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Finnish firm Wärtsilä has announced that its Airguard and Oceanguard propeller shaft sealing systems can continue to utilise mineral oil since they meet the guidelines set out in the US Environmental Protection Agency's (EPA) 2013 revised Vessel General Permit. The guidelines came into force in December 2013 and the position of the Environmental Protection Agency was published in a webinar organised by the EPA on 14 February 2014.

This means that the Airguard and Oceanguard seals meet the defined regulatory prerequisites and that owners and operators of commercial vessels of over 79ft (24 metres), sailing within US waters with either of these Wärtsilä systems installed, are not required to change to an Environmentally Acceptable Lubricant (EAL).

With the Wärtsilä Airguard and Oceanguard propeller shaft sealing systems there is no oil-to-sea interface, according to Wärtsilä. An air chamber or separation space within the seal captures any water or oil leakage, which is then transferred to inboard tanks for monitoring and further treatment. This completely eliminates oil drips or leakage into the sea, the Finnish firm claims.

The EPA requires these designs to be functioning normally, which can be assured by proper operation and maintenance according to Wärtsilä's guidelines. In case of system failure, both systems are also said to prevent 'any reasonable possibility of oil leakage', which is the second criterion for the continued use of mineral oils.

Wärtsilä offers customers a full range of solutions that promote environmental sustainability. Its portfolio of seal solutions ranges from Bio Seal Rings to some of the most advanced environmental seals on the market.

"The Airguard and Oceanguard propeller shaft sealing systems have a long, proven, and successful operational track record," Wärtsilä said. Upgrade and retrofit options are also available.

Most commercial stern tubes are of the oil lubricated type and require a robust and reliable sealing solution. Wärtsilä has several years of experience in developing the technologies behind its range of oil lubricated sealing products, which includes both face and lip seal variants to deal with a wide variety of operating profiles. The systems are designed to withstand abrasive waters and are compliant with all anti-pollution requirements.