Kỹ thuật khoan nóng và ngắt dòng cho đường ống dẫn khí áp suất cao của CNOOC trong dự án xây dựng tuyến đường sắt Fuzhou-Xiamen

Project Snapshot

Element	Details
Client	China Railway 16th Bureau Group Co., Ltd.
Location	Fuzhou City, Fujian Province, China
Core Challenge	Relocating a live, high-pressure (2.0 MPa) natural gas pipeline for a new high-speed rail line without interruption, involving multiple high-risk simultaneous operations.
JSW Solution	Custom-designed four-point line stop and bypass system, augmented with pneumatic plugging bags for double isolation, executing a full sequence of hot taps, stops, cold cutting, and reinstatement.
Key Results	1. Safety: Zero incidents, leaks, or environmental impact. 2. Economic: Avoided massive shutdown-related losses for the client. 3. Efficiency: Successfully delivered within the project’s critical path schedule.

The Challenge: Rerouting a Critical, High-Pressure Gas Artery for High-Speed Rail Without Shutdown

When the construction of a new Fuzhou-Xiamen railway section intersected with a live CNOOC high-pressure natural gas pipeline, China Railway 16th Bureau faced a critical infrastructure dilemma:

• Zero Shutdown Mandate: The φ406×8mm pipeline, operating at 2.0 MPa, was a vital energy artery. A traditional shutdown for modification would cause unacceptable supply disruption and massive financial loss.
• Extreme Safety Risks: Performing welding and cutting on a pipeline carrying flammable gas under high pressure presented a potentially catastrophic hazard. The margin for error was nonexistent.
• Complex Technical Scope: The project required 16 separate hot taps (DN400, DN350, DN200, DN50), 4 line stops, and the installation and commissioning of 150 meters of bypass piping. Precision and flawless sequencing were paramount.
• Tight Schedule: The railway’s overall timeline demanded the pipeline relocation be completed safely and efficiently within a strict 35-day window from June 15 to July 20, 2021.

The client needed more than a construction crew; they needed a service provider with proven expertise, extensive project experience, and superior risk management capabilities as a specialized pipeline contractor.

The JSW Solution: A Customized High-Pressure Hot Tapping, Bypass, and Plugging Procedure

As an established manufacturer of pipeline equipment and a dedicated engineering services contractor, JSW designed and executed an integrated “Live Intervention, Full Control, Multi-Barrier Safety” strategy.

Our solution centered on applying advanced hot tapping and line stopping technology to install a temporary bypass, isolating the section for modification without interrupting flow. Key technical customizations included:

1. Full-Encirclement Split Tee Welding: Using specialized procedures for the L360M steel and 3PE coating, we welded full-encirclement reinforcing saddles at four critical locations. These provided the robust branch connection foundation essential for safe high-pressure natural gas pipeline isolation.
2. Four-Point Bypass Isolation System: Unlike simpler single-point stops, we engineered a system with four DN400 line stops and two DN350 bypass lines. This redundant design ensured continuous flow and operational safety even in the unlikely event of a single component issue, demonstrating a sophisticated pipeline bypass installation and plugging method.
3. Double-Isolation with Pneumatic Plugs: At the critical cut-out points, we deployed DN200 pneumatic plugging bags as a secondary barrier. After setting the mechanical stops, we inserted and inflated high-pressure bags downstream, creating a “mechanical + pneumatic” dual-isolation zone. This significantly enhanced safety during the non-welding (cold) cutting phase.
4. Comprehensive Nitrogen Purging & Monitoring: All tapping and plugging equipment was rigorously pressure-tested and purged with nitrogen before use, eliminating oxygen and any ignition risk within the equipment chambers.

Implementation: Precision Execution and Meticulous Management

At the project site in Fuzhou, Fujian Province, JSW’s certified team translated the plan into precise action:

1. Pre-Engineering & Simulation: We conducted detailed stress analysis using the pipeline’s design parameters (4.0 MPa) to simulate conditions during the operation, ensuring structural integrity.
2. Controlled Worksite Setup: We established standardized excavation pits with safe access/egress routes and full safety signage, creating a controlled environment for high-risk tasks.
3. Sequenced Critical Path Operations:
   • Phase 1: Completion of all full-encirclement fitting welds and non-destructive testing.
   • Phase 2: Sequential execution of hot taps for the stops, bypass, balance, and bag ports, followed by bypass line installation.
   • Phase 3: Commissioning of the bypass lines to divert gas flow.
   • Phase 4: Critical DN400 line stopping operation to isolate the mainline section.
   • Phase 5: Deployment of pneumatic bags, execution of cold cutting, and removal of the existing pipe section.
   • Phase 6: Installation of the new spool, removal of stops and bags, decommissioning of the bypass, and final plugging of all fittings.
4. 24/7 Monitoring & Readiness: Continuous monitoring of pressure and gas concentration was maintained throughout, with emergency response equipment and personnel on standby.

Results & Value Delivered: Safety, Schedule, and Significant ROI

The project was not only successful but delivered exceptional, quantifiable value:

• Flawless Safety Record: Achieved zero safety incidents, zero product releases, and zero environmental impact during the entire high-pressure pipeline isolation procedure.
• Zero Operational Impact: Our onshore pipeline hot tapping service prevented millions of dollars in potential economic losses for CNOOC and downstream users, ensuring uninterrupted regional energy supply.
• On-Schedule Delivery: The project was completed within the allotted 35-day window, directly supporting the overall timeline of the Fuzhou-Xiamen railway construction.
• Technical Benchmark Established: This project serves as a premier hot tapping and line stopping project case study, successfully validating a complex, multi-point intervention on L360M steel gas pipeline, setting a gold standard for future infrastructure relocation projects.

“The professionalism and unwavering commitment to safety demonstrated by the JSW team were outstanding,” said the project manager from China Railway 16th Bureau. “They were more than just a contractor; they were a true technical partner. Their meticulous planning and calm execution gave us, as the main contractor, complete confidence during this high-risk operation.”

About JSW: Your Pipeline Integrity Partner

JSW is both an advanced manufacturer of pipeline maintenance equipment and a full-spectrum engineering services company. We specialize in:

• Pipeline Relocation & New Installation
• Hot Tapping & Line Stopping Services
• Pipeline Emergency Response & Integrity Maintenance
• Pipeline Integrity Management Consulting

From R&D to field execution, JSW provides end-to-end services, ensuring your energy infrastructure operates safely, efficiently, and without interruption.

Looking for a reliable pipeline solutions partner for your next critical infrastructure project? Contact the JSW expert team today for a customized proposal.