Typically, a power plant shuts down a couple of times a year to allow safety and maintenance items to be performed. In the case of Georgia Power, a Southern Power facility located in Carrollton, 25 bonnet seals had to be replaced and Industrial Valve, a mobile Alabama company, was given the contract. As is typical in all power plants, Industrial Valve had only nine days to complete the operation.
Nine days may sound like a lot but it’s not. Southern Power is a gas-fired, combined-cycle steam plant and the valves are everywhere, sometimes hovering three stories high to being located underground. In manual repair, they range from 900 pound pressure seal valves to 4,500, and in sizes, as small as a 4-inch diameter seal to as big as 24 inches.
Fortunately, each valve came with an EGC enterprises VSG pressure seal making the replacement go a lot faster. “We called EGC and pre-ordered the VSG Pro pressure seal,” said Rusty Franklin, Sales Manager for Industrial Valve. “Normally, we’d have to work round the clock to change that many pressure seals in nine days. But the VSG Pro makes the installation a whole lot simpler.”
The VSG Pro, made of high-density graphite, provides a mechanism for anti-extrusion and requires no production tooling. The VSG Pro is manufactured through an innovative process whereby time-to-build is greatly reduced offering a standard lead time of 48 hours.
“It’s the forgiveness of the seal that won me over,” says Franklin. When dealing with a metal seal, “we spent hours machining pressure seal stuffing boxes and it was very time consuming. With the VSG, they come premade and if the pressure seal cavity doesn’t look good, we take scotch-brite and clean it. It handles nearly any imperfection.”
Bonnet seals form a barrier to prevent the venting of steam from the valve. Typically, a silver plated metal seal is used. The metal seal installs easily but during its operation it can actually become an integral part of the valve making it extremely difficult to remove, requiring re-machining.
Says Franklin, if Industrial Valve is replacing a metal seal, “it takes four hours to make a pressure seal doughnut on a 16-inch valve and another four hours to machine it and that’s a lot of time to spend when you only have nine days to do the job.” According to Franklin, the VSG Pro installs in six hours and that’s everything from bonnet removal to replacement to valve reassembly.
The VSG Pro is unsurpassed in its ability to seal and is competitive in cost with its metal counterpart. Its ease of removal means you’ll never have to re-machine the valve again. Says Franklin, “the VSG Pro has made a believer out of me and I can see how they would make the metal seal obsolete.”
Corporate Profile
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 http://www.egcflexiblegraphitesolutions.com, or visit our WooEB Hub at wooeb.com/egcenterpises
