In 1936 the RAF held small amounts of fuel on its airfields and only 8,000 tons of fuel in reserve with commercial companies. To put this figure in context, 8,000 tons was the daily usage by RAF and USAAF planes operating out of GB at peak during WW2. The RN had large amounts of storage but it was all in densely packed above ground tank farms located close to the main ports. Commercial storage was also in closely packed above ground tanks. In July 1936 the Air Raid Precautions Department of the Home Office concluded that ‘it is perfectly plain that if a determined attack was made on these installations nothing could save them’. It also concluded that similar petroleum storage facilities on the Humber and along Southampton Water were equally vulnerable.

Starting in 1936 plans were put forward for the building of large volumes of protected tank farms both for the military and for civil storage. Initially 90,000 tons was planned in 1936 for the RAF and then this was raised to 290,000 tons. Following Munich this was increased to 436,000 tons and then 850,000 tons. By 1943 two million tons of storage had been constructed for the RAF.

Although there were a number of different types of storage tanks constructed, the most common and long lasting was designated the C2 design. I have a copy of a 1938 design drawing for one of them as well as photos of their construction.

The C2 design was that of a steel lining of a concrete chamber, and the experience of over 70 years of operation has confirmed the wisdom of the original selection. It was a vertical, cylindrical, reinforced concrete chamber which was semi-buried; typically half of the tank was below ground and half above ground. It contained, in the form of a lining, a mild steel all-welded open-top tank. The steel tank was built on a concrete foundation, and when completed was hydrostatically tested by filling it with water and then checking for leaks. The concrete chamber and roof were built to withstand the side and overhead loads, the roof slab being supported on 45 columns within the tank. The tank was to prove to be relatively cheap to build and excellent in service, fulfilling all the requirements of protected storage. The tank was finally mounded over with the spoil from the excavation both making it better protected against air attack and also less visible from the air.

The tanks were built with ¾ inch thick bottom plates; the sides were made up of 1inch shell plates welded together. A girder kept the tank cylindrical and helped it withstand the stresses during the period before the concrete walls were cast around it and when the tank was under hydrostatic test. Investigation showed that 6 feet 6 inch x 20 feet was the optimum size for the floor plates that made up the 118 feet diameter tank bottom. As the tank bottom had to support the tank columns that held up the concrete roof slab, it needed to be as flat as possible. It was, however, no easy matter to keep an area of 10,000 square feet flat and various welding sequences were tried until this was achieved. Most of the tank bottoms were laid directly and welded on the concrete foundation and hydrostatically tested after the shell plates had been erected on the sides of the tanks.

The concrete foundations were designed to be 125 feet 6 inch in diameter. The steel walls were utilised as shuttering on the inside for the concrete wall but wooden shuttering had to be constructed for the outer face. The shell walls were reinforced with steel rods inserted into the shuttering before the concrete was poured in. The walls were fixed to the floor by means of steel rods already set in the concrete foundation and pointing up into the wall shuttering. The concrete roof was placed on top of the walls and the tank columns and again shuttering was utilised to form the shape for the roof. The first tanks were constructed with tubular columns but these were later replaced with built-up welded channel sections which were made up and welded in situ.

In a paper written after the war M.Noone: Wartime Underground Oil Storage in Britain he noted that “possibly the most remarkable thing about the whole programme was the reliance upon welding. The writer is not aware of an installation of underground tanks which used riveting as the means of joining the shell plates together. The fact that these underground tanks have given remarkably good service over a number of years has added materially to the confidence of the engineering industry in its use and application of electric arc welding.”

Tim

Tim of Aclea wrote:

The RN had large amounts of storage but it was all in densely packed above ground tank farms located close to the main ports.  Commercial storage was also in closely packed above ground tanks.

Do we know if C2 tanks were also used by the RN or were used outside the UK? I'm aware that the Royal Australian Navy had storage tanks at Cairns in Queensland among other places. I’ve never been to Australia but Mrs V was there a few years ago. Although probably not C2 in design (the roofs are sloping) the oil storage tanks in Cairns have since been turned into an arts centre attached to the botanic gardens there. Apparently the pump house now houses the administration offices. The tanks were constructed by the RAN in the 1940s and were in use until the 1980s although the site had been a fuel depot since the 1880s. You can read more about the site here:

Tanks Art Centre - History

And here’s a remarkable picture of one of the heavily reinforced tanks now serving as an art gallery:

Tanks Art Centre - Tank 4

And this tank is now used as a theatre:

Tanks Art Centre - Tank 5

Not mentioned on that site, but according to Mrs V, someone told her that after the war one of the tanks had been switched to storing molasses but that that sweet, sticky substance turned out to be much more damaging to the structure of the tank than petroleum. I have my doubts on that story because the decontamination costs for conversion from fuel to molasses must surely have been prohibitive. It could be true though.

RN tank farms would almost entirely be used for FFO - Furnace Fuel Oil. That's much less inflammable than petrol, and they always hated carrying aviation spirit (RN storage for that was much more heavily protected than USN practice - the time taken to modify the storage in American built escort carriers, and the reduced volume available, was a constant source of tension during WWII. Think HMS Dasher wasn't modified, and was lost to petrol fire andf explosion.)

