One, underwater steel pipe pile cutting technology
Cutting Method Selection
Select cutting technology based on steel pipe pile material, diameter, thickness, and water depth conditions.
Submerged Oxygen-Arc Cutting: Suitable for low-carbon steel and low-alloy steel, with high efficiency; however, pay attention to heat-affected zone control.
Metal - Arc Cutting: Suitable for conductive metal materials, with deep cutting capability, but arc burns should be prevented.
Underwater Plasma Cutting: Suitable for high precision requirements, capable of cutting metals and non-metals, but with higher equipment costs.
○ Mechanical Cutting (such as hydraulic saws, grinding wheels): Suitable for thin-walled steel pipes or cold cutting applications to avoid thermal deformation.
2. Cutting Construction Process
○ Initial Preparation:
Underwater Inspection: Utilize ROVs or divers to confirm the position, corrosion status, and surrounding environment of steel pile.
Develop cutting plan: Determine the cutting sequence (e.g., cutting from the edge to the center), support and fixation measures, and residual stub treatment.
Cutting Operation:
Arcing and Cutting Initiation: Divers utilize professional cutting tools (such as underwater cutting torches) to arc from the designated position, gradually expanding the incision.
■ Wreck Removal: After cutting, use lifting equipment or underwater robots to hoist the remnants to the designated location.
○ Cautionary Notes:
Avoid sparks contacting flammable gases or structures during cutting, and ensure divers maintain a safe distance from cutting equipment.
Consider the effect of hydrostatic pressure on equipment for deep-sea operations and choose pressure-resistant cutting tools.
3. Key Technical Points
Cutting Precision Control: Utilize laser positioning or guiding devices to ensure verticality of the cut, avoiding tilt that could lead to difficulties in subsequent sealing.
Thermal Impact Protection: Insulate adjacent structures (such as concrete foundations) to prevent thermal damage.
○ Stub removal: Cut steel pipe piles must be cleaned promptly to avoid affecting navigation or subsequent construction.
Section 2: Diving Plug Technology
1. Method of Sealing Selection
Select technology based on the application of steel pipe piles (such as drainage pipes, structural piles) and sealing requirements (temporary/permanent).
Blow-Molded Plug: Suitable for temporary sealing, with flexible operation; however, ensure the balloon's pressure resistance matches the pipeline pressure.
○ Steel plate welding plug: Suitable for permanent sealing, requires diver underwater welding or prefabricated plug installation.
Composite material sealing: such as epoxy resin infusion or polyurethane foam sealing, suitable for complex shapes or tiny cracks.
2. Diving Plug Installation Process
Preparation Phase:
Confirm the internal medium of steel pipe piles (water flow, gas, corrosive substances) and pressure.
Divers wear protective gear, equipped with emergency oxygen and communication devices.
○ Plugging operation:
■ Positioning and securing: Divers place the sealing device (such as an airbag) precisely at the designated location and stabilize it with a towline or securing device.
■ Implementation of Blocking Measures:
● Airbag Sealing: Slowly inflate to the designed pressure and monitor the sealing effect through a pressure gauge.
● Welding Plug: Divers underwater weld the sealing plate, ensuring no leaks in the weld.
Post-processing:
After sealing, conduct underwater inspections (such as diver visual checks, sonar detection) to confirm tightness.
Clear the work area to ensure no tools or materials are left behind.
3. Cautionary Notes
○ Pressure Control: In case of high-pressure water flow within the pipeline, it is necessary to reduce pressure or divert the flow first to prevent the airbag from being washed away or to avoid explosion caused by high temperature during welding.
○ Material Selection: The sealing material must be corrosion-resistant and withstand high pressure, such as stainless steel sealing plates or high-strength rubber air bags.
Emergency Measures: On-site backup sealing equipment (such as airbag repair tools, spare welding equipment) is provided to address sudden leaks.
Section 3: Safety and Quality Control
Safety Measures
Divers hold professional qualifications, adhere to decompression protocols, and prevent decompression sickness.
○ Establish cautionary lines in construction areas and equip with lifeboats and emergency medical equipment.
Regularly inspect the performance of diving equipment (such as oxygen bottles, communication devices) and cutting tools.
2. Quality Control
○ Planarity measurement of cut surfaces: Evaluate cutting quality with an underwater camera or ultrasonic thickness gauge.
○ Sealing Integrity Test: Verify the sealing effect through pressure testing or dye penetration test.
○ Document Record: Full documentation of construction parameters (such as cutting time, sealing pressure) to ensure traceability.
IV. Application Scenarios and Cases
Application Scenarios
Port Renovation: Remove abandoned steel pipe piles and seal remaining holes.
Bridge Construction: Underwater pile foundation cutting and sealing to ensure structural stability.
Environmental Engineering: Seal abandoned pipelines to prevent pollution leakage.
2. Reference Cases
In a certain cross-sea bridge project, underwater plasma cutting technology was employed to dismantle old steel pipe piles, and permanent sealing was achieved through steel plate welding, ensuring the safety of new pier foundation construction.
○ The wastewater pipeline in a chemical industrial park was temporarily sealed using high-strength rubber bladders, complemented by divers' underwater repairs, successfully preventing the leakage of hazardous substances.
V. Summary
Submerged steel pipe pile cutting and diving sealing should be combined with engineering requirements to select appropriate technology, strictly adhere to safety regulations, and ensure operation efficiency and long-lasting sealing through precise construction and quality control. It is recommended to be carried out by a qualified professional team and a detailed emergency response plan should be formulated.
