How to Choose the Right Aluminized Silicon Steel Coating Weight: AS80 to AS300 Explained

One of the most frequent technical questions buyers and engineers ask when sourcing aluminized silicon steel sheet is: "Which coating weight do I need?" The answer depends on the severity of your operating environment, the required service life, and the application's mechanical demands. This guide explains the practical differences between AS80, AS120, AS240, and AS300 coating weights — and helps you select the right grade with confidence. As a factory holding exclusive ready stock across all four coating classes, MESCO is uniquely positioned to supply whichever grade your application demands, with delivery in as little as 3 days.

Understanding Coating Weight: What the Numbers Mean

The coating weight designation in aluminized silicon steel — expressed as AS80, AS120, AS240, AS300, and so on — refers to the total mass of the aluminum-silicon alloy coating on both surfaces of the steel sheet, measured in grams per square meter (g/m²). A higher number means a thicker total coating, more aluminum-silicon material per unit area, and consequently greater corrosion resistance and longer service life in aggressive environments.

Under ASTM A463/A463M Type 1 (the predominant standard for AS-coated steel), the coating weight represents the minimum total coating mass on a triple-spot average sample. Under EN 10346, similar designations apply with slightly different sampling methods. All MESCO production is dual-certified to ASTM A463 and EN 10346 where required.

AS80: Entry-Level Protection for Moderate Environments

AS80 (minimum 80 g/m² total coating) is the lightest standard aluminized silicon coating weight, and is appropriate for applications where heat resistance is the primary requirement and corrosion exposure is moderate. Typical applications include:

● Residential HVAC ductwork and air handling components

● Interior oven and range components, where the environment is dry and high-temperature

● Automotive heat shields in protected underbody locations

● Light industrial enclosures and housings operating up to 400°C

AS80 offers excellent thermal performance at the lowest coating cost, making it the preferred choice when budget is a priority and the service environment does not involve significant moisture, salt, or chemical exposure.

AS120: The Industry Workhorse for Exhaust and Appliance Applications

AS120 (minimum 120 g/m² total coating) is the most widely used coating weight in global aluminized silicon steel supply, and the grade for which MESCO maintains the largest ready-stock inventory in China — the only supplier to do so for DX53D+AS120. It provides a meaningful step up in corrosion resistance over AS80, without the cost premium of heavy-coat grades. Primary applications include:

● Automotive exhaust pipes, muffler bodies, and tailpipe assemblies

● Commercial kitchen equipment and industrial ovens

● Heat exchangers in residential and commercial HVAC systems

● Gas boiler flue components and hot water heater shells

● Catalytic converter housings and exhaust system brackets

For the vast majority of automotive exhaust and appliance OEM applications, AS120 represents the optimal balance of performance, formability, and cost. MESCO's 3,000+ ton inventory includes a comprehensive range of AS120 grades and thicknesses, with 3-day delivery available.

AS240: Heavy-Coat Protection for Outdoor and Industrial Environments

AS240 (minimum 240 g/m² total coating) represents a step change in corrosion protection. With more than twice the coating mass of AS120, AS240 is engineered for applications where long service life in aggressive outdoor or industrial environments is required. MESCO was the first manufacturer in China — and the first in the world — to bring AS240 to commercial production, and we maintain exclusive ready stock of this grade.

AS240 is the standard specification for industrial pipeline insulation jacketing, where the combination of outdoor weathering, moisture cycling, and chemical vapor exposure demands a coating system far beyond what AS80 or AS120 can provide. Salt spray test performance of AS240 exceeds 4,000 hours, equivalent to the corrosion protection of stainless steel jacketing at a fraction of the cost. Key applications:

● Oil and gas pipeline insulation jacketing (onshore and offshore)

● LNG facility insulation metal jackets

● Petrochemical plant piping and equipment insulation

● Industrial furnace and boiler exterior cladding

AS300: Ultra-Heavy Coat for the Most Demanding Environments

AS300 (minimum 300 g/m² total coating) is the highest standard coating weight in commercial production, and MESCO is the only company in the world to maintain ready stock inventory of this grade. AS300 is specified for the most severe corrosion environments — offshore marine, coastal refineries, chemical processing plants, and tropical industrial installations where standard insulation jacketing materials fail within a few years.

The additional coating mass compared to AS240 provides measurable improvements in salt fog performance, cut-edge protection, and long-term barrier integrity. For projects where a 20–30 year service life target is specified and replacement or maintenance access is difficult or costly, AS300 is the material of choice.

Coating Weight Selection Quick Reference

● AS80 — Dry, high-temperature, moderate corrosion risk. Ovens, HVAC interiors, heat shields.

● AS120 — Standard exhaust, appliance, HVAC. Most widely used grade. 3-day delivery from MESCO stock.

● AS240 — Outdoor industrial insulation jacketing. Pipeline projects. MESCO exclusive stock.

● AS300 — Severe marine / chemical environments. Ultra-long service life. MESCO exclusive stock.

Why Source All Four Grades from One Factory

Sourcing aluminized silicon steel across multiple coating weights from different suppliers introduces quality inconsistency, lead time uncertainty, and logistics complexity. MESCO's integrated factory and 3,000+ ton multi-grade inventory allows buyers to consolidate all coating weight requirements under a single supplier relationship — with consistent chemistry, consistent mill certification standards, and a single point of contact for technical support.

Whether your project requires a standard AS120 exhaust-grade coil or an exclusive AS300 insulation jacketing sheet, MESCO's factory can fulfill from ready stock with delivery in as little as 3 days. Our technical team is available to assist with grade selection, sample requests, and material test report review.

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  ✉  Email: mesco@mescogroup.com.cn      Web: www.mescogroup.com.cn

  Stock: 3,000+ tons ready · AS120 / AS240 / AS300 exclusive · Delivery in 3 days