Relocating a Critical DN400 Gas Pipeline for the Fuquan Highway Expansion Without Shutdown

Commissioning hot tapping & plugging equipment on DN400 high-pressure natural gas pipeline during relocation (Fuzhou, 2023)

Project Spotlight: 

Подробности
ClientFujian Natural Gas Co., Ltd. (A subsidiary of CNOOC)
LocationCangshan District, Fuzhou City, Fujian Province, China
DateApril 18 – May 18, 2023
Core ChallengeRelocate 1,450 meters of live DN400 natural gas pipeline operating at 4.0 MPa that was obstructed by highway expansion construction, with zero interruption to downstream gas supply and strict adherence to 30-day timeline.
JSW SolutionSegmented live double block and bleed (DBB) hot tapping and plugging technology with temporary bypass installation, executed in two phases across multiple work zones, utilizing JSW proprietary high-pressure equipment and certified welding procedures.
Key ResultComplete pipeline relocation of 1,821.7 meters completed on schedule with 100% gas supply continuity, zero safety incidents, and all welds passing pressure integrity tests, enabling uninterrupted highway construction progress.

The Challenge: A High-Stakes Conflict Between Infrastructure and Energy Supply

In the bustling district of Cangshan, Fuzhou, a major infrastructure upgrade—the widening of the Fuquan Expressway connecting line—posed a direct threat to a vital energy artery. A DN400 natural gas pipeline (Φ406×7.9mm, L415 steel), operating at 4.0 MPa, lay directly in the path of planned interchange ramps and a rotary. Approximately 1,450 meters of this high-pressure pipeline was either encroached upon or situated perilously beneath the footprint of new concrete pile foundations.

For the asset owner, Fujian Natural Gas Co., Ltd., the dilemma was severe. A conventional shutdown-and-relocate approach would mean cutting off gas supply to downstream users for an extended period, resulting in significant commercial losses and community disruption. The pipeline relocation was non-negotiable for the highway project, but the cost of interruption was unacceptable. The client needed a pipeline services contractor capable of executing a live pipeline intervention that guaranteed:

  • Zero supply interruption to end-users.
  • Absolute safety for personnel and the public during construction adjacent to and underneath highway infrastructure.
  • Precise execution on a tight, 30-day timeline to align with the highway construction schedule.
  • Technical excellence in working with high-grade L415 steel and maintaining the integrity of the 3PE coating.
Workers performing hot tapping and plugging on L415 DN400 high-pressure natural gas pipeline during the pipeline relocation project for highway expansion (Fuzhou, 2023)
Crane and workers installing hot tapping & plugging equipment on DN400 L415 natural gas pipeline in the pipeline relocation construction site (Fuzhou, 2023)

The JSW Solution: Precision Engineering with Live Double Block and Bleed Technology

As a specialized pipeline services company and equipment manufacturer, JSW proposed a technically advanced and operationally safe solution: a segmented live hot tapping and plugging operation using the Double Block and Bleed (DBB) method. This approach allowed us to install temporary bypasses and isolate sections of the live line for cutting and tie-in, all while gas continued to flow uninterrupted through the mainline.

Our custom-engineered solution addressed every client concern:

  1. Comprehensive Pre-Engineering Survey & Planning: Before any fieldwork, our engineers conducted a detailed survey alongside the client’s team. We mapped every hot tapping and plugging point (4 points across 2 segments), designed the temporary pipeline bypass installation route, and planned all excavation and shoring for the high-pressure work pits, hot tap pits, and tie-in pits in the challenging urban-soil conditions of Anping and Huji villages.
  2. Deployment of Proprietary Hot Tapping & Plugging Equipment: We utilized JSW-manufactured split-tee fittings, high-pressure tapping machines, and plugging heads specifically rated for the pipeline’s 7.5 MPa design pressure. Our equipment’s reliability was non-negotiable for this live pipeline intervention.
  3. Phased, Risk-Mitigated Execution Plan: The project was strategically divided into two phases—Qingliang Village segment followed by Anping/Huji segment—to manage resources and risk effectively, aligning perfectly with the client’s node.
Рабочие устанавливают оборудование для горячей врезки в газопровод DN400 L415 во время работ по переносу (Фучжоу, 2023 г.)
Рабочие монтируют двойное оборудование для забивания пробок на газопроводе высокого давления DN400 (проект переноса газопровода в Фучжоу, 2023 год)

The Execution: A Symphony of Technical Skill and Project Management

The implementation demonstrated JSW’s dual strength as a hands-on contractor and a master project manager.

