The Welding Institute

The Welding Institute and ‘Operation PLUTO’

9 Feb 2023 11:00 AM | Anonymous

Recent research into The Welding Institute has unearthed some previously unidentified, yet interesting connections between the D-Day landings, the Institute, and the start of what became the entire modern offshore oil and gas industry.


To set the scene, we need to go back to 1942 when The Welding Institute was known as The Institute of Welding (see our ‘Celebrating 100 Years of The Welding Institute’ article for more details on how the Institute developed over the years) and plans were beginning for what would become ‘Operation Overlord,’ the Allied military operation that began on 6 June 1944 (D-Day) and led to the successful invasion of German-occupied Western Europe during World War II.

D-Day itself saw 160,000 troops crossing the English Channel and landing on the beaches of Normandy, soon to be followed by more Allied troops and vehicles in the following days and weeks. In order to maintain the momentum of the invasion following the first landing, it was necessary to keep forces supplied with fuel for their vehicles.

Supply and Demand?

Coastal tankers could have been used, but they can be delayed by poor weather, are exposed to attack from the air, and need to be offloaded onshore into vulnerable storage tanks.

As the British War Office estimated lubricants, oil and petrol would account for over 60% of the weight of supplies needed by the expeditionary forces, subsea pipelines were seen as the best solution.

At this point in the 1940s, submarine pipelines had been used by ports and over short distances, but they had never before been deployed in the tidal conditions and over the distances required to span the English Channel. To add to the challenge, the entire pipeline needed to be deployed in a single night so as to reduce the possibility of enemy or tidal interference as the pipes were laid.

Creating and deploying these pipelines quickly and effectively was the challenge to be met by Operation PLUTO (Pipeline Under The Ocean or Pipeline Underwater Transportation of Oil).

An engineer visiting the Petroleum Warfare Department at the time proposed the use of a single, continuous length of armoured pipeline that was similar to a subsea communications cable with the core and insulation removed, yet able to withstand high internal pressures. The use of additional lines would increase capacity and it was felt using high pressures would allow for different types of fuel to be carried.

‘Hais’ and ‘Hamel’

Operation PLUTO led to the creation of two different pipeline designs, ‘Hais’ and ‘Hamel,’ named for their inventors.

The Hais solution used an existing undersea telegraph cable design to create a 2-inch pipe made from extruded lead. The lead was surrounded by a layer of asphalt and paper that had been impregnated with vinylite resin. This layer was covered in steel tape, followed by a layer of jute tape and asphalt impregnated paper, before a final protective layer of 50 galvanised steel wires and a camouflaged canvas cover. Several tests were carried out on the Hais pipe and it was decided to increase the diameter to 3-inches, thereby doubling the amount of petrol that could be pumped compared to the 2-inch pipe. This pipe could be coiled in the hull of a pipe-laying ship ready for deployment, but because lead was in short supply, an alternative pipe was sought that used cheaper and more readily-available materials.

The chief engineer of the Burmah Oil Company, Bernard J. Ellis, proposed the use of mild steel to create an alternative, flexible 3.5-inch diameter pipe and teamed up with the Iraq Petroleum Company’s chief engineer, H. A. Hammick, to create the ‘Hamel’ pipe.

Unlike the Hais pipe, the Hamel pipe was too stiff to be coiled up and deployed by ship, so, instead, it was wound around a buoyant steel drum (so it would not twist along the longitudinal axis) called a ‘Conundrum’ (or ‘Conun’).

It is this conundrum-deployed Hamel pipe that has ties to the Institute of Welding, as it was joined using flash butt welding, with Stewarts and Lloyds supplying 40-foot (12 metre) lengths of pipe and designing, constructing and operating two factories at Tilbury to weld them into 4,000 foot (1,200 metre) long segments.

Research Expertise and The Institute of Welding

The creation of the Hamel pipe has its roots in research work undertaken by a committee of The Institute of Welding started in 1938. This research assessed flash butt welding, electric arc welding and oxy-acetylene welding as methods for joining pipes, and was reported in a paper on ‘Pressure Pipe Welding’ mentioned in the Institute’s quarterly transactions in 1941. This was quickly followed by two more papers that became the important underpinning work upon which the Hamel pipe solution was built.

