Severe service ball valve applications are as varied as the process
industries that we service.   Stress to ball valves does not always
result from the traditional culprits of “ high velocity slurry flows “
or  “ high cycle frequency with aggressively abrasive fluids “.
We recently addressed a three way valve application involving two
distinctly different inlet fluids feeding to a common outlet. The valve
also required a neutral all off position so a 180 degree design was
required with a reliable 90 degree “ no flow “ position and a lockable
handle in all three positions.
Inlet “a” was dry superheated steam at 550 degrees f while inlet “b”
 was a gas at ambient temperature, nominal 70 degrees f. Further, the
valve required a design temperature capability to 800 degrees f and
class VI shutoff at 200 psig.
The elevated temperature dictated metal seat construction and
isolation of the two process fluids during both the off phase and the
operating “a” flow or “b” flow meant class VI shut off simultaneously on
both seats.
Our answer was Garmet-38 seats lap matched to a hard faced 316
stainless ball at a 1 micron finish. The seats were independently live
loaded against the ball valve using Inconel springs and all the seals were
graphoil for temperature tolerance.
Containment bolting used Belleville spring washers to maintain
compression loads during thermal cycling and to compensate for the
effects of the differential temperatures of the dissimilar process
fluids.
Our proprietary approach to seat geometry, seat loading and the
lubricating qualities of Garmet-38 resulted in valves with low operating
torques, smooth operation and class VI shutoff performance at both
inlet ports.
Think of us when the combination of design parameters and process need requires imaginative solutions that perform reliably.

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