Phase 1: Qingliang Village Segment (15-Day Sprint)

  • Days 1-7: Upon site handover, our crew immediately executed safe excavation and hydraulic shoring for all critical work pits. Simultaneously, we set up site facilities and prepared the first pipeline section.
  • Day 8: A formal joint construction condition confirmation with the client ensured all safety and technical prerequisites were met—a step that builds trust and prevents errors.
  • Days 9-15: The core hot tapping and plugging sequence began:
    1. Precision Welding: Certified welders performed in-service welding of JSW split-tee fittings onto the live L415 steel pipeline, following stringent procedures to prevent burn-through.
    2. Hot Tapping: Using our tapping machines, we safely drilled into the 4.0 MPa gas stream to create connections for the bypass.
    3. Bypass Installation & Commissioning: A pre-fabricated temporary bypass line was installed and pressurized, becoming the new flow path for the gas.
    4. Plugging & Isolation: Plugging heads were inserted through the tees to create a double block and bleed isolation on the old pipeline section.
    5. Cutting, Tie-in & Restoration: The isolated old pipe section was cut, the new DN400 natural gas pipeline segment was welded in place, and the site was restored. Upon completion, the process was reversed to transfer flow back to the new permanent line.

Phase 2: Anping & Huji Village Segment (15-Day Execution)
Following the same disciplined protocol, our mobilized team replicated the success in the second, more complex area with multiple highway encroachments. The experience gained in Phase 1 allowed for even smoother execution, demonstrating the scalability of our pipeline services.

Подготовка к установке байпаса трубопровода после горячей врезки на газопроводе DN400 (проект переноса расширения магистрали, 2023 г.)
Рабочие выполняют многоточечные горячие врезки и заглушки на газопроводе DN400 L415 во время строительства переезда (Фучжоу, 2023 г.)

Results & Benefits: Quantifiable Success and Strengthened Partnership

The JSW team delivered a textbook example of a complex pipeline relocation for highway expansion. The results speak for themselves:

  • 100% Gas Supply Continuity: Achieved zero interruptions in natural gas delivery to the community and industries throughout the entire pipeline relocation process.
  • Flawless Safety Record: Completed over 1,821 meters of new high-pressure pipeline construction and all live intervention work with zero safety incidents, despite working in confined pits near live traffic.
  • On-Time, On-Budget Delivery: All work was completed within the stringent 30-day window (April 18 – May 18, 2023), ensuring no delays for the critical highway construction project.
  • Technical Excellence Validated: The integrity of all welds and the new pipeline section passed all non-destructive testing (NDT) and pressure tests on the first attempt.

Client Testimonial:
“The highway expansion was on a critical path, and the thought of a pipeline shutdown was untenable. JSW didn’t just offer a service; they provided a guaranteed solution. Their expertise in hot tapping and plugging pipeline technology turned a high-risk problem into a seamless operation. Their team’s professionalism, from engineering to execution, was exceptional. They were a true partner, not just a contractor.”
— Project Manager, Fujian Natural Gas Co., Ltd. (Simulated)

Сварка трубных фитингов для оборудования горячей врезки на газопроводе высокого давления DN400 L415 (место переноса газопровода, 2023 год)
Рабочие герметизируют концы труб после горячей врезки и заглушки на газопроводе DN400 (проект расширения магистрали, 2023 г.)

About JSW Pipeline Services

JSW is a global leader in specialized pipeline services and an innovative manufacturer of pipeline intervention equipment. We bridge the gap between engineering and execution for the world’s most demanding energy and utility assets.

Our Services Include:

  • Live Pipeline Interventions: Hot Tapping, Plugging, Line Stopping, Pipeline Bypass Installation.
  • Pipeline Modifications: Natural Gas Pipeline Relocation, Replacement, and High-Pressure Pipeline Construction.
  • Emergency Response & Maintenance: Leak Repair, Valve Insertion, Pipeline Integrity Management.

Why Choose JSW?
We combine the hands-on reliability of a top-tier field contractor with the technical precision of an equipment OEM. This unique position allows us to design and execute solutions that are not only effective but also optimally efficient and safe. When you face a challenge involving live pipeline intervention or complex pipeline relocation, partner with the experts who build the tools and master the techniques.

Ready to discuss your pipeline challenge? Contact JSW Pipeline Services today for a confidential consultation.

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