TD Williamson (TDW) has introduced of the Clamp Installation Tool (CIT), a new remote-controlled system that makes it possible to install any proprietary clamps or fittings on subsea pipelines in need of repair or to prepare for tie-ins to new pipelines.
The lightweight CIT is operated via remote control through a laptop by an experienced technician onboard a platform or a diving support vessel (DSV). As a result, operational safety is enhanced, and control over clamp installation operations is greatly improved.
The introduction of the new CIT comes on the heels of the remote-controlled Subsea 1200RC Tapping Machine, which was launched by TDW in 2012 to offer a diverless solution to subsea hot tapping in depths of up to 3,000 metres (9,842 feet). Because the most critical part of the hot tapping process is the point at which the drill penetrates a live pipeline, TDW was keen to remove divers from the process and provide a remote-controlled diverless solution. The development of the CIT and the Subsea 1200RC Tapping Machine is the culmination of a concerted effort by TDW to provide a safer, more efficient method.
Subsea hot tapping is necessary to facilitate tie-ins, pipeline repair, and flow assurance. Nearly all subsea hot tap operations – as many as 98 per cent – involve the use of a post-installed mechanical tee with elastomeric pressure sealing elements, while only 2 per cent use hyperbaric-welded tees or pre-installed tees, due to the expense. To offer pipeline operators a cost-effective way to remotely install mechanical tees prior to the hot tap or as part of an integrated hot tap assembly, TDW developed the CIT.
The CIT is small, lightweight and easy to deploy. As with the Subsea 1200RC Tapping Machine, it is a topside-driven tool with a passive remotely-operated vehicle (ROV) interface. The installation package consists of four basic units: a control skid, ROV, clamp or fitting, and the installation tool.
First, the TDW proprietary control skid is attached to the belly of a standard, work-class ROV. The assembly - which consists of the clamp and a proprietary TDW installation frame - is assembled on the deck of the DSV. The entire system is pre-tested to verify that each function performs properly before being lowered (with the clamp halves in closed position) into the sea by the crane on the DSV. The control skid is transported by the ROV travelling alongside the assembly.
Upon arrival at the pipeline, the ROV connects a hot stab to the frame, and the installation tool opens the clamp using cylinder actuation. Technicians onboard the DSV then carry out the bolt engagement program from the laptop. Every function is achieved with a dedicated stab that the ROV picks up from the skid and stabs into the interface panel.
After the body bolts are spun and tensioned to secure the clamp, the longitudinal bolts are secured to energise the seals and activate the structural grips. Technicians visually inspect and monitor the installation via sensors displayed on the laptop, in addition to using cameras affixed to the installation tool and ROV. Pressurisation of the annulus between the seals is conducted via the test-stab to verify the seals.
After the test is accepted, the frame is disengaged from the fitting and recovered to the surface by the DSV. Because the CIT is modular, it can then be used immediately to install additional clamps on the pipeline.
Mike Benjamin, Senior Vice President – Marketing & Technology for TDW, said: “By doing so, we offer a solution that dramatically reduces risks to personnel and increases efficiency. Looking ahead, we are confident that it will soon become the industry standard for all subsea clamping and hot tapping operations, whether they are carried out to pave the way for repair work, tie-ins or chemical injection.”
For more information, visit www.tdwilliamson.com