Emergency Shaft Seal Bladder Systems

Wartsila Seal Bladder System Tested on Shaft

Many of the large “Class” vessels have seal systems such as Wartsila or Duramax that have an emergency inflatable bladder.  The system is basically an inflatable bladder (like a bicycle tire tube but far more durable) that is housed just aft of the ships seal system.  If there is damage to the seal, air pressure is applied from a ship’s compressor or simple bicycle pump to inflate the bladder.  The air press causes the bladder to tighten around the shaft and slow the leak to a small drip.  If the system is operating properly it should maintain air pressure for hours.  However, the systems are not designed to withstand the friction of the shaft turning.  Usually the vessel has a shaft brake system to allow movement with one engine without the “down” shaft from turning.

We have just completed a 5 year ABS inspection on the running gear on a 121′ Heesen.  We removed the Wartsila seals and tested the inflatable bladder at the shop.  The picture below shows the set-up on the shaft (145 mm shafts).  The video above shows the inflation of the bladder using a simple bicycle pump.  It is a good thing we tested the bladder.  We found the fittings on one side to be loose and would not hold air pressure for more than a few seconds.

Confidence at sea comes from careful preparation and testing of all the ship’s systems.