Alternative Sealing Technology Solves Shaft Leakage Problems

• Delivers Productivity Improvements
• And Savings in Plant and Maintenance Expense.

Shaft seal leakage in pumps, valves and agitators can be the source of other more serious plant and production problems. Often they affect housekeeping, employee health and safety, environmental control, production yields, and from time to time the cause of costly unplanned plant downtime.The use of braided packing and mechanical seals have been around a long time. For the most part, these serve their purpose well. However, for many applications, other simpler, more cost effective, more energy efficient and more versatile technologies and devices have emerged and they are providing effective solutions to these everyday plant leakage problems.Johns Manville's Shenandoah Valley Plant in Edinburg, Virginia is a major producer of home building material products. Among other plant assets, it uses some 35 Galigher 4x6 pumps handling a variety of plant liquids under a range of process conditions. Many of these streams are abrasive slurries. There are also 7 side-entry Lightning agitators installed on 40,000-gal. reservoirs. All of the pumps and 5 of the agitators use conventional braided packing to control shaft leakage, the other 2 agitators have been retrofitted with mechanical seals. All of these installations have suffered frequent shaft leakage problems over the years. The process conditions as well as the presence of the abrasive particulates also caused premature seal failures, expensive rebuilds of pumps, shafts and sleeves, replacements of key component sealing parts and, most of all, expensive process downtime. The use of conventional packing and mechanical seals also required a steady flow of seal water to lubricate and cool the shaft and stuffing box in order to minimize wear and tear on key component parts. "On average, we used about 10 GPH of seal water per piece of machinery when we were running, " commented Scott Huston, the Plant Engineer. "And, because our plant has no discharge stream, we had to provide holding capacity for the spent water for reuse in process. Frequently, this caused storage problems and eventually we had to find dryer capacity to get rid of the wastewater. I imagine that for those plants with the ability to treat wastewater and discharge, they would still have to deal with wastewater treatment and the cost," Scott Huston added.

Kem-A-Trix^TM, the manufacturer of the IFS^TM Injectable Fluid Seal system, suggested the use of its IFS^TM 4001. The IFS^TM system uses a blend of synthetic colloidal fibers, impregnated with a blend of synthetic lubricants. The system is designed to be stable under elevated temperatures and pressures. When installed with anti-extrusion gaskets (referred to as "restrictors"), the product forms a lubricated seal within the stuffing box and hugs the shaft without added compression. This design assures an effective seal with the lowest running temperature and stuffing box pressure, without the use of cooling water. After startup and if a leak develops, one simply inject a small added amount of the IFS^TM material to restore the seal, all done on-line and without having to interrupt production. "We have installed the IFS^TM system on 8 pumps and 4 agitators for nearly a year." Scott Huston says. "It appears to handle the abrasive slurries well and I believe we are very much in control of shaft leakage now. The fact that we no longer require seal water has been a major benefit. IFS^TM has generally helped us improve the process. IFS^TM installs easily, and with the injector loader, we are able to maintain the shaft seal while the equipment is running. I expect that over time we will be converting more and more to the IFS^TM product."

copyright July- August 2001 issue Maintenance Technology