TDW Offshore Services L.L.C. (TDW), a leading supplier of pipeline services and equipment, announced that it successfully completed a pipeline pressure isolation operation in the Gulf of Mexico for a major operator.

    The operation made it possible for the operator to safely replace a faulty shut down valve (SDV) located above the riser on a platform situated off the coast of Louisiana.

    The riser leads to a pipeline that plays a central role in transporting gas through a key transportation system. When it became apparent that an SDV on this line would have to be replaced, the operator examined the situation closely. The engineers concluded that they were not confident that the two downstream valves would be capable of isolating the pressure while the faulty valve was replaced.

“Double-block and monitor” isolation offers maximum safety, control.

    To ensure that the SDV would be safely replaced, TDW was retained to provide a field-proven solution. TDW would perform a “double-block“ isolation against the gas pressure in the designated riser using two SmartPlug® isolation plug modules linked together. TDW would monitor the location of the SmartPlug modules continuously as they traveled along the pigging route using its remotely-operated SmartTrack™ tracking and pressure-monitoring system, providing further assurance that pressure in the riser would remain properly isolated during installation of the new SDV.

     “By using this method, the operator would not only create a safe working environment for the valve replacement operation, its in situ gas inventory would be maintained at working pressure,” said Mike Benjamin, Vice President of Offshore Pipeline Solutions for TDW. “The operation would be achieved without venting or flooding the line, which would disrupt flow and cause downtime on neighboring
developments.”

    Rigorous safety checks and tests prepare the way

    In keeping with new U.S. safety, environmental and risk mitigation regulations, TDW and the operator prepared for the operation by carrying out extensive hazard identification exercises and equipment testing. Extraordinary levels of on-site operational redundancy were incorporated in preparation for the operation.

    Working from the platform, TDW launched the SmartPlug modules, using the SmartTrack system to monitor pressure and track them. The modules were pigged in for 80 feet – traveling under a flow rate of 30 – 40 gallons per minute at approximately 131 bar (1900 psi) – until reaching their destination near the top of the riser.

    TDW set the downstream SmartPlug module and bled the topside pressure to approximately half of the riser pressure. With data communicated by the SmartTrack system confirming the integrity of the downstream seal, TDW technicians set the upstream SmartPlug module and monitored the pressure between modules until they were confident that the module was holding pressure. The SDV could be safely replaced.

    Isolation pressure monitored continuously for 12 days

    The SmartPlug modules remained in the riser for 12 days while the operator replaced the SDV. Throughout this period, TDW took hourly pressure readings of the isolated section using SmartTrack “through pipe wall” communications technology, which relies on extremely low frequency (ELF) electromagnetic waves to transmit isolation integrity data to a transceiver, which in turn relays it to a control center. TDW assessed the data around-the-clock until the SDV was installed. Utilizing the double-block isolation created by the SmartPlug modules, the crew performed a leak test on the repaired section. After confirming the integrity of the newly installed valve, pipeline pressure was equalized and the SmartPlug modules un-set and retrieved, allowing normal production to resume.

    TDW’s aim is to ensure that every customer’s asset operates at the highest levels of safety and sensitivity to the environment. “We are very pleased with the isolation operation that was carried out,” said Steve Appleton, Regional General Manager – Gulf Coast and Caribbean for TDW. “The TDW team was extremely professional, and the SmartPlug modules performed impeccably. Working in cooperation with this valued customer, we achieved a safe, uncompromising isolation that allowed for the replacement of the SDV in a timely manner. That it was achieved without venting the line or flaring product is significant.”

About TDW Offshore Services

    TDW Offshore Services provides customers with the products and services they need to construct and maintain pipelines. The company’s world-class engineering capability has resulted in numerous innovative products and services. TDW Offshore Services has an engineering staff that excels in customized design and fabrication of a wide range of repair clamps installable by remotely operated vehicle (ROV). The SmartPlug tool from TDW Offshore Services is the world’s leading pipeline pressure isolation technology.

    TDW Offshore Services is a subsidiary of T.D. Williamson, Inc., the world leader in pipeline equipment and services. The company delivers safe integrity solutions for onshore and offshore applications. Experts provide hot tapping and STOPPLE® plugging, pipeline cleaning, integrity inspection, pigging and non-tethered plugging, and pig technology services for any pressurized pipeline system in the world.