I. Project Overview and Construction Objectives
In pipeline maintenance, inspection, or rerouting projects, underwater bladder plugging and hole boring must simultaneously achieve the following objectives:
1. Pipeline Isolation Plugging: By sealing the target pipeline segment with air bags, achieving a waterless or low-pressure environment.
2. Precise Drilling: Holes are drilled at designated locations for easy pipeline connection or equipment installation later.
II. Construction Process and Technical Points
Underwater Air Bag Plugging
Step 1: Preparations and Inspection
● Pipeline Survey: Confirm pipeline material, diameter, wall thickness, flow velocity, and corrosion status using ROVs (underwater robots) or divers.
● Airbag Selection: Choose an appropriate size of airbag based on the pipe diameter (such as rubber airbag, with working pressure matching the pipe internal pressure), and test the airbag's airtightness and inflation performance.
● Equipment Preparation: Equipped with an air compressor, pressure gauge, air supply tube, and emergency repair tools.
Step 2: Airbag Installation and Sealing
● Airbag Transportation: Insert the airbag into the predetermined position within the pipeline using ropes or a traction device, avoiding any twists or scratches to the airbag.
● Positioning and Fixation: Utilize guidance devices to ensure the airbag is positioned at an appropriate upstream/downstream distance from the hole, preventing displacement during the hole-making process.
● Inflatable plug: Inflate slowly to the designed pressure (usually 1.2-1.5 times the working pressure of the pipeline), monitor the sealing condition via a pressure gauge, and check for any leaks at both ends of the pipeline.
2. Underwater Drilling and Holes Cutting
Step 1: Hole Position Confirmation
● Precision Locating: Mark the center point of the hole using a laser distance meter or underwater positioning system, with an error control within ±5mm.
● Environmental Assessment: Remove surface attachments from pipes (such as marine organisms, corrosion), ensuring stable contact of the hole-making tools.
Step 2: Hole Drilling Process Selection
● Mechanical Drilling: Suitable for medium and small diameter pipes, using diamond drill bits or hard alloy cutting tools, paired with a hydraulic power head for layered drilling.
● Waterjet Cutting: Ideal for large diameter pipes or complex materials, offering high cutting accuracy with minimal damage to the pipe structure.
● Blasting Holes (Use with Caution): Intended for specific situations only, requires precise calculation of blast quantity and ensures surrounding safety.
Step 3: Drilling Operation and Protection
● Spray Prevention Measures: Install spray prevention devices (such as valves or baffles) on the pipe surface prior to drilling to prevent the ejection of high-pressure fluids.
● Hole Wall Treatment: Remove burrs and debris to ensure smooth edges around the hole, avoiding damage to subsequent connection equipment.
● Synchronous Sealing Adjustment: Dynamically adjust the airbag position during the drilling process to ensure the sealing effect is not compromised by the hole creation.
Section 3: Key Technical Points
Pressure Balance Control
If the pressure inside the pipeline is high, it is necessary to reduce the pressure or divert the flow first to avoid the balloon from being blown open or a dangerous situation occurring during the opening of holes.
After drilling, fluid discharge is controlled through temporary valves or quick sealing devices.
2. Underwater Operation Safety
Divers are required to wear full-seal diving suits equipped with an emergency oxygen supply system.
○ Utilize ROV-assisted monitoring for real-time transmission of video and pressure data.
Material Durability
○ The airbags are made of reinforced rubber (such as chloroprene rubber + aramid fiber), which is resistant to high pressure and corrosion.
Hole cutting tools are made with wear-resistant coating materials to extend their service life.
Section 4: Safety and Environmental Protection Measures
1. Safety Standards
Warning buoys are set up in the construction area, prohibiting entry of unauthorized vessels.
Regularly inspect the airbag pressure and the status of the piercing equipment to prevent sudden leaks.
Develop emergency response plans (e.g., for airbag rupture, equipment failure), and equip with spare airbags and repair materials.
2. Environmental Requirements
Prevent leakage of medium (oil, wastewater, etc.) inside the pipeline during sealing and hole-making processes; set up oil booms or absorbent materials if necessary.
Waste recycling and processing (such as cutting scraps, old airbags) to prevent water pollution.
V. Quality Control and Inspection
Seal off acceptance
The airbag's sealing integrity is verified through pressure testing, with no bubbles or pressure drop observed.
Divers conduct underwater visual inspections of the sealing effect.
2. Hole Inspection Approval
○ Utilize endoscopes or ultrasonic technology to inspect the hole size and the quality of the hole walls.
Record the hole positions, diameters, and construction parameters to ensure compliance with design requirements.
Section 6: Common Questions and Solutions
Defective airbag sealing: Immediately stop drilling, replenish inflation or replace the airbag, and check if there are sharp objects piercing the airbag through the pipe surface.
2. Hole Offset: Adjust the guide device for repositioning, and use a boring tool for correction if necessary.
3. High-pressure Water Jet Impingement: First reduce pressure or divert the flow, then gradually bore holes to prevent divers from being swept away by the water current.
Section 7: Summary
Underwater pipeline air bag plugging and hole drilling require precise positioning, efficient plugging, and professional drilling techniques. Strict safety monitoring and environmental protection measures ensure the project is completed efficiently and safely. It is recommended to be carried out by a qualified professional team, with detailed construction plans and emergency response procedures.