Electric arc welding had been demonstrated fairly early in the 19th century but it wasn't really of any practical use until the turn of the 20th century when improved electric power sources and coated metal electrodes were developed. Electric arc welding of steel plate was used in the armaments industry and ship-building during WW1, more so in the US than in Britain, but the hulls of most ships were still predominantly rivetted right up to the the 1940s. WW2 however saw widespread adoption of arc welding in munitions and armaments industries ... and increasingly in shipbuilding too. The hulls of mass-produced Liberty ships and tankers were almost entirely welded, which greatly simplified and speeded up their construction.

But then there were a several catastrophic ship losses (initially ascribed to U-boats), the most significant being that, in 1943, of the SS Schenectady, a US-built tanker constructed to a standard design. Luckily she broke apart at her moorings and in shallow water, and so the cause of the failure could be intensively investigated.



The result was the discovery of the phenomenon of ductile-brittle transition which can affect certain ferrous alloys and in particular low carbon steel, which is just the sort of material that ships were usually made of. The problem is that, while the metal will usually deform ductily (ie it will bend), below a particular temperature, which unfortunately is typically around 0°C for mild steel, the metal, if suddenly stressed will behave in a brittle manner (ie it will just snap). It had been generally known that hull plates of ships would sometimes crack across in rough cold seas, but the effect was limited to individual plates, and so while the ship might leak a bit it wouldn't fall apart. But with all-welded hulls the crack could run along the length of the welded seam and so, as with the SS Schenectady, the ship just suddenly snaps in two. The solution was to modify the alloy composition, particularly that of the weld filler metal, so that the critical ductile-brittle transition temperature was reduced to well below anything the ship would ever be likely to encounter, and so the metal would always deform elastically, or even plastically, rather than crack in a brittle manner.

Ductile-brittle transition is a potential problem for welded steel fuel tanks, but in practice, even if made in un-modified mild steel, in use they would rarely experience the disasterous combination of sub-zero temperatures and sudden physical shock (high strain rate). And being a lining backed by concrete, even if they did become cracked rather than dented by an accidental blow (or deliberate bomb strike) the tank as a whole would leak only slowly.

Hi Vizzer, MM and GG

thanks for resurrecting this topic from the grave.  Working for the Oil and Pipelines Agency (OPA), we did not deal with naval storage sites which came under the Admiralty up until shortly before I retired.  However, then the MoD decided in its wisdom to have OPA take over the naval sites of which there were 6 depots (known as Oil Fuel Depots [OFDs]) in the idea of amalgamating all its fuel expertise in one organisation.  However, by then I was only working part time and so had no involvement in the OFDs and they were never treated as part of the GPSS.   

Later when they government decided to sell off the GPSS for £68M and then pay back the Spanish buyer £250M over the next 10 years to use the GPSS, they did not include the OFDs in the sale and so retained part of OPA (most went with the pipeline network) to run the OFDs.  By that time anyway OPA had already lost of its 'expertise' through a new CEO who managed to either make people redundant, cause them to leave or retire, as I did.

What I can tell you about the OFDs is that 2 are very old and have above ground non C2 storage, and 4 are post war.  One of these does have C2 tanks but it was originally built for the GPSS and then later transferred to the Admiralty and 3 use a design similar to the C2 but more modern and also used on some GPSS sites and in Western Europe.

I do not know if the C2 was used outside of the UK during the war but it was a good design and it would seem logical to use it where there was a danger of air attack.

Concerning converting tanks into art facilities, the tanks in Tank Modern, which was originally an oil fired power station and had C2 tanks built into it have been opened up and it is possible to walk into them, I refer to it in my books.

Black oils such as furness oil were at one time stored on the GPSS at one time but the tanks had to be built with in built heating coils and also have their own pipework.  they are not now though and the tanks were either converted to white oils or mothballed.

Although the C2 tanks were welded the pipelines built during the war were not and later had to be relaid because of high leakage from them - also dealt with in my book.

regards

Tim

Vizzer wrote:

Not mentioned on that site, but according to Mrs V, someone told her that after the war one of the tanks had been switched to storing molasses but that that sweet, sticky substance turned out to be much more damaging to the structure of the tank than petroleum. I have my doubts on that story because the decontamination costs for conversion from fuel to molasses must surely have been prohibitive. It could be true though.

A bit off topic but there have been some catastrophic failures of molasses tanks, caused by a variety of reasons although all probably in part because molasses, unlike flammable fuels, was generally considered a benign substance and its storage treated somewhat casually.

The major problem with molasses is its density. Standard practice for all storage tanks, regardless of what they were to contain, would be to fill with water to test for leaks. This also serves as a proof test for pressure as water is denser than oil and considerably denser than volatile spirits such as petrol. Molasses is however denser than water so a test-fill with water does not take the tank to the same stress levels it would encounter in service when filled with molasses. (Typical relative densities are:  molasses 1.42 ; water 1.00 ; fuel oil 0.98 ; diesel fuel 0.83 ; ethanol 0.79 ; petrol 0.75).

