Operation Pluto

Operation Pluto (Pipeline Under the Ocean or Pipeline Underwater Transportation of Oil, also written Operation PLUTO) was an operation by British engineers, oil companies and the British Armed Forces to construct submarine oil pipelines under the English Channel in support of Operation Overlord, the Allied invasion of Normandy during the Second World War.

The British War Office estimated that petrol, oil and lubricants (POL) would account for 60 per cent or more by weight of the supplies required by the expeditionary forces. Pipelines would reduce the reliance on coastal tankers, which could be affected by bad weather, were subject to air attack, and needed to be offloaded into vulnerable storage tanks ashore. A special kind of pipeline was required. Two types were developed: Hais and Hamel. Hais arose from a proposal originated by Clifford Hartley, the chief engineer with the Anglo-Iranian Oil Company, for a flexible pipe with a lead core that could be laid by a cable-layer ship. It was known as Hais after its developers, Hartley-Anglo-Iranian-Siemens, and was tested in December 1942 by running a cable pipeline across the Bristol Channel from Swansea to Watermouth. The design was so successful it was decided to upgrade it from in diameter. Hamel pipe utilised readily available thin mild steel instead of scarce lead, and it had to be laid by special floating drums known as Conundrums. Most of the Hais pipe was manufactured in the United Kingdom, although some came from the United States; all of the Hamel pipe was made in the United Kingdom.

Camouflaged pumping stations were established at Sandown on the Isle of Wight, and at Dungeness on the Kent coast, which were connected to the Avonmouth-Thames pipeline. Two pipeline systems were laid: one, codenamed "Bambi", to Cherbourg and one, codenamed "Dumbo" to Boulogne. Deployment of the former commenced on 12 August 1944. It was not very successful, delivering only between 22 September when the first successful Hais cable pipeline became operational, and 4 October, when the Bambi pipeline project was terminated. The Dumbo system was more successful. A Hais pipeline commenced pumping on 26 October, and remained in action until the end of the war. By December, nine 3-inch and two 2-inch Hamel pipelines and four 3-inch and two 2-inch Hais cable pipelines had been laid, a total of seventeen pipelines. The Dumbo system was shut down on 7 August 1945, by which time the pipelines had carried of petrol. The Pluto pipelines were responsible for about 8 per cent of the deliveries of petroleum products from the United Kingdom to the Allied Expeditionary Force in North West Europe.

Background

In early April 1942, the Chief of Combined Operations, Vice-Admiral Lord Louis Mountbatten, approached the Secretary for Petroleum, Geoffrey Lloyd, and asked if an oil pipeline could be laid across the English Channel. Mountbatten was tasked with planning the Allied invasion of German-occupied Europe, and had concerns about the supply of petroleum products, since it was considered unlikely that a port with oil reception facilities could be quickly secured. The British War Office estimated that 60 per cent or more by weight of the supplies of the expeditionary forces would consist of petrol, oil and lubricants (POL). In the initial stages of the assault, packaged fuel would be supplied in jerricans and drums. To supply the twenty million jerricans required, an entire American manufacturing plant was shipped to the London area, where it was operated by the Magnatex firm under the supervision of the Ministry of Supply. By 1944, a stockpile of of packaged petrol and diesel fuel had been accumulated in the UK.

After the first few days of the invasion, it was hoped that petroleum could be supplied in bulk. Pipelines were not the sole or even the principal means by which Combined Operations was contemplating supplying bulk petroleum; it intended to rely primarily on small shallow-draught coastal tankers, of which thirty were under construction. American "Y" tankers began arriving in the UK in the spring of 1944. In 1943, the British also initiated a programme to construct Channel tankers (Chants), but only 37 were completed by May 1944. It was hoped that petroleum products might also be supplied by ocean-going T2 tankers lying offshore through ship-to-shore pipelines. The project to develop these pipelines was codenamed Operation Tombola, and the pipelines themselves became known as Tombolas. The submarine pipeline had sufficient advantages to make it worthwhile to explore as a backup means of supply. Submarine pipelines were less susceptible to enemy air attack and the frequently stormy English Channel weather, and their use would reduce the forces' dependency on vulnerable storage tanks ashore.

Lloyd consulted his expert advisors: Brigadier Sir Donald Banks, the director-general of the Petroleum Warfare Department; Sir , a former director of the Anglo-Iranian Oil Company and the oil advisor to the Fourth Sea Lord; and George Martin Lees, an eminent geologist. At the time, submarine pipelines were in use in ports and over short distances, but no pipeline had ever been laid across such a great distance or under the currents and tidal conditions found in the English Channel. Moreover, to minimise interference by the enemy and the effect of the tides, the entire pipeline would have to be laid in a single night. They regarded the proposal as infeasible using any known method of construction of pipelines or more in diameter.

