1. When should a valve be refurbished instead of replaced?
Refurbishment is recommended when the valve body is structurally sound but the valve no longer performs optimally. Symptoms such as poor control response, leakage, excessive wear, or failure to meet process requirements can often be corrected through component replacement, repair, recalibration, and performance testing. Compared to complete replacement, refurbishment offers significant cost and lead-time savings while restoring, and in many cases improving, valve performance and reliability.
2. How can spare parts be sourced for obsolete or legacy valves?
If OEM spare parts are obsolete or unavailable, experienced valve specialists can reverse engineer and manufacture fully interchangeable or upgraded replacement components. Choosing a partner with expertise in valve design, custom engineering, manufacturing, refurbishment, testing, and field service ensures reliable, cost-effective solutions that can restore—and often enhance—the performance and service life of legacy valves.
3. What are the common causes of control valve failure?
Improper sizing, erosion, corrosion, cavitation, poor maintenance, actuator issues, and incorrect material selection are among the most common causes.
Over the life of a plant, the operating conditions of a control valve often change significantly from the original design basis due to process modifications, capacity expansion, debottlenecking, changes in feedstock, or new end-product requirements. As a result, valves may operate far outside their intended design envelope, leading to poor control performance, increased erosion, cavitation, vibration, excessive noise, frequent maintenance, and reduced service life. Evaluating the revised operating conditions and upgrading the valve trim, actuator, or other critical components can restore optimal performance and significantly extend valve life.
4. How can control valve performance be maintained when operating conditions change significantly?
Yes. Control valve performance can often be restored by reviewing the revised process conditions and upgrading the valve trim, actuator, materials, or flow characteristics to suit the new operating requirements. For significant changes in operating conditions, engineering tools such as CFD and FEA can be used to optimize the design and validate performance. These upgrades are best undertaken by valve specialists experienced in design optimization, retrofitting, and performance enhancement.
5. What causes cavitation and flashing in control valves?
Cavitation and flashing occur when the fluid pressure falls below its vapour pressure within the valve. They can be minimized through proper valve sizing, appropriate valve selection, and the use of specialized trims. In practice, one of the most common causes is an oversized or over-rated control valve, which operates at low openings and creates excessive pressure drop, leading to cavitation, vibration, noise, and premature wear.
6. How can valve noise be reduced?
Using low-noise trims, multi-stage pressure reduction, optimized flow paths, and proper valve sizing can significantly reduce noise levels.
7. How can valve service life be extended?
Proper valve selection, preventive maintenance, timely replacement of wear parts, suitable materials, and operating within design limits significantly improve service life.
8. Can obsolete valves be reverse engineered and upgraded?
Yes. Reverse engineering and design upgrades can restore the performance and extend the service life of legacy valves when OEM spares are no longer available. Retrofitting modern actuators, digital positioners, or upgraded valve trims often provides a new lease of life, delivering improved control performance, higher reliability, enhanced diagnostics, and lower lifecycle costs compared to complete valve replacement.