The most serious molasses tank failure I’m aware of (there have been several) occurred in Boston, Massachusetts on 15 January 1919. A 50ft tall, 90ft diameter tank containing about 2,300,000 US gal (8,700m³) suddenly burst and collapsed unleashing a wave of molasses 8m high at its peak and moving at about 50 km/h. The wave was of sufficient force to bend the girders of the adjacent elevated railway and tip a railcar off the tracks, and adjacent city blocks were flooded to waist deep in molasses. About 150 people were injured and 21 killed, as well as numerous horses, both by being crushed by debris pushed by the wave, or by drowning/suffocating in the viscous, sticky liquid.

The Boston molasses disaster, before and after:

  

The investigation showed that the tank was constructed poorly and tested insufficiently. The steel used, particularly for the structural hoops, was of insufficient thickness even given the lax standards of the day, and was, like in the case of the SS Schenectady described above, prone to brittle failure - it occurred on a cold January morning - although this risk would not have been understood at the time. The tank had never been water tested prior to going into service and had always leaked, but as it was ‘just’ molasses nobody worried about this and the tank was simply painted brown to mask the tell-tail streaks of leaking fluid, while the local people happily collected the escaping molasses for their own use. Furthermore the tank had only been filled to capacity on just a few occasions during its life but was full on that day (possibly a consequence of the increased demand for molasses by distilleries in the run-up to the imminent prohibition of alcohol in the US - the 18th amendment to the constitution was ratified the following day on 16th January). It was also thought possible that, unlike of course oil, the molasses had started to ferment thereby generating carbon dioxide gas, and as there was no venting system this would have increased the internal pressure.

Vizzer, you comment that cleaning a tank of oil might preclude its subsequent use for molasses, but it would probably not be as difficult to cleaning a tank of molasses for use as fuel storage. The Boston clean-up took weeks using sea-water pumped from the harbour - whose waters turned brown - while on hot days the whole area still smelled of molasses decades later.

I never appreciated the complexities of making storage tanks.  Still as I've mentioned before I was only able to study General Science at my school.

MM mentions the devastation caused by the molasses tank exploding.  My late mother said she'd read a book where someone had been burned by acid in the manufacture of American Pure Lard.  I don't know which book it was.  She said she never bought American Pure Lard (which did used to be on sale in the UK at one time) after reading that.  I can remember hearing something on "the news" many years ago about a nasty event where a tanker carrying some acid was involved in an accident.  I guess the achievements of engineers are taken for granted when everything goes swimmingly and people only raise questions when something goes wrong.

Of course, Tim, by the later 1970s the Admiralty was using very little FFO - the rise of COSAG and COGOG/COGAG systems meant that, to fuel the gas turbines, it was necessary to supply diesel or kerosene type fuels, and, given that, it was advantageous to convert the steam plant to burn that as well. One of the (ludicrous) excuses for not sending the Navy's only hospital ship (HMS Britannia) to the Falklands was that she still burned FFO. I'd speculate that that decision pretty much decided her fate - if you can't use your only hospital ship in time of conflict, it's entering chocolate teapot territory.

Hi George

I am afraid the fuels used by the RN is a bit outside my knowledge area except that I was aware that the FAA used a different spec and less flammable spec for aviation fuel.  As I posted, the GPSS did not supply the RN.  In the draft of my book I initially drafted too much space to the Falklands War, the GPSS did supply the RAF during the war, and, at the suggestion of one of the people commenting on the drafts, drastically cut it down in the published version.  I entirely agree that not sending the Royal Yacht to the Falklands was the cause of it not being replaced.

regards

Tim

After the Buncefield explosion in 2005, not one of our sites I am glad to say, OPA were approached as to whether we could use some of the empty GPSS tanks for storage of the polluted firefighting water - we declined.  The concern with the pollution was not with any unburnt fuel mixed in with it but with some of the chemicals used to create the foam necessary to fight and oil fire.  Buncefield had been on such a scale that the the 'safe' stocks of foaming agent were used up and the authorities had to revert to old and environmentally unsafe stocks.  I was advised, off the record, that the correct thing to have done would have been to just let the fire burn out but that it was politically impossible to have done that.

Tim

A few years ago a fireworks warehouse went up in flames near my neck of the woods.  Of course that wasn't anything in a tank - it was very sad, two people lost their lives.  It may have been a cigarette butt  (but don't take that as gospel).  The warehouse was on an industrial estate adjacent to the Staffordshire & Worcestershire Canal which was recently mentioned on another thread.

In the early 1960s (I'd gone with a couple of friends and the mother of one of them to see Follow that Dream with Elvis) some calor gas containers exploded in a store in my hometown.  Some people on the outskirts of town thought a war had started.  We had to exit the cinema and missed some of the film but did get to see the end.

Is there an ongoing safety issue in the Buncefield area, Tim.  I remember seeing that event on TV news and it did seem a real catastrophe.

LinR

Any site storing large amounts of highly flammable and explosive materials is going to have safety risks but undoubtedly the Buncefield explosion was a massive shock to the whole system and safety methods will have been greatly improved as a result of the investigations into what went wrong.

regards

Tim