What Is a Moisture Barrier Coil and Where Is It Used?
If you work in construction, industrial insulation, oil and gas, or HVAC in the UAE or wider GCC, there is a good chance you have come across the term "moisture barrier coil" — but what exactly is it, how does it work, and why does it matter so much in the Gulf's demanding operating environment?
In this guide, we explain everything you need to know: the structure of a moisture barrier aluminium coil, the two main types available (Polysurlyn and Polykraft), where they are most commonly used, and how to choose the right product for your project.
What Is a Moisture Barrier Aluminium Coil?
A moisture barrier aluminium coil — also called aluminium jacketing with a moisture barrier — is a composite material made of an aluminium sheet or coil with a protective film laminated to its inner surface. The laminated film acts as a vapour and moisture retarder, preventing water and humidity from penetrating through the metal jacket and reaching the insulation and pipe or vessel beneath.
The outer aluminium layer provides mechanical protection against physical damage, UV exposure, and corrosive atmospheres. The inner moisture barrier film does a separate but equally important job: it prevents galvanic corrosion and rust on the underside of the jacket where it contacts insulation materials, which can absorb and hold moisture over time.
Together, the two layers form a complete mechanical insulation jacketing system that is widely used across industrial and commercial applications throughout the UAE, GCC, and internationally.
Why Moisture Barriers Matter in the UAE Climate
The UAE's climate creates a particularly demanding environment for insulation systems. Coastal cities like Dubai, Abu Dhabi, Sharjah, and Umm Al Quwain experience high humidity levels for much of the year. Salt-laden marine air accelerates corrosion on unprotected metals. At the same time, extreme daytime temperatures cause significant thermal cycling on pipes and vessels — expansion and contraction that can, over time, work moisture into insulation systems if they are not properly sealed.
In industrial applications such as petrochemical plants, power stations, and cement facilities — all well-represented across the UAE and broader GCC — insulation systems can fail catastrophically if moisture is allowed to breach the jacket and compromise the underlying insulation. A moisture barrier aluminium coil addresses this risk directly, making it an essential material specification for engineers and procurement managers in these sectors.
The Two Main Types of Moisture Barrier: Polysurlyn and Polykraft
AISL supplies two types of moisture barrier aluminium jacketing, corresponding to the two industry-standard barrier films: Polysurlyn and Polykraft. Each has distinct characteristics that make it better suited to certain environments and applications.
Polysurlyn Moisture Barrier (PSMB)
Polysurlyn moisture barrier, commonly abbreviated as PSMB, is a three-layer composite film laminated to the aluminium sheet using a heat process. The three layers are:
A polyethylene layer — provides flexibility, toughness, and resistance to puncture and tearing during installation and service
An aluminium foil layer — this is the true vapour barrier, creating an essentially impermeable seal against water vapour transmission
A polysurlyn layer — a co-extruded film of polyethylene and aluminium that adds additional moisture resistance and structural durability
The resulting laminate has a total film thickness of 76 µm and delivers extremely low water vapour transmission rates, zero pinholes (because any pinholes in one layer are covered by the other layers), and strong abrasion resistance during installation on site. It works in both hot and cold applications, which makes it highly versatile across the wide range of temperatures encountered in UAE industrial environments.
Polysurlyn is generally regarded as the higher-performance option and is the preferred specification for demanding environments such as offshore and onshore petrochemical plants, power generation facilities, and cold-chain logistics infrastructure.
Polykraft Moisture Barrier
Polykraft is a simpler, two-layer composite consisting of a single thin layer of polyethylene film laminated to a layer of kraft paper. Like Polysurlyn, it is factory-applied by continuous lamination across the full width of the aluminium jacketing.
Polykraft offers solid anti-corrosion and anti-galvanic protection for the underside of the metal jacket and is widely used in commercial building applications, HVAC systems, and general pipe insulation where the operating conditions are less severe than in heavy industrial environments.
It is typically the more cost-effective option for projects where the full performance characteristics of Polysurlyn are not required by specification.
Where Is Moisture Barrier Aluminium Coil Used?
The applications for moisture barrier aluminium jacketing are broad, spanning industrial, commercial, and infrastructure sectors. Below are the most common uses in the UAE and GCC markets.
