Operation Pluto - Development

Development

Two types of pipeline were developed: the flexible HAIS 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, and known as HAIS from Hartley-Anglo-Iranian-Siemens.

The HAIS pipe was a good start but it was soon apparent that the amount of lead required to produce enough pipe was going to be prohibitively expensive and would involve stripping the lead off every church roof for a start. As a result, it was decided that an alternative would be needed that made use of cheaper and more readily available materials such as mild-steel.

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 (Picture) to lay the pipe.

(Henry Hammick explained one day to his son that the Conundrum was short for Cone-ended drum - which described the shape of the drum perfectly. He also explained how he had realized that if you can wrap cotton around a reel you can do the same with mild-steel pipe around a large diameter drum and still be able to unwrap it.)

The first prototypes were tested in May 1942 (across the River Medway), and in June in deep water across the Firth of Clyde, before going into production. With the basic steel pipe for HAMEL supplied by Stewarts & Lloyds of Corby, manufacturing of the final system was carried out by Siemens Brothers at Woolwich, Henley's at North Woolwich, Callender's at Erith and Standard Telephones and Cables at Greenwich. Because of capacity limitations in the UK, some HAIS pipeline was also 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 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/in²) in the pipeline at all times, even during manufacture. Also, 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-feet 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 14 August 1942, using steel from the now near defunct Corby steel works, and six weeks later, on 30 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. This decision necessitated further alterations and additions to the pipeline handling gear. Two further ships were equipped with handling gear, these being HMS Sancroft and HMS Latimer,(later renamed as Empire Baffin and Empire Ridley respectively) 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 use 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.

(According to HA Hammick's son, the towing trials for the Conundrums were carried out using diesel tugs to begin with as these were the most modern and therefore believed to be the most powerful. However, when it was pointed out that the nature of a steam engine was to provide maximum torque at low speed, steam tugs were then tested. These tests involved pulling against a spring balance anchored to a bollard on the quayside; the diesel tugs performed well but the steam tugs pulled the bollard out of the quay.)