July 23, 2012

New underwater tapping unit

The new 1200RC compact remote-controlled subsea hot tapping machine is lightweight and allows hot tapping to be carried out from the safety of a diving support vessel (DSV) or platform.

The critical part of the hot tapping process is the point at which the drill penetrates the pipe, which has now been rendered diverless by the 1200RC. The direct control and visibility from a laptop will help improve hot tapping, giving way to a more efficient and safer process, the company says.

While the installation of the hot tap assembly and subsequent removal of the machine will still require diver assistance when a preinstalled tee is not present, the performance of the tap itself is remotely controlled by a company technician on board the DSV or platform. The system is a topside-driven hot tap machine with passive remotely operated vehicle (ROV) interface, which means that it is a stationary ROV with its hydraulics and control system attached to the 1200RC, and operated from an on-board laptop.

The new subsea system has demonstrated the feasibility of conducting the tapping operation entirely by remote control. But the system offers more than just reduction in diver activity. The new technology offers total control and visibility of the tapping operation where there was none before. Built-in sensors allow continuous recording of pressures, temperatures, rotation, and movement of the pilot drill and cutter. Sensors shed light on what is going on inside the enclosed space right at the heart of the cutting operation. The laptop-based program facilitates control remotely, rather than relying on the divers' manual handling of the cutting process. The end result is a level of accuracy and quality that is not possible in diver-based operations, the developer points out.

The 1200RC was tested and successfully deployed in 2011 on a tapping operation for a project in water depths of 298 ft. The tap size was 16 in. on an existing 28 in. gas pipeline. The job was conducted from a DSV in a cutting operation that lasted about 2 hr. Flow through the pipeline was uninterrupted.

Source: T.D. Williamson Inc., 5727 S. Lewis Ave., Suite 300, Tulsa, OK 74105-7144.

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