The Chief Engineer of Anglo-Iranian, Clifford Hartley, was visiting the Petroleum Warfare Department at this time, and he heard about the proposal, and was convinced that it was possible. In the hilly terrain of Iran, Anglo-Iranian had employed a pipeline. Running at , it delivered per day, the equivalent of over 20,000 jerricans. On 15 April he pitched his proposal for a continuous length of pipeline similar to a submarine communications cable without the core and insulation, but with armour to withstand the internal pressure, which could be deployed by a cable-layer ship. Additional capacity could be obtained by laying multiple lines. By using high pressure, the line could carry different kinds of fuel. At low pressure different fuels would mix, but at high pressure they would stay separate. Thus, the pipeline could be used for aviation spirit, and then switched to diesel fuel.

The project was given the codename Pluto, which stood for "pipeline underwater transportation of oil" or "pipeline under the ocean". The operation was placed under the chief of staff to the Supreme Allied Commander, Designate (COSSAC). The G-4 section of the COSSAC staff, which assumed responsibility for Pluto, was headed by British Major General Nevil Brownjohn, with American Colonel F. L. Rash, Colonel Frank M. Albrecht, and Major General Robert W. Crawford successively as his deputy. Royal Navy Captain John Fenwick Hutchings from the Admiralty's Department of Miscellaneous Weapons Development was placed in command of Operation Pluto. By VE-Day his command would consist of several ships, over 100 merchant navy officers and more than 1,000 men.

Development

Hais

Hartley received support for his proposal from the chairman of Anglo-Iranian, Sir William Fraser, who was also the petroleum advisor to the War Office, and from Henry Wright, the managing director of Siemens Brothers. Fraser agreed to pick up the costs of trials, albeit in the hope that the government would subsequently reimburse the company. Siemens Brothers developed the cable in conjunction with the National Physical Laboratory based on their existing undersea telegraph cable. It was known as Hais, from Hartley-Anglo-Iranian-Siemens. The diameter inner pipe, which would carry the petroleum, was made from extruded lead. This was surrounded by a layer of asphalt and paper impregnated with vinylite resin. Steel tape was wound around this to give it strength and flexibility. Around this was a layer of jute tape and asphalt-impregnated paper. Finally, it was covered by a protective layer of fifty galvanised steel wires, and camouflaged canvas cover. The pipe could deliver per day at a pressure of , and withstand an underwater pressure of . The 2-inch size was chosen to keep the weight down; a larger cable would have required a larger ship to deploy it.

A prototype was laid across the River Medway by the Post Office cable ship on 10 May 1942. A pumping test was then carried out using pumps borrowed from the Manchester Ship Canal Company. After two days of pumping, a failure occurred. The cable was pulled up, and the problem was found to have been caused by extrusion of the lead through gaps in the steel tape. Accordingly, the amount of steel tape was increased from two to four layers. At Siemens' suggestion, a second supplier, Henleys, was brought in to increase manufacturing capacity. A second test was carried out in June across the Firth of Clyde, with lengths of pipe manufactured by both Siemens and Henleys. The pipe was laid by the Post Office cable ship ''Iris''. Both functioned successfully. Of the of Hais cable produced for the operation, were made by firms in the United Kingdom, while was manufactured in the United States by four American firms, including Phelps Dodge and the General Electric Company.

Full-scale production of the two-inch pipe was started on 14 August 1942, using steel from the Corby Steelworks, and on 30 October, of it was loaded on board under the command of Commander Henry Treby-Heale, which was to be used as a full-scale rehearsal of Operation Pluto. This trial occurred on 29 December 1942. A 30-mile length was laid across the Bristol Channel in rough weather at a rate of with the shore ends being connected at Swansea and Ilfracombe. The sturdiness of the cable pipe was further tested when two German bombs were dropped on Swansea from the cable. Later a ship's anchor dragged the cable pipe, but ''Holdfast'' was able to locate and repair the damage. To prove the reliability of the cable pipe, pumping operations were carried out continuously, first at the original design pressure of , and then at , with of fuel delivered per day.

The trial was sufficiently successful that it was decided to develop -diameter pipe. This reduced the number of pipelines required to pump the same volume of petrol, as each 3-inch pipe had more than twice the capacity of the 2-inch pipe. A merchant ship, HMS ''Algerian'' was acquired, and converted to carry of 3-inch cable pipe. Two more, and (later renamed ''Empire Baffin'' and ''Empire Ridley'' respectively), could each handle of 3-inch pipe weighing approximately . Anglo-Iranian Oil personnel supervised the erection of pumping equipment by the Royal Army Service Corps (RASC), Pioneer Corps and Royal Engineers personnel, and a RASC bulk petroleum company was specially trained to operate them. A Port of London Authority factory at Tilbury was requisitioned and converted into a cable pipe factory where of cable pipe per day was tested, welded into lengths and stored.

