🧿Part 1: Repair Methods for 6.0MPa High-Pressure Pipelines

Repairing high-pressure pipelines is more than simply inserting a clamp or replacing a seal; a rigorous process must be followed. The core principles are: safety first, a plan first, and qualified personnel.

Required Steps Before Repair:

1.System Isolation and Pressure Relief:

Complete Isolation: Close upstream and downstream isolation valves and ensure they are securely sealed. For critical systems, installing blind plates for physical isolation is the safest method.

Complete Pressure Relief: Open the pressure relief valve or vent valve to safely discharge the medium (water, gas, oil, etc.) in the pipeline to a designated location. A pressure gauge must be used to confirm that the pipeline pressure has dropped to zero.

Media Evacuation and Replacement: For flammable, explosive, toxic, or corrosive media, purging, cleaning, and replacement (e.g., with nitrogen) are required, and testing (e.g., for explosives, oxygen, and toxicity) is required.

2.Site Preparation and Safety Measures:

Demarcate the work area: Set up cordoned areas and safety signs. Firefighting Preparations: Have appropriate fire extinguishers and fire sand available.
Personal Protection: Maintenance personnel must wear appropriate personal protective equipment, such as hard hats, safety glasses, anti-corrosion gloves, and safety shoes. Respirators are also required when working with special media.
Work Permit Application: Strictly follow approval procedures for special operations such as hot work, work at height, and work in confined spaces.

Common Repair Techniques:

Different repair methods are selected based on the defect type and location:

1.Pipe Section Replacement Method:
Applicable Situations: Extensive corrosion, thinning, cracks, severe deformation, or irreparable defects in the pipeline.
Operation Method: Cut the damaged pipe section and replace it with a pre-prepared new section of the same material, specification, and pressure. Welding is usually used for connection.
Requirements: The work must be performed by a certified welder in accordance with the welding procedure specifications. Nondestructive testing and pressure testing must be performed upon completion.
2.Welding Repair Method:
Applicable Situations: Localized, shallow surface cracks or pinholes.
Operation Method: Grind away the defect and then weld the repair.
Requirements: Extreme caution is required! A thorough assessment of the defect is required to determine whether it is suitable for repair welding. This procedure must be performed by a highly qualified welder and undergo 100% non-destructive testing.

3.Clamp Injection Method (Under Pressure Sealing):

Application: Emergency repairs when shutdown is unavailable. This is a temporary measure, and a planned shutdown must be scheduled for permanent repairs.

How it works: A specially designed clamp is used to wrap around the leak. A special sealant is then injected into the seal cavity through the clamp's grease injection valve under high pressure, forming a new sealant layer to stop the leak.

Requirements: This procedure requires specialized personnel and a professional company. The risk is extremely high and requires careful calculation and design.

4.High-Pressure Pipe Repair with a Clamp:

Application: Repairs can be performed under pressure using a 6.0 MPa high-pressure pipe repair clamp without shutting off the water supply.

How it works: The high-pressure pipe repair clamp is wrapped around the leaking pipe.

Post-Repair Verification:

Non-Destructive Testing: All welds and repairs must undergo non-destructive testing, such as radiographic or ultrasonic testing, to ensure the absence of internal defects. Pressure Testing: After repairs are completed, the pipeline system or repaired section must be pressure-tested (usually using water). The test pressure should be 1.25-1.5 times the design pressure, and the pressure should be maintained for a sufficient period of time to verify its strength and leak-tightness.

Part II: Prevention Strategies for High-Pressure Pipeline Leaks

Prevention is far better than repair. Establishing a systematic preventive maintenance system is key to ensuring the safe operation of high-pressure pipelines.

1.Design, Installation, and Material Control:
Qualified Materials: Ensure that all quality certification documents for pipes, valves, flanges, fasteners, and gaskets are complete, and that the materials and pressure ratings meet design requirements.
Professional Installation: Installation is performed by a qualified team, ensuring the quality of welding and fastening.
2.Regular Inspection and Monitoring:
Statutory Inspection: In accordance with national regulations, special equipment inspection agencies conduct regular and comprehensive inspections.
Enterprise Self-Inspection:
Macroscopic Inspection: Regular inspections are conducted to check the pipelines for abnormal vibration, deformation, insulation loss, and surface corrosion. Thickness Inspection: Use an ultrasonic thickness gauge to regularly measure the thickness of elbows, tees, reducers, and other areas susceptible to corrosion and erosion to monitor wall thinning.
Nondestructive Testing: Regularly perform nondestructive spot checks on critical welds and areas of stress concentration.
Leak Detection: Use equipment such as flammable/toxic gas alarms or infrared thermal imagers (which can detect cryogenic liquid leaks) for online monitoring.
3.Corrosion Control:
External Corrosion Protection: Maintain the integrity of the anti-corrosion and insulation layers.
Internal Corrosion Protection: Add corrosion inhibitors or use lining materials based on the media characteristics.
Cathodic Protection: For buried pipelines, use sacrificial anodes or impressed current cathodic protection.
4.Operation and Maintenance Standards:
Smooth Operation: Avoid drastic fluctuations in pressure and temperature to prevent phenomena such as water hammer and surge.
Prevent Overpressure: Ensure safety valves and pressure relief valves are within their calibration validity period and function properly. Integrity Management: Establish a pipeline technical file, manage all inspection, repair, and change records, apply risk management principles to assess pipeline conditions, and develop a predictive maintenance plan.

Summary and Emphasis

6.0 MPa is high pressure and extremely dangerous! All repair work must be performed after thorough isolation and pressure relief.
Welding repairs must be performed by certified welders, and non-destructive testing and pressure testing must be conducted.
The key to prevention lies in regular inspections, monitoring wall thickness, and establishing a comprehensive maintenance management system.

Finally, and most importantly: If you are not a qualified professional and have a qualified team, do not attempt to repair high-pressure pipelines yourself! Contact a professional pressure pipeline installation and repair company immediately.