Steam turbine valves control steam admission, load regulation, and overspeed protection. These valves operate under extreme conditions, high temperatures, high pressures, and rapid cycling, and their components are subject to erosion, seat leakage, stem scoring, and actuator wear.
AQ Process Systems sources and exports replacement internals and actuator components for all turbine valve types, main stop valves (MSV), governor/control valves (GV/CV), reheat stop valves (RSV), intercept valves (IV), and extraction check valves. We support valve overhauls during planned turbine outages.
Turbine valve condition directly affects both safety and efficiency. A leaking main stop valve compromises overspeed protection; worn governor valve seats cause load swing and poor heat rate. We supply parts that restore valve performance to design specification.
| Component | Specification | Description |
|---|---|---|
| Main Stop Valve (MSV) | ||
| MSV Valve Seats | Stellite-faced | Lapped seating surface | Main stop valve seats, Stellite hardfaced for erosion resistance, lapped to achieve leak-tight shutoff. |
| MSV Valve Stems | Alloy steel | Chrome-plated | Ground finish | Valve stems with chrome-plated surface for wear resistance and compatibility with packing and bushings. |
| MSV Discs / Plugs | Stellite-faced | Matching seat geometry | Valve closure elements, Stellite-faced disc or plug matched to the seat for positive shutoff. |
| MSV Stem Packing | Graphite or braided PTFE | High-temperature | Valve stem packing sets preventing steam leakage along the stem, replaced during every valve overhaul. |
| Governor / Control Valve | ||
| GV Valve Seats & Plugs | Stellite-faced | Profiled for flow characteristic | Governor valve seats and plugs, precisely profiled to achieve the required steam flow characteristic (linear or equal-percentage). |
| GV Valve Stems | Alloy steel | Chrome-plated | Governor valve stems with chrome plating and ground finish for smooth actuator response. |
| GV Bushings & Guides | Stellite or bronze | Stem guide bushings | Valve stem guide bushings maintaining stem alignment and preventing lateral movement. |
| Extraction & Intercept Valves | ||
| Extraction Check Valve Internals | Disc, hinge pin, dashpot | CS or SS | Internal components for extraction line non-return valves, preventing reverse steam flow during turbine trip. |
| Intercept Valve Internals | Seat, plug, stem | Reheat steam duty | Internals for reheat intercept valves, controlling reheat steam admission to the IP turbine. |
| Valve Actuators / Servo Motors | Hydraulic or electro-hydraulic | Trip-capable | Valve actuator assemblies providing fast-close capability for overspeed protection, servo motors, cylinders, and accumulators. |
Parts are manufactured to OEM specifications with full material certification, dimensional inspection, and NDE documentation as required. Provide the turbine manufacturer, frame/model designation, and part number for precise identification.
The most common spares are valve seats and plugs/discs (erosion and seat leakage), valve stems (scoring and wear), stem packing (leakage, replaced every overhaul), stem guide bushings (wear), and actuator seals and springs. All valve seating surfaces should be inspected and lapped or replaced during major overhauls.
Valve seats are specified by the valve model, seat bore diameter, outside diameter, hardfacing material (typically Stellite 6 or 21), seat angle, and surface finish requirement. The seat must match the disc/plug, seats and discs are usually lapped together as matched pairs.
Governor valves throttle high-pressure, high-temperature steam across a small opening at partial loads, the resulting high velocity causes solid particle erosion (SPE) and wire drawing of the seat and plug surfaces. Stellite hardfacing resists this erosion, but eventually the surfaces degrade and must be reground, re-hardfaced, or replaced.
Yes. We supply hydraulic and electro-hydraulic actuator components, servo motors, hydraulic cylinders, control oil accumulators, trip solenoids, position feedback transmitters, and hydraulic seals. Actuator response time is critical for overspeed protection, components must meet the original closing time specification.
Extraction check valves are non-return valves in the steam extraction lines supplying feedwater heaters. During a turbine trip, these valves close rapidly to prevent steam from the feedwater heaters flowing back into the turbine, which could cause overspeed. Fast-close performance is regularly tested.
Share your turbine make, model, and part numbers, we respond within 24 hours.