🧿Part 1: When are high-pressure pipelines used?

High-pressure pipelines generally refer to piping systems designed for pressures above 10 MPa (100 kgf/cm²). They are used in many industrial sectors with stringent pressure and strength requirements, primarily including:

1. Petrochemical and Refining Industries
Hydrogenation Processes: Hydrocracking and hydrorefining processes require extremely high pressures (up to 20 MPa) and temperatures to break heavy oils into lighter oils or remove impurities such as sulfur and nitrogen.
High-Pressure Separation: Post-reaction materials require gas-liquid separation in high-pressure separators, and the connected pipelines are also subject to high pressure.
Synthesis Processes: These processes, such as methanol synthesis and ammonia synthesis, use high pressure to promote chemical reactions and improve efficiency.
2. Energy and Power Industries
Power Plant Boilers: In steam power plants, the superheated steam generated by the boilers is extremely high pressure (subcritical and supercritical units can reach pressures above 17-25 MPa). The main steam pipe and reheat steam pipe are typical high-pressure pipes. Nuclear power plants: The primary main pipeline carries coolant (high-pressure water), with pressures reaching over 15 MPa to prevent the water from boiling at high temperatures.
3. Oil and gas field production and transportation
Water/gas injection: High-pressure water or gas is injected into oil reservoirs to maintain formation pressure and increase oil recovery. The injection pipeline pressure is very high.
High-pressure gathering and transportation: The wellhead pressure and gathering and transportation network pressures of some high-yield gas fields are very high.
4. Military and aerospace industries
Rocket fuel transportation: Rocket engine fuel and oxidizer delivery systems require extremely high-pressure pipelines.
Submarines and ships: High-pressure air systems, hydraulic systems, etc.
5. Industrial gas industry
Gas compression and storage: The compression, liquefaction, and filling processes of gases such as hydrogen, nitrogen, and oxygen require high-pressure pipelines.
Materials science and research
Ultra-high-pressure experimental equipment: Used in materials synthesis and physics experiments, pipelines and containers capable of withstanding pressures of tens or even hundreds of thousands of atmospheres are required.

Characteristics of high-pressure pipelines: They are typically constructed of high-strength alloy steel (such as chromium-molybdenum steel) or special stainless steel, have very thick pipe walls, and require extremely stringent welding and inspection requirements.

🧿 Part Two: How to Repair a High-Pressure Pipeline Leak?

High-pressure pipeline leaks are extremely dangerous emergencies, potentially causing serious accidents such as injection injuries, explosions, fires, and poisoning. The core principle of handling them is: safety first; operating under pressure is strictly prohibited.

Repairs must be performed by a professionally trained and qualified team according to strict procedures. The following is the standard process:

Step 1: Emergency Response and Shutdown and Pressure Relief (The Most Critical Step)

1. Immediate Reporting and Evacuation: The first person to discover the leak should immediately report it to the control room and activate the emergency alarm. Evacuate non-essential personnel from the leak area and establish a cordoned-off area.
2. Emergency Shutdown/Shutdown: The control room operator immediately initiates the emergency shutdown procedure, shutting down upstream equipment (such as compressors, pumps, boilers, etc.).
3. Safe Pressure Relief: The leaking pipeline and its associated systems are safely and controllably depressurized using established process flows. Typically, the medium is directed to a flare system for combustion or discharged to a safe location through a vent valve. Ensure that the system pressure has dropped to atmospheric pressure (0 MPa) and that isolation is complete.
4. Isolation and Purging: Close the isolation valves upstream and downstream of the leak to achieve double isolation. If necessary, purge with an inert gas (such as nitrogen) to displace toxic and flammable media in the pipeline. Tests should confirm that the concentrations of flammable and toxic gases are within acceptable limits and that the oxygen content is within safe limits.
5. Energy Isolation (Tagout and Lockout): Tagout and lockout all relevant valves and switches to ensure no erroneous operation during maintenance.

Step 2: Select and Implement Repair Methods

Repairs can only begin after completing the above safety preparations. Depending on the type and size of the leak defect and the condition of the pipeline, select the following methods:

1. Replace the pipe section (the most common and thorough method)

Applicable scenarios: Severe pipeline corrosion, large-scale thinning, major cracks, or defects. Steps: Cut all defective pipe sections, replace them with prefabricated new sections of the same material and specifications, and then weld them.
Requirements: The welding process must be qualified and the welder must be certified (high-pressure certified). 100% non-destructive testing (such as RT radiography or UT ultrasonic testing) must be performed after welding.
2. Welding Repair
Applicable: Small cracks, pinholes, or localized corrosion pits.
Steps: Grind to remove defects, prepare the groove, and then perform the repair weld.
Requirements: This requires extremely high welding skills and must be performed by highly qualified welders. Preheating is required before welding (for alloy steels), and post-weld heat treatment is required for stress relief. Non-destructive testing must also be performed to confirm the absence of new defects.
3. Clamping (Under Pressure Sealing, performed by a specialized team in special circumstances)
Applicable: Special circumstances where shutdown or isolation is not possible. This is an unconventional emergency measure with extremely high risk and must be performed by a specialized "Under Pressure Sealing" team. Method: Use a special metal clamp to wrap around the leak. Then, inject a special sealant into the clamp cavity. The sealant cures under the action of the leaking medium to form a leak-proof layer.
Note: This method does not address corrosion and strength issues with the pipeline itself. It is only a temporary measure and requires a planned downtime for permanent repairs.
4. Use sealants/straps (temporary emergency measure, only for extremely low-pressure or non-critical pipelines).
This method is generally not recommended for high-pressure pipelines due to its poor reliability and should only be used as a temporary auxiliary control measure during the pressure relief process.

Step 3: Post-Repair Testing and Restoration

1. Inspection and Testing: After the repair is completed, the following must be performed:
Non-destructive Testing: Perform RT or UT testing on all welds to ensure quality.
Pressure Testing: Perform a hydrostatic test (test pressure approximately 1.5 times the design pressure) to verify the strength and sealing of the repaired area. The use of gas for pressure testing is strictly prohibited!
2. Restoration: After passing the pressure test, remove the blind plate, restore isolation, slowly introduce medium pressure, and conduct a comprehensive inspection to confirm there are no leaks before gradually resuming normal production.

The housing is typically made of metals such as ductile iron and carbon steel, which are corrosion-resistant and high-strength. It can last the same life as the original pipe, eliminating the need for frequent repairs. Baoshuo brand carbon steel half joints are available in a variety of rubber materials, including NBR, EPDM, FKM, and silicone rubber. The half joint body is available in Q235 carbon steel and 304 and 316L stainless steel.

The following are Baoshuo brand oil-resistant pipe repair clamps, high-temperature-resistant pipe repair clamps, acid- and alkali-resistant pipe repair clamps, 304,316,2205，stainless steel pipe repair clamps, high-pressure-resistant pipe repair clamps, and large-diameter pipe repair clamps.

Summary and Emphasis

High-pressure pipeline leaks are emergencies. The top priority is to ensure personal safety: immediately shut down the pipeline, relieve pressure, and isolate the pipeline.

Permanent repairs are strictly prohibited!

All repairs must be performed by qualified personnel according to established procedures.

Permanent repairs usually involve replacing the pipe section or welding repairs, accompanied by rigorous non-destructive testing and pressure testing.

Putting leaks under pressure is a specialized, high-risk technique and is strictly prohibited for non-professionals.