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2026 New Standards: A Collection of Corrosion Protection Coating Requirements for W Beam Guardrails

Release time:

2026-02-01

The new national standard GB/T 18226-2025 Technical Requirements for Corrosion Protection of Steel Components in Highway Traffic Engineering will be officially implemented on March 1, 2026. It unifies the specifications for core indicators such as classification, thickness, adhesion amount, adhesive force and salt spray resistance of corrosion protection coatings commonly used for W beam guardrails. The accurate collection is as follows.

I. Core Standards and Scope of Application

Scope of application: Steel components such as plates, columns, anti-blocks, brackets and fasteners of W beam steel guardrails.

Core changes: Unified implementation in accordance with GB/T 18226-2025, with no separate provisions for corrosion protection requirements; the classification of components and coating indicators are more clear, and the zinc coating requirements for fasteners are raised.

II. Requirements for Commonly Used Corrosion Protection Coatings (Classified by Process)

(I) Hot-dip Galvanized Coating (Single Coating)

Component Type	Average Zinc Coating Adhesion Amount	Average Zinc Coating Thickness	Minimum Local Thickness	Adhesive Force	Salt Spray Resistance
Main components (guardrail plates, columns, anti-blocks, brackets, etc.)	≥600g/㎡	≥85μm	≥61μm	Cross-cut test: Grade 0	≥1000h, no red rust
Fasteners (bolts, nuts, etc.)	≥350g/㎡	≥49μm	≥35μm	Cross-cut test: Grade 0	≥500h, no red rust

(II) Hot-dip Galvanizing + Spraying Composite Coating

Component Type	Zinc Coating (Adhesion Amount/Thickness)	Spraying Coating Thickness	Adhesive Force	Salt Spray Resistance
Main components	≥275g/㎡ (≥39μm)	≥76μm	Cross-cut test: Grade 0	≥1500h, no red rust
Fasteners	≥350g/㎡ (≥49μm)	No specific requirement	Cross-cut test: Grade 0	≥1000h, no red rust

(III) Hot-dip Galvanizing + Dipping Composite Coating

Component Type	Zinc Coating (Adhesion Amount/Thickness)	Dipping Coating Thickness	Adhesive Force	Salt Spray Resistance
Main components	≥275g/㎡ (≥39μm)	≥250μm	Cross-cut test: Grade 0	≥2000h, no red rust
Fasteners	≥350g/㎡ (≥49μm)	No specific requirement	Cross-cut test: Grade 0	≥1000h, no red rust

(IV) Epoxy Zinc-based Composite Coating

Component Type	Epoxy Zinc-based Coating Thickness	Polyester Spraying Coating Thickness	Total Thickness	Adhesive Force	Salt Spray Resistance
Main components	36-56μm	70-90μm	≥106μm	Cross-cut test: Grade 0	≥2000h, no red rust
Fasteners	≥350g/㎡ (≥49μm)	No specific requirement	—	Cross-cut test: Grade 0	≥1000h, no red rust

III. Key General Requirements

Coating appearance: No defects such as missing plating, pinholes, air bubbles, cracks and peeling, with uniform and consistent color.

Thickness detection: A magnetic thickness gauge shall be used. 5 points shall be tested per 2 ㎡ for main components, and 10 pieces shall be randomly tested per batch for fasteners.

Adhesive force test: Cross-cut test method with a grid spacing of 1mm, and no coating peeling after tape stripping.

Salt spray resistance test: Implemented in accordance with GB/T 10125, with no red rust within the specified time.

Special requirements for composite coatings: The zinc coating and organic coating shall be well combined without delamination and blistering.

IV. Key Comparison Points between New and Old Standards

Component classification: The corrosion protection requirements for connecting parts such as anti-blocks and brackets are unified with those for main components, and no separate distinction is made any more.

Fasteners: The zinc coating adhesion amount is increased from 120g/㎡ to 350g/㎡, the thickness is increased from 17μm to 49μm, and the requirement for the thickness of the outer coating is cancelled.

Epoxy zinc-based: No longer classified by corrosion environment, unified to 36-56μm with fixed values.

Composite coatings: The thickness of the outer coating is only required for main components, and only the zinc coating of fasteners is required to meet the standard.

V. Application Scenario Suggestions

Coating Type	Applicable Environment	Service Life	Advantages
Hot-dip Galvanized Coating	Ordinary highways, inland areas	15-20 years	Low cost, mature technology
Hot-dip Galvanizing + Spraying Composite Coating	Municipal roads, landscape areas	20-25 years	Attractive appearance, good weather resistance
Hot-dip Galvanizing + Dipping Composite Coating	Coastal areas, high salt spray areas	25-30 years	Strong corrosion resistance
Epoxy Zinc-based Composite Coating	Heavy industrial areas, acid rain areas	More than 30 years	Environmental protection, excellent anti-corrosion performance

The above requirements are based on GB/T 18226-2025, which will be officially implemented on March 1, 2026. Production, procurement and acceptance shall be carried out in accordance with the new standards to ensure the corrosion protection quality and service life of W beam guardrails.

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