The 1.2-kilometer-long buried pipeline of the 33,000 Nm³/h air separation unit in Phase II of Guangxi Hengyi has been fully completed

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At 15:00 on December 7, 2025, as the last excavator left the 33,000 Nm³/h air separation unit area of Guangxi Hengyi Phase II, the 1.2-kilometer-long buried pipeline was fully completed, and the backfill compression test passed successfully on the first attempt. Applause erupted at the scene — the 206 Project Team in Zhejiang managed to complete this task, which the client described as \"the most complex and challenging one of all\", in just 37 days and nights, thereby creating a valuable window of time for subsequent work such as pipeline installation, instrumentation cable laying, and equipment commissioning. “The \"underground lifeline\" allows no margin for errors of even a millimeter. This pipeline carries four different systems: circulating cooling water, cryogenic liquids, instrument air, and fire-fighting water. It passes through 7 high-risk areas such as utility tunnels, equipment foundations, and cable tunnels; the maximum elevation difference along its length is 6 meters. At times of peak concurrent operations, up to 6 different organizations work on this pipeline at the same time. The BIM team of the project department completed the 3D collision analysis 3 weeks in advance, resolving 42 conflicts on the drawings ； The measurement team used a total station combined with GPS for dual verification, keeping the slope error of the trench within ±2 mm and achieving \"one-time setting and one-time completion\". Rainy weather, water seepage, soft soil – problems don’t last overnight. In mid-November, continuous rain fell in Guangxi, and water seepage occurred at the K3+150 section. The project team immediately implemented a dual approach of \"wellpoint dewatering + steel sheet piles,\" resulting in a 40-cm drop in water level within 12 hours and zero displacement of the slope ； Rain shelters were installed simultaneously to ensure that the welding humidity remained below 85%; the first-time inspection pass rate was 98.9%, which is 6 percentage points higher than the industry average. For weld joint corrosion protection, a three-stage inspection system of \"primer + heat-shrink sleeve + spark testing\" is employed, ensuring 100% compliance. 24-hour shifts – operations continue without interruption. During peak periods, 4 specialized teams, 20 skilled technicians, and 11 large-scale machines work round the clock to carry out the tasks ； The mobile app reports progress in real time; there is a video “daily review meeting” at 8 p.m., ensuring that issues are resolved on the same day. The joint office of the owner, supervisor, and designer is stationed on-site, with responses to drawing changes provided within 2 hours, achieving an 80% speed increase over traditional processes.