Chardon, OH (PRWEB) June 28, 2012
Hands down, flexible graphite has proven its superiority to metal as a gasket material for high-pressure seals. It installs easier and seals more reliably, because it fully conforms to the valve surface. Since it doesn’t permanently stick or bond to the metal, it removes quickly and easily without any need for chisels, grinders or cutting torches — you just lift it out. Lifespan? It’s rugged enough to have satisfied U.S. Navy durability standards for seagoing nukes and 25+ year life cycle testing at a major US nuclear power station.
All of these factors make EGC Thermafoil Pressure Seals a preferred choice for OEM valve manufacturers. But for plant service professionals, there’s an issue that is certainly as important as functional superiority.
“‘How fast can you get it to me?’ That is the first question you’re going to hear from an aftermarket service guy” says Dick Dudman, an engineer and flexible graphite pioneer at EGC Enterprises. “He’s got a unit shut down, with management nipping at his heels to get back online, and he’s in a hurry. And back in 2003, when we first developed the die-molded EGC Thermafoil flexible graphite pressure seal, we didn’t have a very good answer. Average turnaround time was six weeks.”
In 2008, it got a lot better. EGC introduced a new seal called VSG that cut turnaround time to a few days. They found a way to eliminate the need for production tooling by creating a highly densified, EGC flexible graphite “pressure seal profile” and applying anti-extrusion stainless steel top and toe caps.
Dick Dudman again: “VSG delivers the same performance as our original molded seals — with delivery times a service manager can appreciate. Appreciate … but not love. The question was, could we find a way to do it even faster?” The most time-consuming part of VSG production is the top and toe caps. Their purpose is to contain the graphite under pressure, and maintain the integrity of the seal by preventing extrusion. Formed from flat stainless steel in a machine shop, they require precision equipment and a talented machinist.
EGC discovered that extrusion could be prevented using hard “edges” instead of full-faced caps. These containing edges, can be made of wire instead of machined caps. And the wire can be fashioned and applied in EGC’s shop on the same day. Result: a new seal called the VSG Pro, that can be completed the same day the order comes in, and then shipped via the quickest service available.
Now, service managers can get custom-designed flexible graphite seals faster than anyone could have predicted just a few years ago. With no production tooling, the price point is significantly lower, in fact the Pro is cost competitive with its metal counterpart.
How does the VSG Pro perform once in place?
“When the product is installed, there is no difference,” says Dudman. “There’s the same amount of graphite in the Pro as there is in the VSG and our original die-molded seals. All graphite seals resist valve pressure throughout the entire body of the seal. It’s not like a metal seal where all the energy is centered on the toe alone. In other words, graphite is under less stress in the cavity. The bottom line is that all three EGC flexible graphite seals are equally superior to metal seals.”
The VSG Pro does have different look, however. Because it’s not squeezed into a mold or compressed into metal caps, their must be some method of gluing or taping or shrink tubing to make sure all the components stay one unit when dropped in to the valve. The EGC solution is simple and economical. Dick Dudman again: “We wrap them in a few locations with cellophane tape. That way, it’s easy to just drop the seal into the valve. Then, when production is resumed and the valve gets hot, the tape just disappears.”
When all is said and done, the VSG Pro is a product that is superior to metal seals in applications such as power generation and other process plants where steam is involved. It requires no expensive tooling and can be completed in-house in only 48 hours, making it ideal for aftermarket rebuilders and maintenance personnel during an emergency or as plant outages occur. It is manufactured at a lower cost than it’s competitive metal seal eliminating barriers to entry. And, the VSG Pro reduces plant downtime because removal does not require a jackhammer and it’s incredibly easy to install.
Contact EGC Enterprises at 800.285.5835 or visit our site at http://www.egc-ent.com for additional information.
EGC is a recognized world leader in engineering and manufacturing of graphite products and composites for high temperature applications in fluid sealing or thermal systems management.