When a pipeline suffers a deformation or develops a leak in the offshore environment, operators must respond decisively within an instant’s notice. Most often, they must perform leak repair and install structural clamps to temporarily contain the leak, while maintaining flow. This action affords the operator time to implement a more permanent repair solution. This timely and efficient response is only plausible if the operator stocks leak repair clamps as part of an existing emergency pipeline repair system (EPRS) and if clamps can be installed immediately.
Assuming an EPRS is already part of a company’s proactive emergency response plan, T.D. Williamson (TDW) is offering a way for operators to more efficiently install repair clamps via the recently developed Clamp Installation Tool (CIT). The new remote-controlled CIT makes it possible to quickly install proprietary clamps or fittings on subsea pipelines in need of repair, as well as to prepare them for tie-ins to new pipelines. The lightweight CIT is operated from a laptop by an experienced technician on-board a platform or dive support vessel (DSV). As a result, operational safety-enhanced and control-over-clamp installation operations are greatly improved.
Costs reduced by remote control
When responding to an emergency, the combination of the CIT and clamps is essential. It’s critical for deepwater pipelines, where access for intervention purposes can only be achieved by remote control and where it can dramatically speed up the intervention process. It also reduces vessel use, saving additional time and money.
With EPRS becoming the standard among well-positioned organisations, CIT could serve as an instrumental addition to most programs. Readily deployable using any standard work-class remotely-operated vehicle (ROV), the CIT is easily retrieved by its modular design, meaning that it is ready for immediate re-use where multiple interventions are required. It can also be used to install any mechanical clamp or hot tap tee, making it a flexible tool for a wide range of EPRS products.
In addition, the CIT is welcome news for EPRS clubs that stock a variety of clamps in different sizes. The system offers a quick intervention capability down to 3,000 m. The introduction of the new CIT goes hand-in-hand with the remote-controlled Subsea 1200RC Tapping Machine, which was introduced by TDW in 2012. Between these two innovations, divers have effectively been removed from the equation, once
again increasing safety and reducing risk for operators.
As subsea hot tapping plays a central role with tie-ins, repair works, and flow assurance, nearly 98 per cent of subsea hot tapping operations use a post-installed mechanical tee with elastomeric pressure sealing elements. TDW developed the CIT to provide pipeline operators a less expensive way to remotely-install mechanical tees before any hot tap operation.
The “˜how-to’ of remote installation
As with the Subsea 1200RC Tapping Machine, the CIT is a topside-driven tool with a passive ROV interface. The CIT is a modular system comprising clamp-running tools framed around the clamp, and a control system consisting of skid-mounted hardware and a laptop. A standard work-class ROV provides power to the CIT and communication to the DSV via an umbilical.
First, the control skid is attached underneath the ROV, and the clamp and frame assembly is assembled on the deck of the DSV and hooked to the vessel’s crane. The entire system is pre-tested for proper function before being lowered into the sea. The control skid is transported by the ROV travelling alongside the clamp assembly. When it arrives at the pipeline, the ROV connects a hot stab to the frame, and the CIT opens the clamp using cylinder actuation. Technicians on-board the DSV engage the bolts from the laptop. Every function is carried out with a dedicated stab that the ROV picks up from the skid.
After the body bolts are spun and tensioned to secure the clamp, the longitudinal bolts are secured to activate structural grips and energise the seals. Technicians inspect and monitor the installation via sensors and cameras installed on the CIT and ROV, respectively. To verify the seals, pressurisation of the annulus between the seals is conducted by a test-stab. The removable frame is then disengaged from the fitting and transported to the surface. With its modular design, the CIT may be used again immediately.
The development of the CIT in conjunction with the Subsea 1200RC Tapping Machine is the culmination of a concerted effort by TDW to provide a safer, more efficient method of subsea pipeline repair and intervention.
For more information visit www.tdwilliamson.com