Disc Stack Insert Repair
One of the special services that Valve Trim Industries offers is disc stack cage repair. This state-of-the-art precision repair process demonstrates VTI’s precision craftsmanship and exceptional capabilities. A multi-disc stack with damage impeding the flow path would normally be thrown away and the plant would be forced to purchase a new one from the OEM. VTI has developed a process to fix this damage and recondition the disc stack to like new condition with no change to the original flow characteristics. This service is offered at a fraction of the cost of a new disc stack and typically can save thousands of dollars per disc stack and millions over the course of operation.
Plug Strainer Upgrade for Mitigation of Sticking Problems Due to Magnetite
It is a common occurrence for Hot Reheat Turbine Bypass and High-Pressure Turbine Bypass valves to experience significant build-up of magnetite (iron-oxide) within the bonnet area of the valve. In these under-the-plug flow applications, the magnetite particles, floating in the steam, work themselves up through the balance holes of the valve plug, and gradually collect between the plug and the bonnet spacer or guide bushing of the valve. The build-up of magnetite causes the valve plug to stick, eventually preventing the valve from opening at all. This build-up occurs rapidly, requiring frequent interventions to clean the plug and internals. This magnetite problem can be alleviated by the installation of a plug strainer in the existing plugs, and by modifying the guide bushing by increasing the tolerance on the ID of the guide bushing, thus creating a slightly larger gap between the plug and bushing. These strainers will greatly extend the operating period between sticking problems. The strainers trap the magnetite within the plug, preventing it from traveling up through the balance holes, and depositing it into the gap between the plug and the guide bushing. Additionally, a slope or funnel would be machined out on top of the plug, causing any magnetite which does make it through the strainer to slide back into the balance holes.
Valve Trim Industries was asked by a client to help solve a continual problem of magnetite build up in two CCI Drag Valves. The valve applications were for an HRH Bypass to condenser (18” x 22” Angle Valve) and an HP Steam Turbine Bypass (8” x 8” Angle Valve).
VTI’s solution was to modify the plugs to install a magnetite strainer in the plugs. In addition, the gap between the plug and guide bush is modified. With this solution all magnetite is collected inside the plug, minimizing sealing issues, and can be removed during regular maintenance.
Custom Valve Engineered and Manufactured to Replace Obsolete “Sulzer B-E”
One of the biggest problems plants have today is chasing down parts for the many OEMs of various valves. There are issues with long delivery dates, high prices and less than stellar quality. This can be due to the fact that most OEM parts are not manufactured in the USA anymore, but overseas. On top of all that, then there are the obsolescence issues with older valve OEMs that do not stock parts any more or sometimes are no longer in business. That’s where Valve Trim Industries can come to the rescue!
We specialize in the ability to reverse-engineer your new or used spares, create the CADs and CNC programming to become your direct supplier for parts. And if you tell us that you have multiple of the same valve operating in your plant, but only need one set for now, we will manufacture the extra trim sets and stock them for you until you are ready to purchase the next set. This saves you money on inventory fees, saves you the stress of needing parts expedited and saves you the concern of having your parts manufactured outside the United States. We essentially become the OEM and your primary contact for that valve trim. And yes, we will offer this service for all of your critical valves, regardless of the manufacturer.
An example of VTI performing this service was when a 2500 MW power plant that had multiple obsolete Sulzer 6”-2500# class valves installed for boiler steam extraction contacted us for help. With our engineering designer, we visited the plant, created specs based on data from the original valves, then custom designed and manufactured entirely new valves to replace their existing ones. The trim was updated with our custom multi-stage disk-stack that could be disassembled for maintenance. We manufactured the bodies from solid ASTM A-182 F-22 alloy steel – instead of casting like most OEMs. And we upgraded all critical internal trim with Inconel and Stellite-6 overlay. The result was VTI providing power-house, made-in America, bespoke valves and becoming this plant’s new valve OEM. This was a great project we are proud of with a very happy customer.
