?1. Main Causes of Leakage

Process gas pipelines require extremely high sealing properties. Leakage (more accurately, "slip") is typically caused by one or more of the following:

1. Pitting and crevice corrosion: This is the most common form of corrosion in stainless steel pipes. Process gases may contain chloride ions (Cl-) and fluoride ions (F-), or chloride ions may accumulate under the insulation due to moisture. These can cause localized corrosion of the stainless steel, eventually penetrating the pipe wall.

2. Galvanic corrosion: When stainless steel pipes come into direct contact with another metal (such as carbon steel flanges, valves, or hangers), the presence of electrolytes (such as moist air or water films) can form a galvanic cell, accelerating corrosion of the stainless steel.

3. Stress corrosion cracking (SCC): The combined effects of tensile stress and certain corrosive media (such as chloride ions and sulfides) can cause brittle cracks in pipes, leading to leaks. Elbows, due to cold working and fluid diversion, experience high residual and operating stresses, making them a high-risk area for SCC. 4. Erosion-Corrosion: If the process gas contains solid particles or droplets, it will impact the outer wall of the elbow at high speed when flowing through it, destroying the passive film on its surface, accelerating metal loss, and ultimately causing wear.
5. Vibration Fatigue: Vibration in the piping system (such as from compressors, pumps, and high-speed airflow) can cause fatigue cracks at stress concentration points such as the elbow, which can gradually propagate and cause leaks.
6. Welding Defects: If the elbow is welded to the pipe, the initial weld may contain defects such as incomplete penetration, porosity, and cracks. These defects may propagate over time and cause leaks.
7. Installation Stress: Improper pipe alignment during installation and forced welding can create excessive internal stress in the elbow, accelerating corrosion and cracking.

?2. Repair Methods

The choice of repair method depends on the severity of the leak, system pressure, the nature of the process gas (whether it is flammable, explosive, or toxic), and whether production can be suspended.

Important Prerequisite:

Safety First! Process gas leaks can pose significant risks, including asphyxiation, poisoning, and explosion. Before any repair operation, the process must be isolated (shutdown, depressurize, purge, and replace) and verified, and safety procedures, including those for hot work, must be followed.

Temporary vs. Permanent: It's necessary to assess whether the repair is intended as a temporary emergency measure or a permanent fix.

Common Repair Methods:

1. Pressure-Proof Plugging (In-Situ Repair) - The most common and effective emergency method.

Clamp Injection Method: A wrap-around clamp is constructed based on the size and angle of the elbow. The clamp is positioned at the leak site, and a specialized sealant is injected into the cavity through the injection holes on the clamp. The sealant fills all gaps under pressure and cures, forming a new seal. This method is suitable for a wide range of pressures and pipe diameters.

Steel Banding: For small holes and low-pressure leaks, stainless steel bands impregnated with sealant can be used for banding and sealing, but the effectiveness and pressure-bearing capacity are not as good as the clamp method.

2. Replace the elbow.

This is the most thorough method. The system needs to be shut down, the damaged elbow removed, and a new stainless steel elbow of the same specifications welded together. Ensure weld quality and conduct nondestructive testing (such as X-ray or ultrasonic testing) and pressure testing.
3. Weld Repair
Small leaks can be repaired by welding, provided the system is completely isolated, purged, and the combustible gas analysis is satisfactory. However, it should be noted that if the leak is caused by corrosion or cracks, repair welding may cause it to expand due to thermal stress, thus treating the symptoms rather than the root cause. Stop holes should be drilled at the ends of the cracks.

?3. Benefits of Using Leak Repair Clamps

The "leak repair clamps" you mentioned generally refer to wrap-around plugging clamps or leak repair clamps, which are the core components of the aforementioned clamp injection method. The benefits of using them are significant:

1. No need to shut down production, resulting in significant economic benefits: The biggest advantage. Repairs can be performed while the system remains operational and under pressure, avoiding the significant production losses caused by shutdowns. This is crucial for chemical and energy companies with continuous production. 2. Fast Installation and High Efficiency: From measuring dimensions to fixture fabrication to on-site installation, the process is mature and takes far less time than traditional production stoppage and replacement methods, significantly shortening troubleshooting time.
3. Safe and Reliable: Professional leak-proofing fixtures are made of high-strength metal (such as stainless steel) and are designed for high pressures. The injected sealant is specifically formulated for various operating conditions (high temperature, high pressure, and media resistance) and forms a long-lasting, stable seal after curing.
4. Wide Adaptability:
Elbow leak repair clamps can be customized in various specifications and angles (90°, 45°, etc.).
They are suitable for leaks in various locations, such as straight pipes, tees, and flanges.
They can address a variety of leak types, including holes, cracks, and pinholes.
5. Excellent Sealing Performance: Through multi-point injection, the sealant evenly fills the fixture cavity, perfectly conforming to irregular leaking surfaces and achieving excellent sealing results.
6. Relatively Low Space Requirements: These fixtures are relatively easy to install in locations with limited space or where welding is difficult.

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, stainless steel pipe repair clamps, high-pressure-resistant pipe repair clamps, and large-diameter pipe repair clamps.

Summary and Recommendations

Cause Identification: After discovering a leak, the first step should be to determine the cause (corrosion? Cracks?). This will help select the most appropriate repair solution and prevent recurrence.
Preferred Option: For critical systems like process gas pipelines, using a customized wrap-around leak repair clamp (clamp injection method) for hot-plugging is currently the most popular, economical, and safest online emergency repair method.
Permanent Solution: After the leak repair clamp is repaired, it should be considered a long-term temporary solution (possibly for several years). During the next scheduled maintenance period, personnel should be assigned to completely replace the damaged elbow to eliminate the potential risk.
Professional Operation: Hot-plugging is a specialized technique that must be performed by a qualified professional team to ensure safety and effectiveness.

Emergency Response Process:

Discover a leak → Report and establish a cordoned-off area → Assess the leak and risk → Contact a professional pressure-sealing company → Measure dimensions and design a fixture → Fabricate the fixture → Install and inject sealant on-site → Repair completed → Include in scheduled maintenance and replacement list.