Hamel

Lead was in short supply, so the Petroleum Warfare Department decided to seek an alternative that made use of cheaper and more readily available materials as a backup system to Hais, which was itself a backup system. Bernard J. Ellis, the chief engineer of the Burmah Oil Company, was convinced that a flexible pipeline could be built from mild steel, which was more readily available than lead. His pipe was in diameter, with walls. The prototype was fabricated in segments by J & E Hall, a firm better known as a manufacturer of refrigeration equipment. The segments were made to be flash welded together. Normally welded pipe gave trouble due to rings of residue that formed around each weld. Ellis designed a special broaching tool to remove the metal swarf. Ellis teamed with H. A. Hammick, the chief engineer of Iraq Petroleum Company, and the pipe became known as 'Hamel' after their surnames, although after the war Ellis successfully asserted his claim to be recognised as the sole inventor.

Unlike Hais, Hamel pipe was too stiff to be coiled in a ship's hold, as it could not withstand the twist along the longitudinal axis that came with each turn of the coil. The Petroleum Warfare Department proposed that it be wound around a buoyant steel drum that could be towed by tugs or fitted on a Hopper barge. The resulting steel drum was long and in diameter, and was known as a "Conun" or "Conundrum". Tests were carried out in the Froude tank at the National Physical Laboratory to verify that Conundrums could be towed at speed without yawing.

Stewarts & Lloyds undertook to design, construct and operate two factories at Tilbury where lengths of pipe were welded together into segments. Six Conundrums were constructed at a cost of £30,000 apiece, and named 1 through 6. A Conundrum was towed to a special dock where it was held by two steel arms. A sprocket chain driven by an electric motor rotated the Conundrum while pipe was wound around it. At the end of each segment, the next was welded, the swarf was cleaned out, and the process continued until the Conundrum held of pipe. An Admiralty hopper barge named ''W.24'' was converted to carry a Conundrum, and named HMS ''Persephone''. In testing it successfully laid a dozen Hamel pipes across the Solent to the Isle of Wight. It was not known how long the Hamel pipe would last, but it was assumed to be about six weeks. Fluorescein dye was added to the fuel to allow patrol aircraft to detect leaks. In view of this success, it was decided to utilise both Hais and Hamel.

Pumping stations

In the spring of 1943, the Petroleum Warfare Department selected sites for the pumping stations. One was established at Sandown on the Isle of Wight, and another at Dungeness on the Kent coast. Construction was carried out at night and in secret, and equipment was carried in under tarpaulins. The pumping stations and storage tanks were camouflaged to look like villas, seaside cottages, old forts, amusement parks and other innocuous features. Strict instructions were issued that neither "Petroleum Warfare Department" nor its initials should appear on any letter or package. The locations were erased from maps. Lorry drivers conducting deliveries had to phone from a public phone booth for instructions.

Each pumping station was equipped with thirty diesel-powered reciprocating pumps with a capacity of per day, and four large Byron Jackson Company electric centrifugal pumps capable of per day, which worked out to at . Both stations were fed from the Avonmouth-Thames pipeline, which had a capacity of per month. A branch line was constructed connecting Dungeness with its eastern terminal at Walton-on-Thames. Sandown was connected to the system through a link between the Isle of Wight and Fawley Refinery. The pipeline connections to Pluto were completed by March 1944.

The corresponding sites in France were selected in June 1943. Sandown would be connected to the port of Cherbourg, a distance of over . Dungeness would be connected to the port of Ambleteuse. In keeping with the Disney theme suggested by Pluto, the former was codenamed "Bambi" and the latter "Dumbo". Thames barges were converted to handle connecting the cable at the shore ends, where the waters were too shallow for the ships to operate.

As part of the Operation Overlord deception operation known as Operation Fortitude, a fake oil dock was created at Dover. The architect Basil Spence was called upon to design it. Constructed from camouflaged scaffolding, fibreboard and old sewage pipe, the fake facility spanned and included fake versions of pipelines, storage tanks, jetties, vehicle parks and antiaircraft emplacements. Wind machines were used to create clouds of dust to simulate activity, and the site was guarded by the military police. At night it was obscured by a smoke screen. German aircraft were allowed to overfly the facility, but only above , where high-resolution imagery was not possible. The fake facility was inspected by King George VI, and the Supreme Allied Commander, General Dwight D. Eisenhower and his ground forces commander, General Sir Bernard Montgomery spoke to the "workers".

