Riviera – Knowledgeable opinion – Wärtsilä Sternguard E seals: 25 years of design excellence
Just one possibility is out there for the outer seal, the Wärtsilä Sternguard EK slotless mannequin. Not like inner seals, the EK doesn’t want a clamp as it’s compressed between the propeller and the rear body. This association additionally ensures that there isn’t a put on to the shaft or the liner, lowering the necessity for the shaft to be eliminated and refurbished later.
Normal and abrasion resistant fashions of the EK variant can be found and each may be provided with oil ports on request. These seals are perfect for use with small thrusters or the place the propeller is detachable; different Wärtsilä gaskets can be found to be used with giant thrusters.
All Wärtsilä Sternguard E gaskets have rubber our bodies, which eliminates any chance of galvanic corrosion that might happen if metallic springs have been used. It additionally adapts to axial, radial and angular actions of the shaft and kinds the loading element of the seal, imparting ample axial drive to create a seal in opposition to the metallic face of the seal.
This face is an integral a part of the seal physique for the unsplit Wärtsilä Sternguard EJ and EK variants, whereas the cut up faces of the Wärtsilä Sternguard EL kind are held in a phosphor bronze face holder, with a sealing strip to seal the face. ‘facial insert. within the help and apply a radial compressive load to it. The seal additionally has a drive pin, as described above, which permits simultaneous rotation of the physique and face of the seal. The gasket seat is a straightforward changeable flange. For the Wärtsilä Sternguard EK seal, this can be a seat insert supported by two concentric O-rings.
Rubber has a lifespan of 10 years from the date of drying and this date is indicated on supply. A inventory of those rubber gaskets is stored on the Wärtsilä Spain manufacturing unit in diameters from 50 mm (Wärtsilä Sternguard EK and EJ) 70 mm (Wärtsilä Sternguard EL) to 330 mm (for all variants), in order that the acquiring spare and substitute elements is fast and straightforward. Inventory can also be obtainable for non-machined our bodies.
Inventory ranges and turnover are such that there’ll possible be a minimum of eight years of use remaining when a brand new gasket is delivered or the rubber element is provided as a spare.
A particular software is supplied to put in the inside seals, which compresses their rubber sealant to its right size whereas a clamp is connected to keep up that dimension; no different specialised instruments are wanted to put in the gaskets.
No pliers are wanted for the outer seal, which is compressed between the propeller and the rear body, and in water lubricated methods an outer seal will not be required if the rear bearing has a ” association. open water ”. For purposes the place the strict tube and propeller hub are very far aside, an outer model of the Wärtsilä Sternguard EJ seal may be fitted. This may be certain that the drive clamp can safe the working distance and rotation of the joint physique with the shaft.
All three seals have the identical efficiency and design options, and all are supported by robust but versatile elastomer our bodies with built-in face inserts. This maintains the integrity of the seal regardless of the radial and axial actions of the shaft. In use, inside seals may be checked with out drydocking if the seal has an extra inflatable seal possibility, lowering upkeep downtime and giving operators extra time to concentrate on different operational points of their vessel.
All three variations may be provided with or with out inflatable seals (solely beneficial for Wärtsilä Sternguard EJ and EL seals), that are actuated by air or fluid stress and compressed on the shaft.
The desk beneath summarizes the primary traits shared by the completely different fashions:
Benefits of the face seal
Not like most gaskets used on midsize ships, Wärtsilä Sternguard E gaskets are face gaskets, providing important operational benefits over extra ordinary lip gaskets. Whereas lip seals create a seal in opposition to the shaft, face seals use the compression between two surfaces perpendicular to the shaft to type a seal. Which means that there’s minimal put on on the shaft and permits for higher radial motion, which might in any other case break the seal or harm the shaft if a lip seal was used.
Face seals are additionally extra compact than lip seals, which require a sure size alongside the shaft line to create chambers for the oil, however Wärtsilä Sternguard E seals are significantly compact attributable to their easy development. .
A face seal can also be simpler to chill when wanted for oil lubricated or closed water lubricated methods. The coolant may be routed just a few millimeters close to the friction factors, that are on the faces moderately than the shaft sleeve, as can be the case with lip seals.
Face seals additionally work finest if the shaft bearing has to put on down, inflicting the shaft itself to maneuver decrease within the bearing. The face seals are usually not affected by this motion, however the lip seals would endure a change of their compression, which might result in water infiltration.
This can be a results of how each sorts of seals expertise friction: for face seals it’s axial whereas lip seals face radial friction. Because of this, any change within the place of the shaft within the bearing impacts the purpose of contact of the shaft of a lip seal and due to this fact its effectiveness, whereas for a face seal it merely adjustments the placement of the shaft. contact level however doesn’t make any important change in seal efficiency.
This temporary overview of Wärtsilä Sternguard E gaskets highlights their versatility and ease, which mix to make them the perfect alternative for small to medium sized business purposes. Whatever the bearing lubrication system and working setting of the vessel, these seals present a compact and dependable answer for each stern shafts and rudder inventory.
Mixed with wonderful after-sales service backed by a fast provide of spare elements in inventory, Wärtsilä Sternguard E Face seals present compact, competitively priced, dependable and sturdy companion know-how for any bearing set up.