Technical Specifications for Wire Fence Manufacturing and Installation
Section 1: General Welding Quality Standards
In the production of mesh and structural components, welding must strictly adhere to current national standards to ensure mechanical integrity and corrosion resistance.
1. Classification and Evaluation of Welding Defects
Standard: GB/T 6417.1-2005 (Classification of geometric imperfections in metallic materials – Fusion welding).
Technical Note: Focus should be placed on preventing undercuts, burn-through, cold joints, and weld beads. Any crack-related defects are strictly prohibited as they compromise structural safety.
2. Mechanical Testing of Welded Joints
Hardness Testing: Conducted per GB/T 2654-2008 to evaluate the hardness gradient across the Heat Affected Zone (HAZ) and prevent brittle failure.
Impact Testing: Conducted per GB/T 2650-2022 (Charpy V-notch) to determine the toughness of welds in low-temperature environments—crucial for highway safety in cold regions.
Bend Testing: Conducted per GB/T 2653-2008 to verify the ductility of the weld face and root, ensuring the wire fence absorbs energy rather than snapping upon impact.
Section 2: Highway Guardrail & Fence Specific Standards
1. Highway Safety Facility Design
Standard: JTG D81-2017 (Specifications for Design of Highway Traffic Safety Facilities).
Expert Insight: This standard defines the crashworthiness levels (e.g., Grade B, A, SB) and the required installation height/offset for various road types.
2. Product Manufacturing & Anti-Corrosion
Fencing Series: GB/T 26941 (Covers Frame Mesh, Double-edge Wire Mesh, and Chain Link Fence).
Corrosion Protection:GB/T 18226-2015 (Technical Conditions of Anti-corrosion of Steel Components for Highway Traffic Engineering).
Hot-dip Galvanizing: Minimum coating mass of $450\text{–}600g/m^2$ depending on substrate thickness.
Plastic Coating (PVC/PE/Powder): Must achieve Level 0 adhesion with a uniform thickness.
Section 3: Flanges and Piping Connections (SC Conduit)
1. Flange Welding Specifications
Standard: GB/T 9119-2010 (Slip-on Plate Flanges).
Installation Procedure
Slip-on Flanges (SO): The pipe end should be inserted into the flange bore to a depth of approximately 1/3 of the flange thickness, followed by internal and external fillet welds.
Butt-weld Flanges (WN): The pipe and flange neck must be aligned with a root gap of $1\text{–}3\text{mm}$ for full penetration welding.
2. Electrical Metallic Conduit (SC Pipe)
- Definition: SC (Steel Conduit) denotes heavy-wall welded steel pipe for cable protection.
- Material Standard: GB/T 3091-2015 (Welded steel pipes for low pressure liquid delivery).
- Wall Thickness: For DN125 pipes, the standard nominal wall thickness is 4.5mm. Substandard pipes (e.g., 2.5mm) do not meet safety requirements for structural or pressurized applications.
Section 4: Industry Specifications for Double-Edge Wire Fencing
The following table represents the standard commercial specifications for high-quality double-edge wire fencing (1.8m x 3.0m):
| Item | Industry Standard Specifications | Tolerance/Requirement |
| Wire Diameter | 3.5mm (Pre-coat) / 4.0mm (Post-coat) | $\pm 0.05\text{mm}$ |
| Mesh Size | 90mm × 170mm | Flat surface, no warping |
| Line Post | $\phi 48 \times 1.5\text{mm} \times 2200\text{mm}$ | Embedment depth $\ge 300\text{mm}$ |
| Corrosion Res. | PVC Dipping / Powder Spray | Salt Spray Test $\ge 1000\text{h}$ |
Section 5: Welding Symbols (GB/T 324)
Accurate interpretation of symbols on technical drawings is mandatory:
- Peripheral Symbol (Circle): Indicates a weld that extends around the entire periphery of the joint (i.e., all-around weld).
- Tail Symbol: Used for process identification (e.g., “135” for MAG welding) or specific technical instructions. Avoid using non-standard numerical notations in formal documentation.
