An isolation first for safe valve replacement
Published by Elizabeth Corner,
Liquids management is an ongoing challenge for natural gas operators in the Eagle Ford shale play. Pigging to displace pipeline liquids is essential to maintaining throughput, minimising the potential for corrosion, and providing access to valuable condensates.
When leaking valves on both the launcher and receiver jeopardized pigging operations on two, 24 in., 100 km (62 miles) natural gas pipelines located approximately 150 m (492 ft) apart, the operator needed to intervene before the seals failed and it was no longer safe to open or close the trap doors.
Before the valves could be replaced, however, the operator needed to isolate the pipelines and connect them to a bypass system that would allow service to continue to three downstream gas plants.
After evaluating a variety of methods used to isolate pipelines during repairs and maintenance, the operator chose a non-intrusive isolation combined with a hot tap and bypass solution, provided by global pipeline solutions provider T.D. Williamson (TDW).
Rather than resorting to blow-down – which would have been expensive and time-consuming, especially considering the 75 bar (1100 psi) of natural gas inside the pipelines – TDW provided an alternative solution that combined hot tapping and its 24 in. SmartPlug® non-intrusive isolation system for pressurized pipelines. This was the first time the two technologies had been used together onshore in the lower 48 states. It was also the first time that TDW pigged a SmartPlug in and out of an autolauncher; although the autolauncher is designed to pig intelligent tools, it had been primarily used to allow multiple urethane pigs to be loaded at one time and released at predetermined intervals for the liquids management programme.
Because the SmartPlug tool has bi-directional capabilities, it was used to isolate both the launcher and receiver sides. TDW also employed its proprietary SmartTrack™ communication equipment to track and monitor the SmartPlug tool during the pigging and pipeline isolation processes. In addition, TDW installed fittings to enable a permanent bypass between the two pipelines and a connection to a third 16 in. pipeline from the metering station.
“The two valves that were replaced were significantly leaking to the point that additional mitigations (valve sealant, air mover, venting) were required to insert the SmartPlug into the launcher and receiver,” Project Engineer Patrick Moran said.
“The innovative combination of TDW products and services enabled the client to avoid costly alternatives, such as blowing down the system, and to keep downstream customers online, without production delays,” Moran added.
Read the article online at: https://www.worldpipelines.com/equipment-and-safety/19102017/an-isolation-first-for-safe-valve-replacement/
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