🧿1. Treatment Methods for Leaks at DN500 Stainless Steel Pipe Flange Connections

For large-diameter stainless steel pipes such as DN500 (nominal diameter 500 mm), leaks at flange connections can generally be addressed according to the following process:

Step 1: Safety Preparation and Site Assessment

1. System Isolation and Pressure Relief: Immediately close the valves upstream and downstream of the leaking pipe section to isolate the piping system. Open the drain valve or pressure relief valve to completely release the pressure in the pipe.

2. Site Survey: Carefully inspect the leak point.

Determine the cause of the leak: Is it due to aging or damage of the gasket? Loose flange bolts? Or is there damage to the flange sealing surface (such as corrosion, scratches, or deformation)?

Assess the severity of the leak: Is it dripping, line flow, or spraying? This determines whether under-pressure repair is possible and the appropriate repair method.

3. Prepare Tools and Materials: Based on the assessment results, prepare new gaskets, bolts, tools (such as wrenches, hydraulic torque wrenches, etc.), and safety equipment.

Step 2: Select a specific treatment method based on the cause of the leak.

Method 1: Tighten the bolts (suitable for minor leaks where the bolts are only loose)

Operation: Tighten all bolts on the flange gradually, using a symmetrical, staggered pattern. Apply even force to avoid overtightening on one side, which can cause the flange to deflect and exacerbate the leak.

Limitations: If the gasket is damaged or the flange surface is uneven, this method will only temporarily alleviate the problem and will not permanently resolve it.

Method 2: Replace the gasket (the most common and thorough method)

1. Shutdown and Drain: Ensure the pipeline is completely isolated, depressurized, and the media inside has been drained.

2. Bolt Removal: Remove half of the bolts, leaving the other half loose to support the flange.

3. Pry the Flange Seam: Use a pry bar to gently pry open the gap between the flanges and remove the old gasket.

4. Clean the Sealing Surface: Thoroughly clean the sealing surfaces of both flanges to ensure there is no residual gasket, rust, or oil. Check that the sealing surfaces are smooth and flat. 5. Install the new gasket: Select a new gasket of the correct material and specifications (such as a stainless steel spiral wound gasket or graphite composite gasket), apply a small amount of lubricant or anti-seize agent, and accurately center it in the flange.
6. Close the flange and tighten the bolts: Remove the pry bar, close the flange, and compress the new gasket. First, tighten all bolts by hand. Then, use a torque wrench to tighten them in a symmetrical, staggered sequence, in multiple increments (e.g., 50%, 80%, 100%) to the specified torque. This is crucial for ensuring a good seal.

Method 3: Use a sealant (as a temporary emergency measure)

For systems that cannot be shut down immediately, specialized pipe sealants (such as injection sealants for pressure-resistant leaks) are available. However, these are typically temporary solutions, and permanent repairs must be performed when an opportunity arises.

Method 4: Repair the flange sealing surface (if the flange surface is damaged)

If the flange sealing surface has deep scratches or localized corrosion, repairs are necessary before replacing the gasket. The pit can be filled with a metal patch (such as epoxy), or professional on-site machining (in-process milling) can be performed to restore smoothness.

🧿 2. Advantages of Using Leak Repair Clamps

When traditional shutdown and gasket replacement are impractical (e.g., when shutdown is unavailable, the cost of shutdown is prohibitive, or flange damage is severe), pipe leak repair clamps are a highly effective and reliable solution. This advantage is particularly evident for large pipes, such as DN500.

A leak repair clamp (also commonly known as a "leak repair clamp" or "clamp-type leak repair clamp") is a device that wraps around the leak to create a seal.

The key advantages are as follows:

1. Fast and efficient, significantly reducing downtime
This is the biggest advantage. Traditional gasket replacement requires a series of time-consuming steps, including depressurization, evacuation, removal, cleaning, installation, and re-pressure testing. Installing a leak repair clamp typically takes only tens of minutes to an hour, enabling rapid resumption of production and minimizing the financial losses caused by downtime.

2. Operates under pressure, enabling repairs without interrupting production.
Specialized pressurized leak repair clamps allow installation while the pipeline is under pressure and the medium is flowing. This is crucial for continuously operating industries such as the chemical, power, and water supply industries, avoiding system downtime.
3. Easy to operate and low labor intensity.
Compared to removing heavy, large-diameter flange bolts (DN500 bolts are very thick and require large hydraulic tools), installing a leak repair clamp typically requires only closing the two halves of the housing and tightening a few bolts, saving time and effort, and requiring relatively low operator skill.
4. Strong adaptability and reliable sealing.
The sealing ring inside the leak repair clamp is typically made of high-performance rubber (such as NBR, EPDM) or polyurethane. It has excellent elasticity and can effectively compensate for misalignment, gaps, or minor sealing surface damage between flanges.
It not only repairs flange leaks, but also repairs cracks, holes, and other defects in the pipeline itself, providing a multi-purpose solution.
5. High safety.
It avoids the high risks associated with directly removing flanges under pressure. The installation process of the leak repair clamp is relatively safe and controllable. 6. Significant Cost-Effectiveness
Although a DN500 leak repair clamp is expensive in itself, the associated overall costs (downtime, labor costs, and emergency response costs) are often much lower. It's a one-time investment, with a long-term inventory to respond to unexpected leaks.

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

Conventional Treatment: For planned repairs or situations where downtime is acceptable, shutting down the system and replacing the gasket is the most standardized, cost-effective, and long-term solution.
Emergency and Efficient Treatment: For unexpected leaks, situations where downtime is unavoidable, or where downtime would be costly, using a leak repair clamp is the preferred solution. It embodies the core principles of "speed, safety, and efficiency" in modern industrial maintenance.

Therefore, for your DN500 stainless steel flange leak, if conditions permit and a permanent repair is desired, choose method two (gasket replacement). If time is of the essence and downtime is a concern, investing in a high-quality leak repair clamp specifically designed for DN500 stainless steel flanges is a wise move. We recommend keeping a stock of these leak repair clamps in your spare parts library just in case you need them.