Expanding Gate Valve - Energy Products Company

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Valve World Americas had the opportunity to speak with Dustin Thompson, Engineering Supervisor at Franklin Valve LP, about expanding gate valveexpanding gate valves, and dual expanding plug valves, their intricacies, benefits and how they differ from other types of valves.

What is an Expanding Gate Valve?

An expanding gate valve has an internal closure mechanism consisting of multiple pieces that expand in line with the bore of the valve, creating a mechanically energized compression seal. “An expanding gate uses thrust generated by a threaded stem and drive, which pushes the gate mechanism downward, where it then expands horizontally so the seats compress in a horizontal motion,” said Thompson. “This means there is no vertical sliding or abrasion between the seating surfaces.”

An expanding gate valve would be beneficial for applications where isolation is extremely critical. “Examples include metering applications, tank farms, fueling systems and, multi product manifolds,” said Thompson. “If I have diesel on one side, and jet fuel on another, and a valve has any allowable leak rate, it will contaminate the jet fuel with diesel.” In this case, an expanding gate valve with positive double isolation-and-bleed (DIB) isolation, is useful to maintain critical isolation. Expanding plug valves can also be used in similar applications as expanding gate valves, “or whenever you need complete isolation for critical equipment or between two different fluids.”

A dual expanding plug valve has two motions to its operating cycle: a quarter turn and linear motion. “Similar to the gate valve, the internals consist of a taper plug, and two independent slip seals,” said Thompson. “Cycling from open to closed, the valve will quarter turn followed by the linear motion, which expands the slips. As that plug traverses downward, it horizontally expands the slips into the seal.”

Comparing the two valves, the best option would depend on the application, which is a better face-to-face match, and size requirements. “In smaller sizes, an expanding plug valve is more cost effective than the gate valve, but in a larger size, the gate valve may be expensive due to weight and manufacturing technique,” said Thompson. “The face-to-face dimension of a large gate valve can be much smaller than that of a large plug valve, but they are both double block-and-bleed DBB and DIB capable.” With a DBB valve, there are usually two unidirectional self-relieving seats, in contrast, a DIB valve utilizes one or two bidirectional seats.

What Sets Them Apart?