Small-diameter pipes are widely used in burners, boilers, and waste incineration equipment. Due to their limited internal space, workers and construction tools may have difficulty entering the pipe. This makes conventional refractory castable installation more challenging.

So, how should refractory materials be installed when the internal diameter of a burner or boiler pipe is small?

The appropriate material and installation method should be determined according to the pipe diameter, operating temperature, gas velocity, wear, and corrosion conditions.

Common solutions include refractory coating, wear-resistant coating, and self-flowing refractory castable.

1. Why is installation difficult in small-diameter pipes?

As the pipe diameter decreases, the available working space becomes increasingly limited.

Traditional refractory castable installation normally requires mixing, placing, molding, and vibration. In a small-diameter pipe, insufficient working space can make vibration difficult and may result in uneven lining thickness, insufficient compaction, or local defects.

This is particularly important for burner pipes, boiler ducts, waste incineration ducts, elbows, and tees.

2. Refractory coating for small-diameter pipes

For pipes with limited internal working space, refractory coating is often a convenient solution.

Unlike conventional castable, refractory coating does not normally require intensive vibration. The material can be applied directly to the internal wall using suitable hand tools.

For pipes exposed to severe abrasion or erosion, a wear-resistant refractory coating can be selected to improve the service life of the lining.

Anchoring components can also be installed on the pipe wall to improve the bonding and mechanical stability of the refractory lining.

3. Self-flowing castable for small-diameter pipes

When refractory castable is required by the design, self-flowing castable can be considered for certain small-diameter straight pipes.

A properly sized internal mold can be prepared and positioned inside the pipe. The self-flowing castable is then placed into the space between the pipe wall and the mold.

Because of its good flowability, self-flowing castable can reduce or eliminate the need for conventional mechanical vibration when properly mixed and installed.

After the material reaches the required demolding strength, the internal mold can be removed.

4. Installation of elbows and tees

For elbows, tees, and other complicated pipe sections, refractory coating can provide greater flexibility during installation.

Anchors or a suitable supporting mesh structure can be installed on the internal wall before applying the refractory material.

The refractory coating is then applied layer by layer and properly compacted and leveled to avoid voids or weak areas.

For areas exposed to severe abrasion, a material with higher wear resistance should be selected according to the actual operating conditions.

5. How to select refractory materials?

The material should be selected according to the actual working conditions.

6. Conclusion

For small-diameter pipes used in burners, boilers, and waste incineration systems, conventional refractory castable can be difficult to install because of limited working space.

In general:

Small-diameter pipe → refractory coating;

Severe abrasion → wear-resistant coating;

Straight pipe requiring cast-in-place lining → self-flowing castable;

Elbows and tees → refractory coating with suitable anchoring/support structure.

The final material and installation method should be determined based on the operating temperature, gas velocity, medium, abrasion level, pipe diameter, and required lining thickness.

For a specific project, providing the pipe internal diameter, operating temperature, medium, gas velocity, and required lining thickness can help determine a more suitable refractory material and installation method.