Placement

Bambi

According to the original Operation Overlord plan, Cherbourg was supposed to be captured within eight days of D-Day (D+8) and, despite the expectation that the Germans would carry out systematic demolitions, be opened within three days. Pipe laying was to commence four days later, with the Bambi system fully operational by D+75 (seventy-five days after D-Day). The discovery of an additional German division in the vicinity in May led to the expected capture being pushed back ten days from D+8 to D+18. In the event, the port of Cherbourg was captured on 27 June (D+21), and due to the extensive damage the first POL tanker did not discharge there until 25 July (D+49). In the meantime, fuel was supplied through the small port of Port-en-Bessin by coastal tankers, and from ocean-going tankers using two Tombola lines at Port-en-Bessin for the British and five at Sainte-Honorine-des-Pertes for the Americans. The Tombola lines had a tendency to break, and the Chants fared poorly in the rough weather of the English Channel. By 28 July sixteen of them were laid up for repairs at a special tanker repair facility that had been established at Hamble-le-Rice.

Consideration was given to cancelling Pluto, but under the circumstances it was decided to proceed. Time was wasted in deciding whether to terminate the line inside or outside the harbour; eventually the latter was chosen. The first Hais pipeline was laid by HMS ''Latimer'' in just ten hours on 12 August 1944, but the pipeline failed when an escorting destroyer caught it with its anchor and damaged it beyond repair. A second effort was made by HMS ''Sancroft'' two days later. This too failed when the pipe became wrapped around the propeller of the support ship, HMS ''Algerian''. An attempt to lay Hamel pipe instead failed on 27 August when it was discovered that tons of barnacles had attached themselves to the bottom of HMS ''Conundrum 1'', thereby preventing it from rotating. The barnacles were scraped off, and another attempt was made a few days later, but the pipeline broke about out.

The expert technicians had been able to lay pipelines across the Bristol Channel and the Solent under the supervision of the designers, but it was another matter for the naval laying parties to achieve the same degree of proficiency under wartime conditions and across the much wider English Channel. Sir Donald Banks wrote: "The technique of cable laying had been mastered but we were not yet sufficiently versed in the practice of connecting the shore ends, nor in effecting repairs to the undersea leaks which were caused fairly close inshore through these faulty concluding operations."

Finally, on 22 September a Hais cable was laid that worked, delivering per day. This was followed on 29 September by the successful installation of a Hamel cable by HMS ''Conundrum 2''. However, on 3 October when the pressure was increased from to augment the amount of fuel pumped, both pipelines failed: the Hais due to a faulty coupling, and the Hamel when it encountered a sharp edge on the ocean floor. Operation Bambi was terminated the following day. Only about () of fuel had been transferred.

Dumbo

Meanwhile, the port of Rouen had been captured on 30 August, and Le Havre on 12 September. Le Havre was badly damaged in the fighting and by demolitions. Rouen, an inland port up the Seine River, was in better shape, with its quays largely intact, although demolitions had been carried out and the river channel to it was blocked by mines and sunken vessels. Even when it was cleared the channel from Le Havre was shallow, but coastal tankers carrying POL from the UK were able to navigate it and discharge in Rouen. Boulogne was captured on 22 September, and the port was opened on 22 October.

A Hais pipeline was laid by HMS ''Sancroft'', which commenced pumping on 26 October, and remained in action until the end of the war. Lines were run to a beach in the outer harbour of Boulogne, distant across the Strait of Dover, instead of Ambleteuse as originally planned because the beach at the latter was heavily mined. This involved a longer distance and a more difficult approach, but cable-laying techniques had been refined. The ends of the cable were dropped just offshore and picked up by the barges for connection to the shore. The Hamel pipe gave more trouble, but after some trial and error, it was laid with sections of Hais pipe at each end. Boulogne also had poor railway facilities, so the pipeline was extended to Calais where better railway connections were available to transport the fuel. This extension was completed in November.

By December, nine 3-inch and two 2-inch Hamel pipelines and four 3-inch and two 2-inch Hais cable pipelines had been laid, a total of 17 pipelines, and Dumbo was providing of petrol per day. Not one of the Hais cable pipelines broke, and the mean time between repairs of the Hamel pipelines varied between 52 and 112 days, with 68 days being the average. They could not be run at the intended pressure, so they carried only petrol, and plans for the pipelines to deliver aviation spirit as well were discarded.

In December there was reconsideration of whether to continue with Operation Pluto. By this time Antwerp was unloading an ocean-going tanker a day, and coastal tankers were delivering per day to Ostend, and a similar amount to Rouen. On the other hand, only Antwerp and Cherbourg were capable of handling the large tankers, but Antwerp was under attack from V-1 flying bombs and V-2 rockets, and it was considered inadvisable for it handle more than one tanker at a time. As for the coastal tankers, they were in demand for service in the Far East. It was therefore decided to continue with Operation Pluto.

As the fighting moved on to Germany, Dumbo was connected to an inland pipeline system that was extended from Boulogne to Antwerp, Eindhoven

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