1. Pipeline Insulation in Oil, Gas, and Petrochemical Plants
This is the single largest application for moisture barrier aluminium jacketing in the GCC. Refineries, LNG facilities, petrochemical complexes, and gas processing plants — concentrated in Abu Dhabi, Sharjah, and across Saudi Arabia and Oman — use aluminium jacketing with Polysurlyn moisture barriers on their process piping systems. The jacket protects the underlying insulation from the combination of heat, humidity, and corrosive chemical atmospheres that are common in these environments.
2. HVAC Ductwork and Equipment Insulation
In large commercial buildings, hotels, hospitals, and shopping malls — all of which are abundant in the UAE — HVAC duct systems are insulated with materials that require an outer protective jacket. Moisture barrier aluminium jacketing prevents humidity from penetrating into duct insulation, maintains the thermal performance of the system, and provides a clean, durable outer surface. Anti-sweat coating variants are also available for cold duct applications where condensation is a risk.
3. Industrial Vessels, Tanks, and Storage Equipment
Large storage tanks, pressure vessels, and heat exchangers in industrial plants are frequently insulated and clad with aluminium jacketing. The moisture barrier film protects against the ingress of process moisture and atmospheric humidity, preventing corrosion under insulation (CUI) — one of the most costly and difficult-to-detect failure modes in industrial plant maintenance.
4. Power Plants and Utilities
Steam lines, turbine casings, boiler insulation, and other high-temperature equipment in power generation facilities require robust insulation systems that can withstand prolonged exposure to heat, condensation cycles, and mechanical vibration. Polysurlyn-backed aluminium jacketing is a standard specification in UAE and GCC power plant construction and maintenance.
5. Cement Plants and Heavy Industry
Cement plants involve extensive high-temperature process equipment — kilns, preheaters, coolers, and conveying systems — that require insulation. Aluminium jacketing with moisture barriers protects insulation blankets and boards in these abrasive, dusty environments where unprotected insulation would deteriorate rapidly.
6. Commercial and Residential Building Insulation
Beyond heavy industry, moisture barrier aluminium coils are used in the roof and wall insulation panels of commercial and residential buildings. Applied to the inner surface of metal building panels, the moisture barrier prevents condensation from forming within the insulation layer — a key consideration in the UAE's climate where the temperature difference between an air-conditioned interior and the hot exterior can drive significant moisture movement through building envelopes.
7. Refrigerated Transport and Cold Storage
The cold chain logistics sector — growing rapidly in the UAE as the country develops into a major regional food distribution and e-commerce hub — uses stucco embossed aluminium with moisture barriers extensively in refrigerated truck bodies and cold storage facility walls. The moisture barrier is essential in these applications because the temperature differential between the cold interior and the ambient exterior creates a strong condensation risk on unprotected metal surfaces.
Polysurlyn vs Polykraft: Which Should You Specify?
The right choice depends on your application environment and project specification requirements.
If your project specification calls for compliance with ASTM or other international insulation standards, or if the operating environment involves aggressive chemicals, high humidity, or extreme temperatures, Polysurlyn is generally the safer and more commonly required choice. For standard commercial building and HVAC applications, Polykraft offers a cost-effective and fully functional solution.
When in doubt, AISL's technical team can advise on the right specification for your application.
Why Source Moisture Barrier Aluminium Coils from AISL?
Arabian Iron and Steel LLC (AISL) is the leading manufacturer and supplier of moisture barrier aluminium coils — both Polysurlyn and Polykraft types — in the UAE and Gulf region. Operating from its facility in the New Industrial Area of Umm Al Quwain, AISL manufactures all moisture barrier jacketing to order, custom-cut to client requirements.
Key reasons UAE and GCC buyers choose AISL:
ISO-certified quality — ISO 9001 (quality), ISO 14001 (environment), and ISO 45001 (safety) certified manufacturing
SASO certified — products meet Saudi Arabia Standards Organisation requirements for export to KSA
Custom cut-to-length — coils and sheets supplied to your exact project dimensions
Full alloy and coating range — AA1060 through AA6061, with Polysurlyn or Polykraft barrier and external coat options including PE, Acrylic, PVDF, and Anti-Sweat
Wide delivery network — doorstep delivery across UAE, Oman, Saudi Arabia, Kuwait, Bahrain, Qatar, Jordan, Yemen, and Sri Lanka
On-time delivery — AISL follows all UAE government standards and logistics requirements to guarantee timely supply
AISL also manufactures stucco embossed aluminium coils and a full range of prepainted aluminium coils (PPAL) for customers who require both jacketing and prepainted sheet products from a single trusted supplier.
