|Graphite-encapsulated , stainless-steel gasket design solves many problems that are inherent to sealing applications on stationary equipment.|
As the manufacturing and process industries struggle to trim costs, there is an ever-shrinking margin for inefficient or stopgap maintenance techniques. Successful managers are raising their maintenance standards in order to extend uptime and avoid maintenance crises that choke production.
Gaskets are a good example of a relatively low-cost item where improved standards can prevent repetitive maintenance problems. Chronic leaks and blowouts of heat-exchanger gaskets, for example, can bring an entire process down. A definite need for improved gasket protection becomes apparent when downtime per failure is considered. This can be particularly true of applications where gaskets are viewed as industry-standard, no-brainers — yet where leaks, unsatisfactory service life, and time-consuming labor are endured as acceptable evils that are inherent to “difficult” sealing applications.
“Gaskets have been failing prematurely forever,” says Gary McCoy, business development manager for A.W. Chesterton (www.chesterton.com), a manufacturer of industrial fluid sealing solutions. “In many applications they are subjected to high pressures, thermal cycling, vibration, and other stressful conditions. With hundreds of gasket installations throughout a plant, many premature failures cause expensive process disruptions or other problems. Yet, in too many cases, the failed gaskets are simply replaced with the same model.”
McCoy is a proponent of a new generation of gasket technology, a high-tech, flexible, graphite-encapsulated stainless steel design that solves many problems that are inherent to gasket applications on stationary equipment.
“One of the major advantages of a graphite stainless-steel gasket is its ability to go through temperature cycles,” McCoy explains. “This is a very thin (approx. 1/32”), convoluted stainless-steel gasket with a graphite sealing medium on both sides that you compress to the thickness of the gasket metal. We now use this technology in many applications where spiral-wound gaskets were traditionally used.”
Chesterton, a supplier of mechanical seals and packing products to the petrochemical, pulp & paper, shipping, and other industries, frequently recommends the graphite-encapsulated, stainless-steel gasket marketed under the SteelTrap brand. These gaskets are manufactured by Sealing Corporation (Selco, www.selcoseal.com).
“For years and years we used the standard gaskets on our main steam drums and our lower water wall headers,” says Stuart Bussman at TransAlta Power (www.transalta.com). “After six cycles, we had to replace them. There are 20 gaskets on each unit, so it was an expensive and time-consuming proposition.” After successfully testing a graphite-stainless manway gasket in a boiler, Bussman says he decided to try SteelTrap gaskets for the main drums. “We”re very pleased with the performance of these gaskets. We”ve had no cycling problems and the overall cost savings has been very substantial.”
“The cost of the gasket is not the question,” says Vance St. Jean, sales manager for Chesterton in Houston, Texas. “Your costs aren”t really dependent on the sealing device. Your costs are associated with changing it out — the labor, the downtime, the process disruptions, and the other problems. Once I explained that to one of our refinery customers, they agreed with me. Doing it right might be worth thousands of dollars, or it might be worth millions of dollars. It depends on the situation.”
“The graphite-stainless gasket is also much more forgiving in terms of poor bolting procedures and imperfect conditions of flange plate surfaces,” McCoy adds. “Unlike other gaskets that creep or cold-flow under load, and you lose gasket volume, the SteelTrap eliminates that problem — takes it to zero. Because of the convolutions of the metal, the sealing material is trapped on all sides by metal. That”s where the gasket got its name.”