Polar Radar for Ice Sheet Measurements

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Special Report: Fuel Oil Transfer At Davis Station

The power at the stations comes from powerhouses which generate power by burning diesel oil. The diesel we use is a very light grade without the waxes found in normal diesel. This is on account of the very low temperatures in which we have to operate - at low temperatures the waxes can separate out and clog filters and so on.

The exercise is simply to transfer fuel from the bulk fuel storage facilities in Hobart to the bulk storage facility at Davis. You might remember me telling you that before we left Hobart the ship moved from Macquarie Wharf where we loaded cargo to Self’s Point for ‘bunkering’. At Self’s Point which is the bulk oil storage facility for Hobart we loaded two types of fuel - ‘bunkers’ a Marine Gas Oil used on the ship for its engines and propulsion, and SAB (Special Antarctic Blend) that is used for powering the station power houses. We loaded 640,000 litres of SAB - you might remember telling you about what that figure means when I told you about the cargo we were carrying on this ship.

So, we set sail with the SAB in special storage tanks on board the ship. When we reached the anchorage point at Davis in the fast ice, our task was of course to transfer it to the bulk storage tanks on the Station. These are located at the top of a low ridge above the station - about two hundred metres from the shore, and we were parked about three kilometres off shore.

The system is basically fairly simple - a hose line from the ship running to the ‘fuel farm’ on the shore. We carried the hose line with us - it is called a ‘lay-flat’ because it is flat when empty. The hose is in 200metre lengths, each length on a spool, ten spools to a big reel. Each spool is just a bit bigger than the width of the hose and around two metres in diameter, the spools are side-by-side like a bunch of stacked coins but on their side. We had two reels, giving us a total of four kilometres of hose, but this special hose is only used to reach the shore line - there it is attached to a fixed system which runs up to the fuel farm.

The lengths of hose are joined together and because of the distance over which we pump, we install a booster pump part way along the line to give an extra push, particularly for the last uphill section. There is also a compressor on the line at the ship end, but I’ll explain its purpose a bit later.

So the whole system comprises - the ship/its storage tanks/its pumps to draw the oil from storage and push it along the line, the compressor set up near the bow of the ship, the hose line running over the surface of the ice all the way to the shore, a booster pump close to the shore end, a fixed pipe (called a Stand Pipe) on the shore and to which the hose line is connected, the fixed hose running to the fuel farm storage tanks. There are of course various gauges and meters at different points in the system.

The hose reels were taken out of the ship and put on to the ice near the front of the ship. The lengths of hose are drawn off the hose reel and dragged across the ice behind a Quad (a four wheel bike). These are laid out in an approximate line nose to tail and then the work team comes along and joins them together. The connections are then tested by blowing compressed air along the line and every joint is thoroughly checked for signs of leakage. Joints are then tightened or parts replaced and the process done again, and again, until all are happy that the line is intact. And only then does pumping start. While the pumping is occurring there were people dedicated to monitoring and watching every stage of the process, including constant patrols by vehicle of every inch of the pipeline looking for any evidence of spill. Pumping rate is monitored regularly at both the ship and fuel farm ends, and tanks are ‘dipped’ regularly to measure the volume transferred.

And when pumping is finished, the next problem - what do you do with the oil that is sitting in 3.5 kilometres of hose line? If the line is 12.5cm in diameter - how much oil is that? Obviously you can’t just let it run out - you might as well save what you can and it is not good to pollute the environment anyway. The answer is you ‘pig’ the line. Eh? Pig? Well, you send a pig down the line to push all the oil in front of it into special storage bins, which can then be taken to the fuel farms and added to the storage tanks. A pig? Not a real one surely, and it would have to be pretty small? Actually it is a firm torpedo-shaped foam rubber gismo which just fits inside the line and is propelled along it by a blast of compressed air - this pushes the excess oil out of the pipe – the process is called ‘purging the line’. In the early days of this kind of technology in the oil industry the lines were a lot bigger and correspondingly the ‘pig’; the early devices were also pink - hence ‘pig’ became the expression. As each length of line is disconnected it is fitted with caps and when rolling up the reel starts, the cap at the ‘far end’ is removed and as the hose is coiled on to the reel any oil still in the line is squeezed out into a special storage tank attached to the end of the hose.

So it is a very careful operation designed to minimise the risk to the environment and it is also a very efficient process - particularly going over the hard sea ice.

How long did it all take? And how much did we pump? Well, the team started laying out the hoses at 1500 Thursday, connections made and checked, pumping commenced 1830 Thursday, pumping stopped at 1545 Friday, the line was pigged and purged, checked and rolled up for stowage back on the ship at 2130 Friday. A total of about 30 hours - and we pumped 630,000 litres of fuel. How long would it take to pump that amount into a car at a gas station - assuming there was enough fuel at the petrol station and you had a big enough car to take it?

So that’s it about fuel pumping - as practiced at Davis. The same principles are applied at other stations but each has its unique time and way of handling the exercise.



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