Unprecedented activity in FPSO and FSO projects has boosted demand for Saab Rosemount Marine’s tank gauging systems. Even before mid-year, the company had booked seven deliveries of its Saab TankRadar STaR system.
The Saab TankRadar tank gauging system will feature in numerous new FPSO and FSO projects.
The latest order is for ConocoPhillips’ FSO Belanak, which is being converted at the Singapore Technologies Marine yard. The equipment must be delivered within two-three months, according to offshore sales manager Jan Wallberg. Another current delivery is to Total’s Akpo FPSO, to be installed off Nigeria, which will have oil production capacity of 225,000 b/d. The STaR package will be integrated into the FPSO automation system.
In March a STaR system was delivered to Berge Enterprise, the Bergesen tanker undergoing conversion for duty on Pemex’s Ku/Maloop/Zaap field complex in the Mexican sector. This will be the world’s largest FPSO, with storage capacity of 2.4 MMbbl and total throughput, of 600,000 b/d.
Accuracy benefits
Since 1986, Saab Rosemount Marine has supplied tank gauging systems to more than 75 FPSO/FSO units. It also claims to be the world-leading supplier of such systems to oil tankers, where it has 53% of the world market, according to Wallberg. For LNG carriers there is a dedicated product, the Saab TankRadar CTMS - custody transfer measurement system. In this market the company has a 63% share.
The STaR tank gauging technology is based on the radar expertise Saab developed originally for aeronautic and military applications. More recently it has been extended by Saab Rosemount Marine to monitor wave height and sea profile around offshore installations.
For tank gauging purposes, the system employs the frequency modulated continuous wave method for measuring the time taken by the radar signal to travel from the source to the surface of the tank contents and back again. This gives it an unrivalled accuracy for this type of application of better than +/- 5mm, according to Wallberg.
Saab Rosemount claims the STaR system offers big savings during operation over alternative systems, due to its high accuracy and reliability, and the fact that it only requires calibration for the factory acceptance test. Savings also arise from the relatively low maintenance requirement. In addition, the system demands fewer deck installations, fewer tank penetrations and less cabling, bringing substantial cost savings during installation at the yard. Compared with skid-mounted systems, for example, the STaR system provides an economy of $500,000, and a saving of up to 50 sq m in footprint as well as weight.
A key part of the STaR system is the tank gauge unit, in which three functions - level gauging, high level and overfill alarm systems - are integrated in one unit.
The radar technology incorporates a large diameter, high-sensitivity parabolic antenna. The radar waves take the form of a narrow beam which offers high reliability under demanding conditions such as waves, vapors, deep and narrow tanks and low-reflective cargo surfaces. Accuracy is unaffected by cargo composition, density or temperature, from -163°C, as in the case of LNG cargoes, to 250°C.
The non-intrusive system is highly reliable, Wallberg adds. It has no moving parts when installed inside the tank, and all the electronics are outside the tank, making it easy to replace a component in the event of a malfunction.
The Saab TankRadar CTMS system is also suited to the demands of level gauging aboard LNG carriers. In such an environment, not only must the system operate reliably at -163°C - the temperature required for storing the gas in liquid form at normal pressure - but it must also provide accurate and reliable custody transfer measurement as the basis for establishing accounts payable. It must remain up and running all the time the vessel is in operation.
The CTMS system, which can be used with either membrane or Moss type LNG tanks, includes a bottom absorber, a patented method which provides accurate low level measurement when the tank is almost empty.
In addition to the tank gauging system, Saab Rosemount Marine supplies the STaR Service Display system, which provides both monitoring and service functions. In monitoring mode it gives access to all available tank data, including ullage, vapor pressure and temperature. In service mode it can be used to carry out service, verify values and run health checks and diagnostics. If any part of the system goes down, STaR Service Display can be used to restart it.
For more information contact Jan Wallberg, Saab Rosemount Marine. Tel +46 31 337 0393, fax +46 3125 3022,[email protected], www.saabrosemount.com