Extend the life of your Kaplan turbines:

Discover the innovative sealing solution from PXL SEALS

In the field of hydroelectricity, Kaplan turbine operators understand the importance of blade sealing. Failure of these components can result in an immediate halt to electricity production, causing economic losses that can amount to hundreds of thousands of euros.

With over 30 years' experience, PXL SEALS has developed a specially designed sealing solution for the blades of vertical and horizontal Kaplan (bulb) turbines, making operations safer and significantly extending turbine life.

How can the PXL SEALS sealing solution extend the life of your Kaplan turbines?

The answer lies in a fully tried-and-tested, comprehensive solution combining a set of seals and compensation rings that enable the optimal positioning of the seal within the housing, a unique MD WAY® on-site moulding process and the expertise of our service teams.

1. A seal profile specifically designed for hydroelectric turbine blades

The PXL SEALS solution is based on a one-piece, fully-molded seal: the U150-XI DE profile.

This joint is the result of decades of research and feedback from the field on Kaplan turbines. It takes into account not only the problems of the application itself, but also those of previous solutions, such as chevrons and back-to-back U-joints.

This tried-and-tested solution has been optimised regularly for over 20 years to address all the new problems encountered in the field. Its main advantages are :

• Easy-to-install single seal


• Good positioning in the housing


• Preservation of housing condition over time


• Can be molded on site using PXL SEALS’ MD Way system

This one-piece joint is moulded as a single unit with no joints, offering perfect dimensional consistency across its entire diameter.

This design guarantees stability in the housing, easy assembly, and a double-acting seal (oil/water and water/oil), which is essential for the safety and efficiency of installations.

Designed for both original equipment (OEM) and maintenance (MRO), the sealing system can be installed in most cases without reworking the housings.

2. The seal - ring combination to preserve the housing

The solution developed by PXL SEALS is not limited to the seal itself, but encompasses the entire sealing system, including seals and compensation rings. The rings are placed between the housing and the seal, enabling the seal to be positioned in the healthiest area of the housing to achieve the best possible sealing.

In new installations, the seal assembly with compensation rings preserves part of the housing: the seal is positioned on the water side and the oil side includes the compensation rings. During maintenance, the seal can be shifted to the oil side by moving the compensation rings. This means that the seal lips can continue to be applied to healthy surfaces that were previously maintained in oil.

The result is major time and cost savings, since the seal only needs to be positioned in a small part of the housing. This enables successive maintenance operations to be carried out without the surfaces (hub and blade) needing to be reworked.

3. The exclusive MD WAY® on-site molding process and the HLB hot-joint

Another decisive advantage is the patented MD WAY® process, developed and used exclusively by PXL SEALS. This technology enables molded joints to be made directly on site, without dismantling the equipment.

• A factory-like quality joint
  
  With mechanical and chemical resistance superior to conventional hot or cold finger-jointing methods.


• Easy to install!
  
  The MD WAY® process can be adapted to suit any site configuration, even in cases where access is difficult or there are severe constraints.


• Comprehensive expertise and a team that makes all the difference
  
  Every project includes a metrological assessment of the housing (eccentricity, surface conditions, tolerances), custom design of the sealing system, and preparation and installation of the elements. This expertise guarantees the long-term reliability of the solution.

However, the MD-WAY process is subject to a number of dimensional constraints. For blade trunnion dimensions that are too small, the alternative is our HLB hot-joining process. Although this process has slightly inferior characteristics to MD-WAY, it is still far superior to cold bonding.

4. Examples and feedback:

The PXL SEALS solution has already been adopted by numerous hydropower locations. Here are just a few examples:

- Sealing of Kaplan turbine blade bearing trunnions without dismantling

In order to ensure optimum production continuity while minimising plant downtime, PXL SEALS has replaced the traditional sealing method for Kaplan turbine blade trunnions at several hydropower plants, using the exclusive MD WAY® on-site moulding process.

On-site interventions included all or part of the following services:

• Design and installation of the sealing system;


• Metrological inspection of housings (e.g. eccentricity);


• Inspection of surface finish;


• Preparation of housings;


• Moulding and seal assembly.


• Delivery of a complete work report.

These activities were carried out on Kaplan turbines in France and abroad.

- Replacing blade trunnion seals on bulb turbines at the La Rance tidal power plant.

• Design and manufacture of the sealing system;


• Supply of scaffolding;


• Removal and reinstallation of seals;


• Implementation of turbine rotations;


• Metrological inspection of housings (e.g. eccentricity);


• Inspection of surface condition, including quantification of journal wear;


• Preparation of housings;


• On site moulding using the MD WAY® process and fitting of seals;


• Requalification implementation;


• Delivery of a complete intervention report.

- Replacement of blade trunnion seals with on-site reworking of the housings.

PXL SEALS took up the challenge of a complex intervention on a bulb turbine in operation: severe wear to the hub and trunnions, and significant variations in the cross-section of the housings (subsidence). Dismantling the turbine was not feasible given the scale of the project.

In response to these constraints, PXL SEALS developed a specific technique for reworking the housings and eccentricities on site without machining.

This innovative solution enabled us to use our U150-XI DE seal, which is joined via the MD WAY® process. This would not have been possible without the housing recovery.

Solution deployed:

• Assessment of the dimensions and quality of the units;


• Design of the wear and eccentricity recovery system;


• Installation of surface and eccentricity recovery systems;


• Re-appraisal after installation;


• Design and manufacture of seals;


• MD WAY® on-site moulding and assembly of seals and rings;


• Delivery of a full service report;
  
  The oil was requalified and the turbine was refilled as normal, ensuring continuity of operation.

The Kaplan blade seal solution from PXL SEALS offers a comprehensive and long-lasting response to the demands of the hydroelectric industry.

Thanks to its high-performance, one-piece design, adjustable compensation rings and exclusive MD WAY® process, it helps secure installations, minimise equipment downtime and prolong the lifespan of all machinery, regardless of operating conditions.

See also the full range of seals for hydropower

More information on on-site jointing processes

Tags : Kaplan seals, blade seals, PXL seals, sealing system, hydropower