TPi January 2017

business & market news

and expanded within the pipe to both grip the inner diameter and also form a seal. The Test End normally has a valve attachment that enables water or air to be passed into the pipe and pressurised up to 16 bar. This made them suitable for the purpose required for the HDD installation. The problem was how to get them into the Multi Puller and have them work effectively as pulling heads while still enabling them to be used to pass ballast water into the pipes. The modifications to the Multi Puller and the Test Ends involved, within the nose section of the Multi Puller, connecting all the Test Ends to the towing plate such that they were rigidly held in place. The individual pipes were placed over the grippers of the Test Ends, which were then expanded to hold the pipes in place. As added security, to ensure that in gripping the pipes they did not expand or deform at the towing end, each pipe was fitted with a stainless steel collar to offer a platform against which the Test End could seal and grip. The Test Ends were then connected together so that the contractor, when putting water into just one of the 125mm diameter pipes, could fill all the pipes to the same level at the same time. Using this design not only enabled the contractor to fill the pipes with ballast as and when required, but also meant that

Multi Puller and Test Ends

assembled and leak tested and the pull- in operation commenced. The operation was successfully com- pleted without incident. Pipe Equipment Specialists Ltd – UK enquiries@pipe-equipment.co.uk

the full length of the pipe string did not have to be welded together and laid out before the final pull-in operation could take place. Once thepull-inoperationwas underway, new lengths of the pipe string could be welded into place as required, with the final lengths being added just prior to the time when the ballast pumping was needed. Having connected together the pipes at the towing head, using just one of the smaller diameter pipes meant that all the pipes could be ballasted at the same time. With this plan in place, once the main boring and reaming work was completed, the pipe bundle was

www.pipe-equipment.co.uk Stockton Drilling Ltd – UK info@stocktondrilling.com www.stocktondrilling.com

Detail of the final reamer/towing head/pipe bundle assembly

LEADING STOCKHOLDER IN NICKEL ALLOYS

Seamless Pipe and Fittings

Alloy 200/201 Alloy 400 Alloy 600 Alloy 625 Alloy 825 Alloy C276* * seamless & welded

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