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PLUTO (Pipe-lines Under the Ocean)

Operation Pluto (Pipe-Lines Under The Ocean) was a World War II operation by British scientists, oil companies and armed forces to construct undersea oil pipelines under the English Channel between England and France.

The scheme was developed by Arthur Hartley, chief engineer with the Anglo-Iranian Oil Company. Allied forces on the European continent required a tremendous amount of fuel. Pipelines were considered necessary to relieve dependence on oil tankers, which could be slowed by bad weather, were susceptible to German submarines, and were also needed in the Pacific War. Geoffrey William Lloyd, the Minister for Petroleum, met Admiral Mountbatten, Chief of Combined Operations, whose area this was, in 1942 and then the Chairman of Anglo-Iranian. Hartley's idea of using adapted submarine telephone cable was adopted.

Two types of pipeline were developed: the flexible 'HAIS' (Hartley-Anglo-Iranian-Siemens) pipe with a 3 inch (75 mm) diameter lead core, weighing around 55 long tons per nautical mile (30 t/km), was essentially a development by Siemens Brothers (in conjunction with the National Physical Laboratory) of their existing undersea telegraph cables. The second type was a less flexible steel pipe of similar diameter, developed by engineers from the Iraq Petroleum Company and the Burmah Oil Company, known as 'HAMEL' from the contraction of the two chief engineers, HA Hammick and BJ Ellis. It was discovered in testing that the 'HAMEL' pipe was best used with final sections of 'HAIS' pipe each end. Because of the rigidity of the 'HAMEL' pipe, a special apparatus code-named The Conundrum was developed to lay the pipe.

The first prototypes were tested, across the River Medway, in May 1942 and in deep water across the Firth of Clyde, a month later, before going into production. Due to capacity limitations in the UK, some 'HAIS' pipeline, was manufactured in the United States.

In June 1942 the Post Office cable ship, Iris, laid lengths of both Siemens' and Henleys' cable in the Clyde. Both pipelines were completely successful and the Pipeline Under the Ocean, PLUTO, was formally brought into the plans for the invasion of Europe. The project was deemed 'strategically important, tactically adventurous, and, from the industrial point of view, strenuous'.

The Clyde trials showed that it was necessary to maintain an internal pressure of about 7 bar (100 pounds/in') in the pipeline at all times, even during manufacture. In addition, existing cable ships were not large enough, nor were their loading and laying gear sufficiently powerful and robust. Consequently, a number of merchant ships were converted to pipe-laying by stripping the interiors and building in large cylindrical steel tanks, fitting special hauling gear and suitable sheaves and guides. It was to the specialised Johnson and Phillips company, that the Petroleum Warfare Department turned for special gear to handle and lay the pipe. As the pipe could not be bent to a smaller radius than five feet; a new haul-off drum of ten-foot diameter and fleeting ring, together with roller type bow and stern gear, were produced, and the final equipment fitted to HMS Holdfast.

Full-scale production of the two-inch pipe was started on the 14th August 1942, using steel from the Corby steel works, and six weeks later, on the 30th October a thirty-mile length was loaded on board HMS Holdfast under the command of Commander Treby-Heale OBE, RNR, which was to be used as a full-scale rehearsal of Operation PLUTO. This trial took place between 26 December and 30 December, the thirty-mile length being laid across the Bristol Channel, in very bad and rough weather, and the shore ends being connected up at Swansea and Ilfracombe. Those on board to monitor the test were Mr Hartley (Anglo-Iranian Oil), Mr Tombs (Anglo-Iranian Oil), Mr Colby (Iraq Petroleum), Mr Betson (Post Office), Commander Hardy (Admiralty) and Mr Whitehead OBE (Johnson and Phillips), who had designed the pipe handling equipment.


The rehearsal was a success, so much so that a three-inch (76 mm) diameter pipe rather than two was considered. This reduced the number of pipelines needed to pump the planned volume of petrol across the channel. The change necessitated further alterations and additions to the pipeline handling gear. Two further ships, HMS Sancroft and HMS Latimer, were equipped with handling gear, both of which could handle 100 miles (160 km) of three-inch (76 mm) pipe weighing approximately 6,000 tons.

The pipeline across the Bristol Channel was used to supply parts of Devon and Cornwall for the next year, during which time RASC and RE army personnel were trained to petrol pumping equipment in readiness for the invasion of Europe. Johnson and Phillips were asked to provide storage sites in the East India and Surrey Commercial Docks. These sites were obtained and equipped with tubular steel bridges with overhead hauling gear erected in such a position that the pipe could be taken from a ship's tanks.

After full-scale testing of a 83 km (45 nautical mile) 'HAIS' pipe between Swansea in Wales and Watermouth in North Devon, the first line to France was laid on August 12, 1944, over the 130 km (70 nautical miles) from Shanklin Chine on the Isle of Wight through the English Channel to Cherbourg. A further 'HAIS' pipe and two 'HAMELs' followed. As the fighting moved closer to Germany, 17 other lines (11 'HAIS' and 6 'HAMEL') were laid from Dungeness to Ambleteuse in the Pas-de-Calais.

The PLUTO Pipelines were linked to pumping stations on the English coast, housed in various inconspicuous buildings including cottages and garages. Though uninhabited, these were intended to cloak the real purpose of the buildings. The Pluto Cottage at Dungeness, a pumping station built to look like a small house, is now a Bed and Breakfast. In England, the PLUTO pipelines were supplied by a 1,609 km (1,000 mile) network of pipelines (constructed at night to prevent detection by aerial reconnaissance) to transport fuel from ports including Liverpool and Bristol. In Europe, the pipelines were extended as the troops moved forward and eventually reached as far as the Rhine.

In January 1945, 305 tonnes (300 long tons) of fuel was pumped to France per day, which increased tenfold to 3,048 tonnes (3,000 long tons) per day in March, and eventually to 4,000 tons (almost 1,000,000 Imperial gallons) per day. In total, over 781 000 m2 (equal to a cube with 92 meter long sides or over 172 million imperial gallons) of petrol had been pumped to the Allied forces in Europe by VE day, providing a critical supply of fuel until a more permanent arrangement was made, although the pipeline remained in operation for some time after.

Dumbo was the codename given to the pipeline that ran across Romney Marsh to Dungeness and then across the English Channel to France. The route of the pipeline can be traced in various places on Romney Marsh. Where the pipeline crossed water drainage ditches, it ran above ground in a concrete case. Several of these can still be found. Along with the Mulberry Harbours that were constructed immediately after D-Day, Operation Pluto is considered one of history's greatest feats of military engineering. The pipelines are also the forerunners of all flexible pipes used in the development of offshore oil fields.


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