A natural gas plant in Texas had six highly specialized mainstream control valves that exhibited steam leaks through the pressure seal cavity. The leaking increased with time, and no matter what the team did in terms of resurfacing the cavity or changing the metal pressures seals, the steam kept leaking and the valves made an awful, noisy ruckus.
The metal pressure seals within the valves had been leaking so badly that there was a giant hissing noise in that area of the plant. A metal replacement would have required a massive amount of machining to bring the bonnet cavity bac, so the plant called EGC instead.
“Flexible graphite pressure seals were the ideal solution, but the engineering was a challenge,” explains Rob Garlock, Fluid Sealing Engineering Specialist with EGC. “There was only a .320-inch bonnet neck height – normally the rebuild teams have 1/2 to 2 inches – but this neck was extremely short. This time, the installed length of the seal was absolutely critical.”
Paying strict attention to the minimum and maximum conditions, EGC was able to engineer a singular design that would work for all 6 valves. “Had they used a metal seal, they would have had to make a specific seal for each application,” said Garlock. “We saved them a substantial amount of money doing it our way.”
The characteristics of flexible graphite to conform and compress were the key, even when out-of-round conditions persist. When high-density graphite is placed within the bonnet cavity and the bolts are tightened, it draws the bonnet up. Graphite literally can take the shape of the seal area in a way that metal seals cannot. It also works in oversize, steam cut and pitted bonnet cavities without the need for welding, grinding or refinishing.
In an email sent to Thom Jessup, EGC’s Sales Manager for Industrial Fluid Sealing Products, the plant’s team said: “Thanks for being the brain-child for Graphite seals. We took the unit 1 for a test drive today, and it was eerily quiet! Without the main steam blowing all over the place, it sounds like a different machine. Another huge thanks to the rest of the crew for setting us up with this fine product.”
Aside from being quiet, the VSG Pro is resilient, so it seals every time while rebounding after every pressure cycle. It won’t fuse to valve components, and after use, lifts right out of the valve. In time studies for valve maintenance, you can save nearly 75% installing graphite over metal. Every VSG Pro is custom engineered, manufactured and has a scheduled lead time of just 48 hours. Same day if necessary! Visit www.egcgraphite.com or www.outageseason.com for more information.
EGC is here to help you solve your challenges. Call 440.285.5835 today and put an end to leaky valves!
EGC is a recognized world leader in the engineering and manufacturing of graphite composites for high-temperature applications in sealing or thermal systems management. The EGC website can be accessed at https://egcgraphite.com/.