Sealing Solutions for Hydrogenerators and Hydropower Plants

Hydrogenerators and hydropower plant equipment present a distinct set of sealing requirements. Project Sales Corp supplies the correct sealing compounds for Indian hydropower applications, including Niel-Seal for hydrogen-cooled generator end-shield groove sealing.

India operates one of the world's largest installed bases of hydropower capacity. The turbines, generators, and auxiliary equipment in these plants have long overhaul intervals and are expected to operate reliably between major maintenance events that may be separated by a decade or more.

The sealing requirements in a hydropower plant differ in character from those in a thermal power station. Water turbine casings operate at relatively low temperatures compared to steam turbines, but the joint areas are large, the media include water under head pressure and turbine oil in the bearing and governor systems, and many hydrogenerators are hydrogen-cooled — which introduces a specialised sealing requirement for the generator end-shield groove joints.

Hydrogen-Cooled Generator End-Shield Groove Sealing — Niel-Seal

Large hydrogenerators cooled by hydrogen gas require a purpose-engineered compound for the groove channels between the end-shield halves and the stator housing. Standard silicone sealants and general-purpose compounds are not suitable for this application. Niel-Seal (formerly Tite-Seal® by Abbey Products) is purpose-engineered for exactly this joint — injected into the groove channels, remaining permanently flexible in service, and unaffected by water, oil, steam, ammonia, glycerin, and most gases.

Niel-Seal is available in two grades: Light-Weight for applications requiring greater pumpability through narrow groove channel geometries, and Medium-Weight where a thicker film or heavier compound is required. Grade selection is based on the specific groove channel geometry and consistency requirement of the generator end-shield design.

Turbine Casing and Structural Joints

For the metallic parting-plane joints of Francis, Kaplan, and Pelton turbine casings — where the surfaces are sound and damage is within ≤0.2 mm — BIRKOSIT (900°C, 250 bar) or FILLING Basic (950°C, 275 bar) are the appropriate sealing compounds. Where surface damage has accumulated over decades of service, FILLING 1000 (≤0.5 mm) or FILLING 2000 (≤1.0 mm) with FILLING Basic is correct.

Generator Bearing Housings

Hydrogenerator bearing housings are flanged assemblies operating on turbine oil at modest temperatures. Arexons Motorsil D Red is suited to these housing joint faces where a formed-in-place silicone gasket is appropriate — but suitability must be confirmed against the specific operating conditions, oil type, and temperature for each application.

Application Summary for Hydropower