Power plants are often faced with deciding whether to repair or replace critical valves when a failure happens, or an inspection indicates imminent failure. There are various factors to consider when making this type of decision.
Of course, there are situations when the answer is obviously replacement – when the valve simply cannot be repaired. However, replacing critical valves can have an extended lead time or be prohibitively expensive.
Power plants typically plan scheduled outages to perform preventive maintenance on equipment, including critical valves, identifying potential issues or damage. The shutdown timeframe may not be sufficient for the procurement and installation of critical valves, leading to more downtime than planned.
Which Valves Are Critical?
Some valves in a facility are more critical than others. In a power plant, these are typically large-diameter, in-line high-pressure, severe service, high-cost valves. Because these valves are more crucial to plant operation, they generally are inspected and undergo maintenance on a more frequent schedule than non-critical, lower-cost valves. During the inspection process, it is common to discover damage to the valve seat, disc, and other valve components.
Repair of critical valves can require time, technology, and special expertise, resulting in high costs. The plant owner, or decision-maker, will have to determine which is best for the business, repair, or replacement. In some cases, the decision is easy because replacing the valve isn’t an option. High-value valves take longer to procure, and it may simply not be possible within the outage window. In those cases, repair is the only viable option.
Repairing Critical Valves
A thorough investigation of the defective valve must be made to determine if repair is an option. This typically involves disassembly of the valve, down to its component parts, to diagnose the problem. Once all the parts are inspected and a diagnosis is made, an estimate of the cost can be determined, and the plant owner can decide if repair is best for the situation.
Cost isn’t the only consideration when determining whether a repair is the right option. It is also important to ensure that the needed repairs can be accomplished within the outage window. When a critical valve is repaired, it may require replacement components or in-line repair. That can present a problem for various reasons. First, it may simply take too long, extending the downtime. Secondly, the cost of repair must be weighed against the cost of future replacement.
Replacement of Critical Valves
Replacing critical valves may be a good option in some cases, especially when the cost of repair (for parts, labor, and estimated downtime) is close to a replacement cost. This option may reduce unexpected delays, but only if a replacement valve is readily available. A replacement may be easier in calculating the overall cost upfront, whereas total repair costs may not be determinable until much of the work is completed.
Logistically, replacing critical valves may seem like a better option. However, there are some drawbacks to replacing critical valves as well. The cost of replacement may be significantly higher than a repair, making it cost-prohibitive. If the repair can be done on a short turnaround, it may be a better choice than the more expensive replacement.
Final Thoughts about Critical Valve Maintenance
It would be nice if critical valve repair was more predictable and the cost was easier to estimate. It would make it much simpler to decide which option is best for critical valve maintenance. But since that isn’t the case, it’s essential to find a valve repair company that can provide mobile machining, welding, repair, and testing expertise. The best option is to find an independent repair company that can help you make the best decision regarding repair, availability of replacement parts, or provide several suitable replacement options for your issue onsite at your facility. The critical valves or their components will not have to be taken offsite, the quality of work can be monitored, outage schedules can be maintained, and a sounder business decision can be made.