🧿1. What is the maximum liquid temperature that cast iron pipes can withstand?

The temperature resistance of cast iron pipes depends on their material (regular gray cast iron or ductile iron) and whether they are lined with refractory materials.

1. Ordinary gray cast iron pipes:
In the absence of internal thermal stress concentration, the short-term upper temperature resistance limit is approximately 350°C.
If subjected to long-term operation at temperatures exceeding 200-250°C, their mechanical properties will significantly degrade (they will undergo "growth," an irreversible volume expansion), becoming brittle and eventually rupturing. Therefore, long-term use above 200°C is not recommended.
2. Ductile iron pipes:
Their temperature resistance is generally superior to that of ordinary gray cast iron, and their short-term temperature resistance is similar to that of gray cast iron.
However, for long-term use, the recommended upper temperature limit is around 200°C. Some high-performance ductile iron pipes may allow slightly higher temperatures, but the manufacturer's specifications must be strictly followed.

Important Note:

Sudden temperature changes are the biggest enemy of cast iron pipes. Even if the temperature is within a safe range, thermal stresses caused by sudden heating or cooling can easily cause cast iron pipes to crack.

If the medium being transported is continuously at high temperatures (such as in steam pipes), steel or special alloy steel pipes are generally chosen over cast iron pipes.

🧿2. How to repair high-temperature pipe leaks?

When dealing with high-temperature pipe leaks, safety is paramount! High-temperature media (hot water, steam, chemicals) can cause severe burns. The repair method depends on the leak size, pressure, and whether the operation can be shut down.

Step 1: Safety Preparation and Assessment

Identify the medium: Determine whether the leak is water, steam, or another hazardous chemical.

Assess the risk: Measure or estimate the temperature and pressure near the leak point. Never touch the pipe directly with your bare hands.

Take precautions: Wear personal protective equipment such as scald-proof clothing, a face mask, and thick, insulated gloves.

Establish a cordoned-off area: Keep unauthorized personnel away.

Step 2: Select a repair method based on the situation.

Method A: Emergency/Temporary Repair (Suitable for situations where immediate shutdown is not possible)

1. Clamp Plugging (Leak Repair Clamp):
For small holes or cracks, a high-temperature plugging clamp can be used. These clamps typically consist of two halves with a sealing strip, which are bolted to the leak site to create a seal.

This is the most common and relatively reliable temporary method.

2. Sealing Adhesive:
Use a high-temperature resistant metal patching compound or sealing rod (such as an inorganic adhesive based on epoxy or silicate).
To apply the adhesive, clean the surface of the leak and press the adhesive firmly against the leak with your hands or a tool to allow it to cure. This method is suitable for low-pressure, small leaks.

3. Strapping:
High-temperature, high-pressure strapping tape, such as high-temperature, high-pressure strapping tape, is wrapped around the leak like a bandage and forms a rigid sleeve after curing. It is suitable for repairing longitudinal cracks.

Method B: Permanent Repair (Requires shutdown, cooling, and pressure relief)

1. Replace the pipe section:
This is the most thorough and reliable method. Cut the damaged pipe section and replace it with a new section of the same specifications. Connect the pipe using flanges or welding (if it's steel pipe).
2. Welding Repair:
Extreme caution is advised with cast iron pipes! Ordinary cast iron has poor weldability and requires experienced welders using specific cast iron welding rods (such as nickel-based rods) and specialized techniques (such as preheating and slow cooling). Otherwise, the weld is prone to cracking, causing further damage. It is generally not recommended for emergency repairs.

🧿Third, the benefits of using high-temperature leak repair clamps

High-temperature leak repair clamps (also known as patch clamps or leak repair clamps) are highly effective tools designed specifically for pipeline repairs. They combine the advantages of the aforementioned temporary methods with more reliable performance.

Their main benefits are as follows:

1. Excellent High-Temperature Resistance:
Specially designed, their sealing elements (such as rubber gaskets and graphite gaskets) and body materials (usually stainless steel or ductile iron) are designed to withstand high temperatures. Common products can withstand temperatures exceeding 300°C or even higher, perfectly matching the temperature limit of cast iron pipes. 2. Fast and Efficient, Minimizing Downtime:
The two-part structure allows for extremely quick installation (typically a few minutes to half an hour) without the need for special tools, significantly reducing production interruptions and making it crucial for continuously operating plants.
3. No Downtime Required, Leak-Proofing:
This is one of its greatest advantages. Installation can be performed without completely shutting down the pipeline, maintaining a certain level of pressure and fluid flow, greatly facilitating emergency repairs.
4. Reliable Sealing and Strong Pressure Capacity:
The bolts provide uniform circumferential tightening force, combined with high-performance gaskets, effectively sealing leaks and withstanding high pipeline operating pressures.
5. Wide Adaptability:
It can be used to repair various types of damage, such as pinholes, cracks, fractures, and corrosion holes.
It is suitable for a variety of pipe materials, including cast iron, steel, and PVC pipes.
6. High Safety Factor:
It eliminates the risks of hot work (such as welding), ensuring a safer installation process.

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. 

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

The recommended long-term safe operating temperature for cast iron pipes should not exceed 200°C.

When a high-temperature leak occurs, a safety assessment should be performed first. Then, depending on the situation, temporary repairs such as leak plugging clamps and high-temperature leak repair clamps should be selected.
High-temperature leak repair clamps are an ideal choice for repairing high-temperature pipeline leaks because they are fast, safe, reliable, and heat-resistant, minimizing downtime and safety risks. For permanent repairs, pipe section replacement should be arranged during a planned outage.