Siem Stingray’s seawater cooling system «as new» after 5 years without maintenance

The seawater cooling system on board Siem Stingray had not been cleaned once in five years. Nevertheless, Siem Offshore had not experienced any problems with cooling of the main engine or other auxiliary systems during the period.

Before and after cleaning

Before and after cleaning

For Siem Offshore, this means lower operating costs as well as increased operational vessel uptime, which translates to better earnings for the company.

The seawater cooling system, called “Rack”, has been supplied by Hydroniq Coolers. The Rack system is integrated in the hull below the deck of Siem Stingray’s main engine room. The system is utilised to prevent overheating of the ship's engine and other auxiliary systems on board. 

In comparison: if shipowners use standard plate heat exchangers to cool down the main engine on an offshore construction vessel, they expect to clean the system at least once a year. 

Although the Rack seawater cooler is designed to increase intervals between cleaning, Hydroniq Coolers does not recommend sailing for five years without cleaning the system.  The recommendation is to quickly clean the system monthly through use of compressed air. The coolers can easily be extracted from below the engine room even when the ship is at sea.

“One of the main reasons for why Siem Stingray could operate safely for five years without cleaning the Rack seawater cooling system, is because the vessel’s system has been designed for a seawater temperature of 32 degrees, while the vessel had operated in waters with lower temperature. The temperature difference provides the shipowner with a significant safety margin with regards to maintenance requirements,” says Lars Elling Gloppholm, sales manager for aftermarket and services at Hydroniq Coolers. 

Siem Offshore extracted the Rack seawater cooling system during the five-year classification of the Siem Stingray at Orskov Shipyard in Fredrikshavn, Denmark.  

Photo: Siem Offshore

Photo: Siem Offshore

After cleaning the Rack coolers with the eco-friendly cleaning and degreasing agent MultiScale, "the bundles looked like they were brand new", according to vessel manager Stig Rune Nilsen at Siem Offshore who was responsible for the inspection. There were no signs of wear on the crates in which the "Rack" system is placed, or the CuNi tubes in the bundles.

Siem Stingray is currently on a bareboat charter with Swire Seabed, who in this connection has renamed the vessel Seabed Stingray

Hydroniq Coolers has delivered seawater cooling systems to Siem Stingray’s three sister vessels – Siem Day, Siem Barracuda and Siem Spearfish – too. These vessels have also undergone the first five-year classification, with the same conditions of the Rack cooling system. 

Hydroniq Coolers delivers marine cooling solutions to vessels that operate within offshore, shipping, cruise, passenger transport, fishery and fish farming. The company is owned by Norwegian investment company SMV Invest AS (formerly Sperre Mek. Verksted AS).

Hydroniq Coolers AS