June 2019, Vol. 246, No. 6

Tech Notes

Hot-Tapping, Plugging Enable Shutdown-Free Pipe Replacement

Pipeline solutions provider T.D. Williamson (TDW) paired its SmartPlug isolation system with hot-tapping and plugging (HT&P) services to enable a pipeline replacement at a Saudi Arabian industrial plant while the facility remained in service.

The 20-inch pipeline, which transports fuel oil 11.5 miles (18.5 km) to a water desalination and power generation facility, required pipe spool replacements at two underground road crossings.

To avoid interrupting the plant’s operation during the replacement project, TDW performed seamless back-to-back, double-block in-line isolations at each road crossing, using two remote controlled, non-intrusive SmartPlug tools.

Realtime 24/7 monitoring verified the integrity of each isolation, which remained in place for five days. The replacement works were completed one week ahead of schedule.

Comprehensive Solution

TDW provided a comprehensive isolation solution at both road crossings. The twin operations included preparation of the pipeline for the mid-line repair operation through safe hot-tapping, isolating the pipeline with SmartPlug tools and installing completion plugs.

The company manufactured and supplied 2-inch fittings and performed hot-taps on the pipeline at each of the road crossings. This was to allow draining and purging of the pipe section between the two SmartPlug tools in the line.

TDW loaded, launched and pumped the tools through the pipeline using crude oil, and positioned, tracked and operated the tools using the in-line tool tracking system. The tools were unset and retrieved through the operator’s existing scraper traps.

The efficiency of on-site tool maintenance meant the tools were cleaned, inspected, decommissioned and recommissioned within 24 hours, allowing the same tools to be used for both isolations. 

Because the pipeline remained in operation, it allowed the transfer of oil to the plant during pumping of SmartPlug tools to and from the work sites. Since the pipeline remained oil-filled during the replacement work, recommissioning wasn’t required. Only the sections that were replaced were drained and decommissioned.

Pipe Geometry

The operation wasn’t without its challenges, however. According to Morgan Swanlund, project manager or this operation. While the tools are capability of passing 3-D bends – their limits were tested this time.

“The main technical challenge was for the SmartPlug tools to traverse a total of 373 bends of radius 1,800 mm, typically positioned back-to-back, in each of the two runs,” Swanlund said. “This was achieved in great part due to the pre-engineering design of the tool by the engineering team in Stavanger, Norway.”

He added TDW put in place special precautions to safeguard people and physical assets during the operation, which took place from May through August – the peak of the Saudi Arabian summer. P&GJ

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