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(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 using Vertical Triple Ram Pumps manufactured by Tangye Pumps, Cornwell Works in Birmingham. with an operating capability of 1500psi at 3000rpm, 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 l