Within normal distribution activities, diesel and jet fuel quality procedures require fuel to be settled for at least three hours per metre height or 24 hours (whichever is less). This requirement is intended to prevent the shipment of product containing dirt and water that would settle out in a 24-hour period. However, free water and particulate often settle in less than 24 hours, furthermore, some sites may be constrained in the volume of tankage available to store product meaning that settling periods impact upon the operation or further storage tanks are required to be constructed.
Aramco conducted a trial using particle counting technology and water content test methods to establish a procedure that identifies the exact time frame where a tank can be released from settling. Utilising this procedure will ensure that settling time is dictated by actual particulate and water test results rather than an estimated time.
The proposed procedures are as follows:
For both direct and indirect airport jet fuel delivery tanks, a reduced settling time may be applied, as a minimum this shall include the following tests/results:
An Upper, Middle and Lower sample from the tank, each being tested to confirm water and particulate content requirements are met as follows:
• A total water limit of 100 ppm using ASTM D6304 Karl Fischer, or
• A free water limit of 30 ppm max using a Chemical Water Detector, and
• ASTM D5452 Gravimetric with a limit of 1.0 mg/l, or
• Automatic particle Counting ISO Code of: – 19 Max for 4 micron channel count
– 17 Max for 6 micron channel count
– 14 Max for 14 micron channel count
– 13 Max for 30 micron channel count
For diesel fuel delivery tanks, a reduced settling time may apply, as a minimum this shall include the following tests/results: Automatic particle counting ISO Code of: – 19 Max for 4 micron channel count – 21 Max for 6 micron channel count – 18 Max for 14 micron channel count
The above proposed procedure has been field tested in the multiple distribution facilities and has proven to reduce settling periods significantly, as such there is a very significant cost saving associated with adopting the technology and procedure within Aramco operations, while ensuring that quality product is maintained. Below is a demonstration of the successful trial.
Tank A1 Results (Diesel – 150,000 bbl)
Tank A1 produced a required settling period of 12 hours – medium settling time reduction achieved
Results at Tank A1 showed possible reduction of settling periods ranging from 6 – 18 hours.
Utilising the particle counting technology and water content test methods to establish a procedure that identifies the exact time frame where a tank can be released from settling has been carried out. Utilising this procedure will ensure that settling time is dictated by actual particulate and water test results rather than an estimated time.
The trial results and procedure are further supported by recent industry operating standards changes in the aviation fuel environment, namely the EI 1530 standard which allows use of this exact procedure/protocol.
The above proposed procedure has been field tested in the Distribution Facilities and has proven to reduce settling periods significantly, as such there is a very significant cost saving associated with adopting the technology and procedure within Aramco operations, while ensuring that quality product is maintained.
Potential Cost Avoidance
• Assumption of 57 tanks impacted
• Conservative estimate of reducing the settling time of a single tank by 10 percent (2.5 hour reduction) using this technology will increase its throughput by 10 percent
• 10 percent throughput increase per year = +/- $1 MM cost avoidance per tank per year
Particle counters can provide a rapid quantitative analysis of fuel samples that allows monitoring of fuel cleanliness within a distribution system, utilising this technology in the area of tank settling periods allows the time period required to be significantly reduced. The associated protocol allows a quantitative result to be obtained that can be measured against a specification limit to allow a correct decision to be made in releasing a tank, this method compared with the current method time based (24 hours) offers a significant improvement on current procedures and practices.
Figure 2. Stanhope-Seta AvCount Lite Particle Counter
For more information visit www.aramco.com
