What Is the Best Insulation Material for Chilled Pipes? A Professional Guide

When it comes to chilled water and refrigeration systems, choosing the right insulation material is critical. Proper insulation prevents condensation, reduces energy loss, and protects systems from corrosion under insulation (CUI).

Below is a clear, expert guide based on global engineering practice and ECOIN INSULATION’s export experience.

1. Key Requirements for Chilled Pipe Insulation

Chilled pipe insulation materials must meet several strict criteria:

• Closed-cell structure
• Low water vapor permeability
• Low thermal conductivity (k-value)
• Strong condensation resistance
• Durability & mold resistance
• Easy installation and long service life

2. Recommended Insulation Materials for Chilled Pipes

(1) Rubber Foam Insulation (Elastomeric Foam) — Most Common & Highly Recommended

Best for: HVAC chilled water lines, refrigeration lines, VRV/VRF systems.

Why it’s recommended:

• Closed-cell structure provides excellent condensation control
• Very low water vapor permeability
• Flexible, easy to install, suitable for elbows & valves
• Good fire performance when produced as Class 0 / Class 1
• Durable and resistant to mold and mildew

Typical standards: ASTM C534, BS 476, EN 14304
Common thickness: 13mm / 19mm / 25mm

Rubber foam is the most widely used solution globally for chilled pipe insulation due to its consistent performance and cost-effectiveness.

(2) Phenolic Foam Insulation (Rigid) — High Performance for Commercial Projects

Best for: Hospitals, airports, data centers, high-end commercial buildings.

Benefits:

• One of the lowest thermal conductivity values in the insulation industry
• Provides strong condensation control when paired with foil jacketing
• Lightweight but rigid, offering good mechanical strength

Common standards: BS 476, EN 14308

Phenolic foam is ideal when engineers require higher insulation performance.

(3) Polyurethane (PU) / Polyisocyanurate (PIR) — For low-temperature industrial systems

Best for: Industrial refrigeration, cold storage facilities, chemical plants.

Strengths:

• Very low k-value, excellent for sub-zero applications
• Good compressive strength
• Can be used with vapor-barrier jacketing for long-term durability

PU/PIR is less common in regular HVAC chilled water piping but preferred for industrial cold systems.

(4) Cellular Glass — High-end, CUI-resistant option

Best for: Petrochemical plants, LNG terminals, high-humidity or corrosive environments.

Advantages:

• 100% closed-cell inorganic material
• Absolutely zero water absorption
• Non-combustible
• Excellent for preventing CUI in chilled and cryogenic systems

Though more expensive, cellular glass delivers unmatched long-term stability.

3. Which Material Should You Choose?

Here is a simple summary:

For most building HVAC systems, rubber foam insulation remains the No.1 choice due to its ease of installation and strong anti-condensation properties.

3. Client-Shared Failure Case: Why Fiberglass Should Not Be Used on Chilled Pipes

One of our clients shared a valuable real-world failure case from their previous engineering project.
The contractor had used fiberglass pipe insulation on a chilled water system. Although fiberglass is suitable for high-temperature pipelines, it is not a closed-cell material, so it cannot stop water vapor penetration.

After only a few months of operation, the entire insulation system became:

• Fully saturated with moisture
• Water dripping heavily from the pipes
• Thermal performance completely lost
• Mold forming inside the insulation
• The fiberglass pipe sections eventually softened, collapsed, and broke

The client documented the incident with photos and videos for industry learning.

This case demonstrates why fiberglass is not recommended for chilled pipes, especially in humid climates.

4. If Fiberglass Must Be Used on Chilled Pipes (High-Temperature Systems Only)

In certain special cases—such as chilled water systems where operating temperature exceeds 150°C, or combined hot–cold pipelines—engineering teams may choose fiberglass because of its high thermal resistance.

If fiberglass pipe insulation must be used, the following critical enhancement is required:

✔ Apply a PE Film Over the Kraft Paper Side of the Aluminum Foil Facing

The reason:

• Fiberglass typically comes with aluminum foil + kraft paper
• Kraft paper is not waterproof
• For chilled applications, the material must be fully vapor-sealed
• PE film converts the kraft side into a true vapor barrier

Without the PE film, moisture will penetrate the insulation and cause failure—exactly as seen in the client’s case above.

This protective method is commonly used in high-temperature systems where fiberglass is required but condensation risk still exists.

5. ECOIN INSULATION’s Professional Recommendation

At ECOIN INSULATION, we recommend closed-cell rubber foam for chilled pipe applications. We supply elastomeric rubber foam that meets:

• ASTM C534 Grade 1
• EN 14304
• Low water vapor permeability (< 0.043 perms)
• Thermal conductivity as low as 0.035 W/m·K at 24°C
• Black or aluminum-foil-faced options

This combination ensures reliable condensation control and long-term durability.

With real-world project experience and global export cases, ECOIN INSULATION provides solutions designed to avoid the common failures seen in the industry.