Elastomer Valves Aid in Groundwater Remediation Project

The Yorktown Naval Station, Yorktown, VA, maintains several underground refueling tanks that have been obsolete for a number of years. The tanks contain thick, barely refined oil that leaks into the ground, contaminating groundwater flowing into the Chesapeake Bay.

A variety of elastomer valves were used in the Yorktown project, including control and manual pinch valves, and Tideflex? inline check valves.

The station called on OHM Remediation, Trent, N.J., for the design and construction of a groundwater remediation plant that would clean the surrounding soil and improve the quality of the site's runoff. The challenge lay in the abrasiveness of the thick slurry, which is only refined to one level above crude oil.

To address that challenge, OHM Remediation standardized on Red Valve's elastomer products. The installation list consisted of control and manual pinch valves, Tideflex® inline check valves, Redflex® expansion joints and pressure sensors.

The Red Valve pinch valve features an elastomer sleeve that isolates the valve body from the process material. This eliminates the need for expensive metal alloys and protects the valve body from wear. The elastomer also resists abrasion and corrosion.

On the inlet and outlet sides of the pumps, manual pinch valves provide on/off service. When fully open, the pinch valves are full-ported and function as a pipe extension, causing no interruption in the flow. When pinched closed, the elastomer sleeve is flexible enough to seal around any entrapped solids that might be present, such as sand and grit. There are no crevices in the tubular sleeve to collect solids, so closure is uninhibited, even after long periods of inactivity.

Electrically actuated control pinch valves are installed at the Yorktown plant for throttling service. For applications that require continuous throttling, Red Valve provides its patented cone-shaped sleeve as standard. Unlike a standard pinch sleeve, which is naturally full ported, the open area of a cone-shaped sleeve is inherently reduced to achieve a specified flow rate without actuation. A standard sleeve is throttled through a tight midstream restriction that creates an elliptical open area, whereas a cone-shaped sleeve has a rounded open area that can allow larger solids to pass.

For backflow prevention, an inline Tideflex® check valve is installed on the vertical pipe. The inline check valve contains an elastomer check sleeve with a contoured shape that is similar to a duck's bill. During normal plant operation, the sleeve remains open, allowing forward flow. In the event of a plant shutdown, however, fluid flows downward through the pipe and exerts backpressure on the sleeve's opening, sealing it shut. Like the pinch valve, the inline check valve's elastomer sleeve isolates the body from the process fluid.

Redflex® expansion joints are installed throughout the Yorktown plant to absorb vibration. The all-elastomer construction of the expansion joints resists abrasion and corrosion and provides flexibility to accommodate pipe movement and shifting.

Finally, several Red Valve pressure sensors are in operation at the Yorktown plant. The pressure sensors operate with a 360-degree elastomer sensing ring that completely contains the process fluid. The ring protects the instrumentation from clogging and damage, ensuring sensing accuracy.