In short: The insulation core is chosen by operating temperature. Closed-cell PIR suits cold and cryogenic service (to about −196 °C) because it does not absorb moisture; rigid mineral wool serves high-temperature process service (to about +650 °C); fibreglass is used where specified. The standing-seam jacketing stays constant — only the core changes.
The single most important specification decision in tank insulation isn't the jacketing — it's the insulation core. The right core depends almost entirely on operating temperature. This page walks through the three cores Max Thermal Fabricators offers in the MaxFab Tank Panel System — closed-cell polyisocyanurate (PIR), rigid mineral wool, and fibreglass — and how to pick between them.
The Three Core Options at a Glance
Closed-Cell Polyisocyanurate (PIR)
Industry-typical operating range: approximately −196 °C to +150 °C. Closed-cell. Does not absorb moisture. K-value remains stable for decades. Used for cold and cryogenic service — including LNG, liquid nitrogen, refrigerated process media, and any below-ambient application.
Rigid Mineral Wool
Industry-typical operating range: ambient up to approximately +650 °C for industrial board products. Non-combustible. Made from molten rock or slag spun into fibres and bonded into rigid board. Used for hot and high-temperature process service.
High-Temperature Polyiso
Continuous service to +177 °C (350 °F), intermittent to +190 °C (375 °F), and low-temperature service to approximately −183 °C (−297 °F). ASTM C591-17, 97% closed-cell, Class 1 fire rating (ASTM E84). Bridges the gap between standard PIR and mineral wool for hot service. In Canada, fabricated into tank panels only by MaxFab — see the high-temperature polyiso tank panel.
Fibreglass
Industry-typical operating range varies by product. Used when the client's spec calls for it, or where mineral wool isn't required and PIR's temperature range isn't enough. Less common in the MaxFab system than the others, but supplied when specified.
Side by Side
| Insulation core | Continuous service range | Typical service | Key properties |
|---|---|---|---|
| Closed-cell polyisocyanurate (PIR) | −196 °C to +150 °C (−321 °F to +302 °F) | Cryogenic, LNG, cold and ambient service | Closed-cell — does not absorb moisture; K-value ≈ 0.022–0.027 W/(m·K), stable for decades |
| High-temperature polyiso | −183 °C to +177 °C (−297 °F to +350 °F); intermittent to +190 °C (+375 °F) | Hot service beyond standard PIR's range | ASTM C591-17; 97% closed-cell; Class 1 fire rating (ASTM E84); in Canada, fabricated into tank panels only by MaxFab |
| Rigid mineral wool | Ambient to approximately +650 °C (+1,200 °F) | High-temperature process service | Non-combustible; above ~450 °F the organic binder degrades but the fibre structure and thermal performance remain; K ≈ 0.035–0.045 W/(m·K) |
| Fibreglass | Varies by product specification | Where the client's spec calls for it | Supplied and laminated to spec |
Service ranges are industry-typical figures for each core material class; the rated range for your project is confirmed against the specific product datasheet at quoting.
How to Pick — Decision Framework
1. What is the operating temperature?
This is the determining question. The framework:
- Below ambient / cryogenic (down to −196 °C): Closed-cell PIR. Mineral wool and fibreglass should not be used in cold-service applications where moisture absorption can cause both insulation failure and substrate corrosion.
- Ambient to +150 °C: Either PIR or mineral wool can work; PIR is often preferred for its closed-cell moisture resistance and tighter K-value.
- +150 °C to +177 °C: High-temperature polyiso — continuous service to 350 °F (177 °C) with closed-cell moisture resistance, where standard PIR exceeds its rating but mineral wool's thicker build isn't wanted.
- +177 °C to +650 °C: Mineral wool. Both polyiso grades exceed their rated service temperature in this range.
- Above +650 °C: Specialty refractory products outside the standard MaxFab core options — contact us to scope.
2. Is moisture a concern?
Almost always yes for industrial outdoor tanks in Canada. Even with a sealed standing-seam envelope, the core selection matters for resilience. Closed-cell PIR cannot absorb moisture, so an envelope breach at any point in the asset's life does not compromise insulation performance long-term. Open-fibre cores can — though the MaxFab sealed double-lock standing-seam envelope is designed to keep moisture out in either case.
3. Is there a fire or NFPA requirement?
For tanks subject to NFPA-22 or similar fire-protection standards, mineral wool's non-combustible nature is a specification advantage. PIR is rated for the temperatures it serves, but mineral wool is the typical specification choice when fire performance of the core itself is the gating requirement.
4. What does the client spec call for?
Some procurement specifications name a specific core material — typically because of plant standards, prior asset experience, or a corporate insulation policy. We supply to spec.
K-Value and Why It Matters
K-value (thermal conductivity) is a material's ability to conduct heat. Lower K-value means better insulation per inch of thickness, which means thinner panels for a given heat-loss target. K-value drives both panel thickness specification and lifetime energy savings.
Typical K-values:
- Closed-cell PIR: approximately 0.022–0.027 W/(m·K) — among the lowest of any commercial insulation. Stable for decades because it does not absorb moisture.
- Rigid mineral wool board: approximately 0.035–0.045 W/(m·K) depending on density and temperature. Higher than PIR — meaning thicker panels for the same heat-loss target, but the trade-off is much higher temperature service.
- Fibreglass: approximately 0.030–0.045 W/(m·K) depending on density and product.
For projects where energy loss is the leading economic driver — heat-traced tanks, cryogenic vessels, high-Δt assets — K-value stability over the service life is the lifecycle differentiator. PIR holds its K-value indefinitely because the closed cells don't take in water. Open-fibre cores, even when properly jacketed, can drift if the envelope ever loses integrity.
What Else We Need to Pick the Right Core
For a project-specific recommendation, the input set we work from:
- Operating temperature range (min and max)
- Process media (some specs influence core selection)
- Indoor vs. outdoor installation
- Freeze-thaw exposure
- Any NFPA or fire-protection requirements
- Client / plant insulation specification (if applicable)
- Energy-loss budget or heat-loss target (if applicable)
Send what you have to office@maxfab.ca or call 1-780-717-2956. We will scope core selection, panel thickness, jacketing material and seam pattern as one coordinated proposal — and respond inside one business day.
One System, Three Cores
The MaxFab Tank Panel System uses the same outer construction across all three core options — pre-formed aluminum jacketing with a Surlyn moisture barrier heat-laminated to the interior, sealed by a mechanically folded double-lock standing seam. The core is selected to the application. This is what makes the system serviceable across the full operating temperature range that Canadian industry runs at, from cryogenic LNG storage to high-temperature process vessels.