T.D. Williamson Global Solutions- October 2007

The July issue of Global Solutions carried a story regarding an Australian sub sea hot tapping project in final preparation. Customized TDW SubSea 1000 XL tapping machines were engineered and constructed in Tulsa, tested on simulation vessels in Tulsa and in pressurized under water conditions at the Naval Surface Warfare Division at Carder Rock, Maryland. Special environmentally friendly machine fluids were introduced to assure that, if a fluid release were to happen, no harm would come to the sensitive ecology surrounding the project site.

With testing complete, two identical SubSea 1000 XL tapping machines were sent to a large assembly hanger near Perth, Australia for mating to the valve that would eventually be attached to a 40-inch, 1,900 psi gas line at a depth of 425 feet. Time was spent at the assembly facility training divers who would be attaching and operating the tapping machines. As preparations were nearing completion, a delay was encountered. Because of back-to-back cyclones that struck the area earlier in the year, additional time was required until offshore conditions were acceptable. As a result, all equipment was crated and stored and technicians sent back to America to await a final go-ahead to perform the sub sea tap.

Truck delivers pre-assembled valve and tapping machine to dockside

TDW technicians were called back to Australia and left the U.S. on August 24^th to prepare equipment for transport to the city of Karratha on the northwestern coast, facing the Indian Ocean. Equipment was reassembled and an extra test tap was performed to assure that the machines were ready for the task and to allow divers additional rehearsal time before they worked with the tapping machines in the dark, artificially lighted depths with the added challenges of shifting currents and curious sharks.

Equipment was loaded onboard the Rockwater II dive support ship which set to sea from the Mermaid Dock in Dampier, Australia on Sunday, September 9^th. After an 8 hour boat ride, the ship reached the project site. On September 16^th, a team of three divers descended to coordinate placement of the deployment frame that was lowered with the valve and tapping machine pre-assembled and ready for attachment to the future tap flange already in place on the pipeline. The same team of divers started the hot tapping process at 12:50 p.m. and established penetration by the pilot drill before their shift was over and they were replaced by three more divers. The second dive team successfully completed the tapping process at 10:22 that same night. Helmet mounted cameras allowed TDW technicians on the ship to watch every move and communicate directly with each diver during the entire operation.

Upon completion, the cutter was retracted and the valve closed. The tapping machine with the coupon still inside was raised with the frame assembly and loaded back on board the ship. Equipment was then offloaded from the ship at the dock, crated and sent back to Perth, Australia.

A considerable amount of testing and rehearsal time was invested in this project at the request of the client. It was vital that the sub sea hot tapping process was completed successfully with no extended term stoppages for any reason. Everything used to conduct the tapping process had 100 percent redundant backup, which included technicians and equipment. Every extra day spent on site due to equipment failure or complications would represent a significant cost to the customer. TDW completed the sub sea hot tap in just over six hours with a single cutter. No problems were encountered and the TDW SubSea 1000 XL Tapping Machine performed flawlessly in extreme conditions.

Dive support ship loading equipment

Once back on land, TDW technicians were informed by Australian sources that they had just performed the largest verified sub sea hot tap on record. A great deal of credit for the success of the Australian sub sea hot tap goes to TDW engineers who produced a customized hot tapping machine that was both dependable and highly efficient, and to the TDW technicians who directed the operation from topside by way of the outstanding dive teams who operated TDW equipment like seasoned pros.

Diver cam of second diver next to the SubSea 1000 XL in operation

Information about sub sea hot tapping equipment and processes is available by calling TDW Services at 918-447-5000 or by visiting www.tdwilliamson.com.