Article: Alternative control valve repair solution yields savings

Emerson recently published an article in the March 2022 edition of Processing Magazine. The article is titled “Alternative Control Valve Repair Solution Yields Savings” and it describes how a new hybrid repair/replace control valve repair solution can reduce repair time by 60%, while increasing plant uptime considerably. A summary of the article follows.

Traditional valve repair
Control valve repair is an expensive and challenging aspect of plant maintenance. These types of valves can be quite costly, so a simple replacement of the valve rarely makes financial sense. Therefore, the plant has little choice but to pull the valve, disassemble it, and identify and replace the failed components. However, a valve is composed of a broad array of internal parts (Figure 1), and it is difficult to determine which has failed until the valve has been fully disassembled. Even assuming all the parts required for the repair are available, the job is quite daunting as Emerson explains:

It takes a fully trained technician to diagnose, repair and properly reassemble the valve to restore it to functionality. Adding to the difficulty, the precision required to do this work means it can typically not be performed in the field, but instead must be done in a repair shop.

Figure 1: Control valves have many internal components that may require replacement during a repair, and all must be available before even starting. Proper reassembly of these numerous parts is critical for valve performance.

Once the repair is complete, there is still the risk that the problem was never fully identified, and the “repaired” control valve may fail to perform. It may also be reassembled incorrectly. In either case, the result is curtailed production, and possibly a complete unit shutdown.

Fortunately, a new option dramatically simplifies the control valve repair process with a streamlined approach, using a single assembly instead of multiple small parts.

Trim cartridge alternative
A new method of control valve repair has recently been introduced, offering significant advantages. A trim cartridge (Figure 2) is a single, pre-assembled repair solution that replaces all the components shown in Figure 1. This includes a valve bonnet, standard trim and packing replacement parts—as well as a plug and seat assembly.

Figure 2: A trim cartridge replaces up to 20 individual internal components with one drop-in assembly. Installation requires minimal training and makes inline valve repair possible.

Emerson describes the new repair component:
A trim cartridge is a single, ready-to-install repair solution containing all the replaceable trim parts incorporated in a pre-assembled, leak-tested, and serialized package.

The valve repair is fast and quite simple, usually requiring little technical training since it only involves replacement of the bonnet and trim (Figure 3). With proper line isolation, the repair can be completed without removing the valve body from the line, further conserving valuable trained technical resources, and significantly reducing downtime.

Figure 3: A trim cartridge installation replaces the bonnet and all trim parts, and it can be performed without removing the valve body from the process.

The trim cartridge has an added benefit as Emerson explains:

The repair replaces all serviceable parts plus the bonnet and does not require significant field adjustment. This dramatically improves the likelihood that the repair will be successful the first time.

The Fisher trim cartridge is backwards compatible for Fisher easy-e ET and EZ series control valves, and it incorporates ENVIRO-SEAL packing as a standard offering. It is offered in valve sizes from one to four inches, with a wide variety of trim and component materials, and both linear and equal percentage trims.

Evaluating options
Any successful maintenance strategy considers the cost of equipment repair against the cost of replacement to determine the most cost-effective option. The trim cartridge offers a hybrid alternative, allowing plant personnel to perform a partial replacement that quickly restores a control valve to service, an approach well suited for emergency repair of critical valves. It also allows a plant to easily upgrade to Enviroseal packing to reduce emissions. When a plant is faced with an overworked maintenance staff and is under pressure to make valve repairs quickly, a trim cartridge repair solution is often the best option.

All Figures courtesy of Emerson