I. Overview of Rock Wool Insulated Steel Pipe
Rock wool insulated steel pipe is a highly efficient, insulated transmission pipe designed specifically for underground or above-ground heating networks, suitable for transporting hot water, steam, and other high-temperature fluids.
The insulation layer is made of high-density rock wool, which offers excellent thermal insulation and fire resistance. The outer protective pipe effectively resists moisture and corrosion, and withstands external soil pressure, ensuring long-term, safe operation of the pipe in complex environments.
II. What is rock wool insulated steel pipe?
Rock wool prefabricated insulated steel pipe mainly consists of three parts:
i. Working Steel Pipe (Inner Layer)
This pipe is made of carbon steel or stainless steel and is used to transport media and can withstand high temperatures and high pressures.
Common standards include: GB/T 8163, GB/T 9711, ASTM A106, API 5L, etc.
ii. Rockwool insulation layer (middle layer)
High-density rockwool boards or felts are used, offering excellent thermal conductivity (approximately 0.035-0.045 W/m·K), significantly reducing heat loss.
Rockwool is a Class A non-combustible material with fireproofing, heat insulation, and sound absorption properties.
iii. Outer Pipe (Outer Layer)
Depending on the environment, you can choose from the following:
Polyethylene (PE) Pipe: Lightweight, moisture-resistant, and corrosion-resistant, suitable for medium-temperature underground pipe systems;
Galvanized Steel Pipe: Compressive and impact-resistant, suitable for high-temperature or above-ground systems;
Fiberglass Reinforced Plastic (FRP) Pipe: Corrosion-resistant and waterproof, suitable for high-humidity or coastal areas.
III. Rock wool insulated steel pipe production process
| Step | Process | Description |
|---|---|---|
| 1 | Steel Pipe Manufacturing | Select seamless or welded steel pipes, cut to length, and perform internal and external pickling or sandblasting. |
| 2 | Pipe Inspection | Check dimensions, wall thickness, mechanical properties, and surface quality. |
| 3 | End Processing | Precision end machining, threaded or flanged connections for easy on-site installation. |
| 4 | Rock Wool Wrapping | Apply high-density rock wool tightly around the pipe to ensure uniform thickness and compactness. |
| 5 | Moisture Protection (Optional) | Cover with aluminum foil or waterproof film to prevent moisture penetration. |
| 6 | Outer Protective Pipe Assembly | Use galvanized steel, fiberglass, or PE protective pipes to provide mechanical protection. |
| 7 | Joint Sealing | Apply sealing adhesive or special end caps at pipe joints to ensure continuous insulation. |
| 8 | Finished Product Inspection | Conduct pressure testing, leak testing, and insulation performance checks. |
| 9 | Cutting and Packaging | Cut to order length, protect pipe ends, and bundle for packaging. |
| 10 | Factory Delivery | Ship to construction site or customer warehouse after inspection is completed. |
IV. Application fields of rock wool insulated steel pipe
i. Urban Underground Heating Pipeline Network
Features: Pipes are mostly buried, transporting medium-temperature hot water or steam, and are predominantly medium to large diameter.
Selection Guidelines:
Galvanized steel outer sheath is recommended for corrosion, moisture, and mechanical protection.
The insulation layer thickness is generally 50–100 mm, depending on the pipe diameter and medium temperature.
The steel pipe material can be Q235B or 20# carbon steel to meet pressure requirements.
ii. Industrial Hot Water and Steam Pipeline
Features: Withstands medium to high temperatures and pressures, may traverse complex terrain, or be laid outdoors.
Selection Guide:
Outer sheath available in galvanized steel or fiberglass reinforced plastic (FRP);
Recommended steel pipe materials: 16Mn, 20#, or stainless steel (304/316L);
Rockwool insulation layer thickness can be increased to 80–120 mm to reduce heat loss.
iii. Thermal pipelines for power plants and boilers
Features: Transport high-temperature steam or hot water, requiring high pressure resistance and energy efficiency.
Selection Guidelines:
Steel pipe material: High-strength carbon steel or alloy steel;
Outer sheath: Galvanized steel or fiberglass reinforced plastic (FRP);
Insulation layer thickness: 100–150 mm to improve heat loss control.
iv. Chemical, petrochemical, and metallurgical industry pipelines
Features: Pipes may come into contact with corrosive media or operate in humid environments.
Selection Guidelines:
Outer sheath: Glass fiber reinforced plastic (FRP) or epoxy-coated steel;
Steel pipe material: Stainless steel or alloy steel;
The insulation layer must be airtight to prevent the infiltration of moisture and chemicals.
v. Building and residential heating systems
Features: Pipes are mostly small to medium diameter, hot water temperatures are generally ≤95°C, and are buried or laid above ground.
Selection Guidelines:
Outer sheathing can be PE pipe, which is easy to install and low-cost;
Insulation thickness 30–50 mm;
Ordinary carbon steel pipe material can meet pressure requirements.
V. Frequently Asked Questions about Rockwool Insulated Steel Pipes
i. What media and temperatures are suitable for rock wool insulated steel pipes?
A: Rock wool insulated steel pipes are primarily used for transporting high-temperature fluids such as hot water, steam, or hot oil.
Hot water pipes: ≤ 120°C
Steam pipes: ≤ 450°C (depending on pipe material and pressure).
When purchasing, select the appropriate pipe material and rock wool insulation thickness based on the pipe medium temperature to ensure pipe safety and energy efficiency.
ii. How to choose the thickness of the pipe insulation?
A: The thickness of the insulation layer depends on the pipe diameter, medium temperature, and allowable heat loss.
Small diameter hot water pipes: 30–50 mm
Medium and large diameter steam pipes: 80–150 mm
When purchasing, refer to the supplier’s standard thickness table and combine it with project heat loss calculations to determine the most appropriate thickness.
iii. How to choose the outer sheath material?
A: The outer sheath material affects the pipe’s corrosion resistance, moisture resistance, and mechanical protection.
Galvanized steel sheath: Suitable for high-temperature, long-distance underground pipelines, with excellent pressure and impact resistance.
Fiberglass reinforced plastic (FRP): Corrosion-resistant and suitable for chemical and humid environments.
PE sheath: Suitable for medium- and low-temperature underground hot water pipelines, but with limited heat resistance and mechanical strength.
When purchasing, consider the installation environment, temperature, and construction conditions when selecting the outer sheath.
iv. What are the types of pipe interfaces? Is it easy to install?
A: Common connection types include:
Welding and flanges.
Rock wool insulated steel pipes are prefabricated at the factory, requiring only connection and sealing on site, reducing construction time. The appropriate connection type can be selected based on the construction process.
v. What is the service life and maintenance of rock wool insulated steel pipe?
Under standard construction and normal operating conditions, rock wool insulated steel pipes generally have a lifespan of 30–50 years.
Regularly inspect the joints and outer casing for integrity.
Damage to the outer casing and sealant should be promptly repaired.
When purchasing, verify the supplier’s warranty period and maintenance recommendations to ensure long-term reliable operation.
