Turbine seals prevent steam leakage at shaft penetrations and between stages. Labyrinth seals, the primary sealing mechanism in steam turbines, use a series of restrictive clearance gaps to throttle leakage flow without contact. Over time, rub events and thermal cycling open these clearances, increasing leakage and reducing efficiency.
AQ Process Systems sources and exports replacement labyrinth seal segments, carbon ring shaft seals, gland packing, and complete gland system components including gland condensers and seal steam regulators. We support both casing-mounted and rotor-mounted seal configurations.
Restoring seal clearances during overhauls is one of the most cost-effective turbine efficiency improvements, reducing interstage leakage and shaft end losses directly increases power output and heat rate.
| Component | Specification | Description |
|---|---|---|
| Labyrinth Seals | ||
| Labyrinth Seal Segments | Brass, SS, or nickel alloy | Casing-mounted | Casing-mounted labyrinth seal ring segments, machined to maintain design tip clearance with the rotor. |
| Seal Strips / Fins | Caulked or welded into grooves | Various profiles | Individual labyrinth seal strips (teeth) installed in grooves in the seal ring body, T-shape, J-shape, or knife-edge profiles. |
| Interstage Seal Rings | Segmented | Spring-backed or fixed | Seals between turbine stages reducing internal steam leakage that bypasses the blade path. |
| Shaft End Seal Rings | HP and LP end seals | Multi-ring sets | Shaft end labyrinth seal ring sets preventing steam leakage to atmosphere at the turbine shaft exits. |
| Carbon Ring Seals | ||
| Carbon Ring Segments | Carbon graphite | 3 or 4 segment rings | Segmented carbon ring seals, spring-loaded against the shaft for positive contact sealing at shaft ends. |
| Garter Springs | SS | Holding carbon segments against shaft | Circumferential springs maintaining carbon ring segment contact pressure against the rotating shaft. |
| Gland System | ||
| Gland Condenser | Shell & tube | Condensing leak-off steam | Gland steam condenser extracting and condensing steam leaking through the shaft end glands, maintaining sub-atmospheric pressure at the gland exhaust. |
| Gland Exhaust Fan | Centrifugal | Creating slight vacuum at gland | Exhaust fan maintaining slight vacuum at the outer gland, drawing leak-off steam to the gland condenser. |
| Seal Steam Regulator | Self-acting or pilot-operated | Pressure control | Pressure regulators controlling seal steam supply pressure to the turbine glands during startup and low-load operation. |
| Gland Packing | Graphite or PTFE rope | For packed-gland turbines | Shaft packing sets for older turbines with packed glands rather than labyrinth seals. |
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 seal spares are labyrinth seal segments (rub damage opens clearances), seal strips/fins (bent or worn), carbon ring segments (wear), garter springs (fatigue), gland packing (for packed-gland turbines), and gland condenser tubes (corrosion). Restoring design clearances is a priority for efficiency recovery.
Worn labyrinth seals can reduce turbine efficiency by 1-5% depending on the severity. Interstage seal leakage bypasses the blade path, reducing work output. Shaft end seal leakage wastes steam directly. Restoring clearances during overhauls typically recovers 0.5-2% in heat rate improvement, often the most cost-effective single efficiency measure.
Seal ring bodies are typically brass, stainless steel, or nickel alloy depending on the temperature zone. HP and IP seals use high-temperature alloys; LP seals often use brass. Seal strips (fins) are typically stainless steel or nickel alloy, chosen to be softer than the rotor material so they preferentially wear during rub events.
Yes. We supply replacement gland condensers (shell & tube type) and gland exhaust fans. We also supply individual tube bundles for retubing existing gland condensers, as well as seal steam regulators and all associated valves and piping components.
Seal steam is low-pressure steam supplied to the turbine shaft end glands during startup and low-load operation, when the turbine's own internal pressure is insufficient to prevent air ingress through the glands. Air ingress into the condenser degrades vacuum and reduces output. The seal steam regulator automatically adjusts supply as turbine load changes.
Share your turbine make, model, and part numbers, we respond within 24 hours.