Lower cost stern tube seal repair

25 Jun 2013
Underwater seal repair provides an economic alternative to drydocking, says Wärtsilä

Underwater seal repair provides an economic alternative to drydocking, says Wärtsilä

According to Wärtsilä, stern tube seals, mounted between the propeller and the stern tube, are vulnerable to damage due to the hazards present in the subsea environment. Operating with a damaged seal risks environmental pollution and failure of the stern tube bearings, either of which can result in a vessel being unable to sail, costing the owner time and money.

The company says that failure may occur when a stern tube seal is compromised by a foreign object such as fishing line, or by environmental abrasion. When this happens, the seal must be repaired or replaced before the ship can sail again. Such incidents often occur when the vessel is far from its home maintenance port.

Wartsila says that it can manage and quickly fix problems resulting from stern tube seal damage, being able offer short lead times for stern tube seal repair or replacement, thanks to its expert supply chain management. The company says that it is able to engineer a seal for the customer’s need; then manufacture, deliver and install it – all within a few days’ notice, at any location.

The company can additionally repair stern tube seals underwater, which it says can sometimes offer a cost-effective alternative to dry-docking an offshore vessel, which can cost tens of thousands of dollars per day. Underwater servicing means that a team of diving engineers conduct the repair either in open water or in a de-watered hyperbaric chamber. Working in the hyperbaric chamber resembles working conditions in a normal dry dock. The vessel needs only to be secured at a location where sea conditions allow for safe underwater repair.

Wärtsilä says that its seal engineers are able to react within minutes when a customer reports a problem. Chris Rowlands, director of Swedish subsidiary Wärtsilä Seals & Bearings, comments: “We design a seal that suits the customer’s vessel by using 3D parametric CAD tools to reduce the risk of error. Next, the main components are cast by our in-house foundry and machined using our state-of-the-art CNC machine tools. Finally, the finished seal is assembled and tested. In most cases, this stage is performed by the engineers who will actually install the seal on the customer’s vessel, helping to ensure the highest quality.”

Wärtsilä Sternguard SeaQual seals are said to be robustly designed for long life running in demanding operating conditions. They are fully-split, meaning that they can be fitted without propeller shaft withdrawal. The short length of the Sternguard SeaQual seals allows them to be easily retrofitted.

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Wartsila Corporation

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