But this was not just a fortunate coincidence, as the Institute of Welding acknowledged Stewarts and Lloyds in relation to work to develop flash butt welding. Both flash butt welding and oxy-acetylene welding can also clearly be seen in a film from the time about the development of the Hamel pipe, with both techniques researched having been assessed for pipe welding by the Institute.

It is clear that The Institute of Welding was involved in the core of early development work (nowadays covered by Technology Readiness Levels 3-6), with this important research enabling Stewarts and Lloyds to manufacture Operation PLUTO’s Hamel pipelines.

Operation PLUTO Pumping Stations

Camouflaged pumping stations were established at Sandown on the Isle of Wight and at Dungeness on the Kent coast. These pumping stations were disguised as seaside villas and cottages, old forts and amusement parks, while lorry drivers were told to call from public phone boxes to receive their delivery instructions.

At the other end of the pipelines, the Sandown pipe was to be connected to the port at Cherbourg and Dungeness was to be connected to the port at Ambleteuse (later changed to Boulogne). Maintaining the Walt Disney theme of Operation PLUTO, the Sandown pipeline was codenamed ‘Bambi’ and the Dungeness pipeline, ‘Dumbo.’ Meanwhile, a fake oil dock was built across 3 acres at Dover, codenamed Operation Fortitude and even ‘inspected’ by King George VI, and the Supreme Allied Commander, General Dwight D. Eisenhower as well as ground forces commander, General Sir Bernard Montgomery.

Deployment and Operation

The deployment of Bambi began on 12 August 1944, with the Hais pipe being deployed first, followed by a Hamel pipe on 27 August. However, both of these first attempts suffered failures. Finally, on 22 September, a Hais pipe was successfully deployed, delivering 56,000 imperial gallons (250,000 litres) per day. On 29 September the Hamel pipe solution was successfully installed, but an increase in pressure from 50 to 70 bar on 3 October caused both pipelines to fail – Hais due to a faulty coupling and Hamel due to a sharp edge on the ocean floor. Bambi was cancelled the next day, having delivered just 935,000 imperial gallons (4,250,000 litres) of fuel.

Dumbo was more successful, with a Hais line deployed and beginning operation on 26 October 1944, where it remained in operation until the end of the war. The Hamel pipe was adapted with the Hais solution added at each end and the pipeline was extended to reach Calais by November so as to take advantage of better railway connections there. By December, nine 3-inch and two 2-inch Hamel pipelines along with four 3-inch and two 2-inch Hais pipelines had been laid, providing 1,300 tons of petrol per day. As was expected, the Hamel pipelines required some repairs during service but the Hais pipelines did not break during service, although plans to increase the pressure to carry aviation spirit as well were scrapped. Dumbo’s 17 pipelines were finally shut down on 7 August 1945, having carried 180 million imperial gallons (820 million litres) of petrol.

In total, Operation PLUTO successfully delivered around 8% of petroleum products from the UK to the Allied forces in North West Europe at an estimated cost of £4,428,000.

85% of the pipeline was salvaged and scrapped between September 1946 and October 1949, the value of the recovered lead and steel (not to mention 75,000 imperial gallons of fuel still in the pipelines) exceeded the cost of recovery at an estimated value of £400,000.


There has been some debate among historians as to the value of Operation PLUTO for the war effort, especially the less-than-successful Bambi pipeline.

However, the impact of the work undertaken for the operation can be felt reverberating down the decades since, not least with the establishment of pipe welding, pipe coiling and large scale subsea pipeline laying.

These core technologies, developed in part due to the work of The Institute of Welding, enabled offshore oil and gas exploitation, which became a cornerstone of the work of the Institute and TWI in the 1960s and 70s.

While the focus of those involved in Operation PLUTO was to help win World War II, they could not have possibly have known that there innovative work would lead to future peacetime applications that progressed the oil and gas industry over the coming years.

This video, produced by Stewarts and Lloyds at the time, clearly shows the testing and production of the Hamel pipeline solution that the Institute was influential in developing.

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