design eliminates these failure modes entirely. The result: valve life measured in years instead of months, with near-zero maintenance.

EP (Equal Percentage) characterization offers progressive control gain suited to applications requiring stable regulation across a wide flow range. ERL (Extended Range Linear) characterization is designed for applications requiring an extended linear relationship between valve position and flow rate, with a rangeability of up to 40:1 depending on the model.

Atlas can deliver a control range up to 700:1 thanks to its multi-turn helical bevel gear-drive mechanism. This allows precise throttling control across the entire operating range, far exceeding the typical 50:1 of standard globe valves.

Standard body materials include WCB, WCC, LCC, and CF8M (316SS). High-alloy options include Duplex 2205, Super Duplex 2507, Alloy 20, Hastelloy C-276, and Inconel 625. Trim materials include Stellite 6, Tungsten Carbide, and ceramic coatings. We select materials based on your specific process chemistry and conditions.

Yes. This is one of the specific applications identified by VSI LLC. The Ultralube™ coating, erosion-resistant trim materials, and flow path geometry make the Atlas particularly well-suited to these demanding conditions.

API 6A and ASME B16.34 for materials and construction. Triple-sealed for process fluids up to 450°F.

The Atlas SSCV is available from ANSI 150 through ANSI 2500, with a maximum pressure rating of 6,000 PSI. Custom pressure ratings are available on request for special applications.

Standard sizes range from 1" through 24". Larger sizes can be engineered for specific project requirements. Contact our engineering team for sizing assistance.

In most cases, yes. The Atlas SSCV is designed with standard face-to-face dimensions and flange connections, making it a direct replacement for existing globe valves without piping modifications. Our engineers will confirm fit during the sizing process.

The Atlas SSCV is designed for near-zero maintenance. Because cavitation is eliminated, there is no trim erosion, no seat damage, and no need for the frequent rebuilds that plague conventional valves. Typical maintenance intervals are 5–10+ years depending on service conditions.

Field data shows Atlas valves running 3–10+ years in continuous severe service with no trim replacement — compared to 3–12 months for conventional globe valves in the same applications.

Phone: 918-645-7170
Email: info@vsillc.com
Address: 1611 S Utica #338, Tulsa, OK 74104