Triangular yoke plates, with the industry standard code YPL series, are core connecting hardware for overhead transmission lines and substation towers. They are mainly used for insulator parallel connection, split conductor stress connection, and multi-line guy wire combination fixation. Relying on a triangular balanced force structure, they are suitable for complex line conditions such as high voltage, icing, and angles. As a load-bearing component of the line, the material directly determines the tensile strength, outdoor service life, and line operation safety. Based on the national standard GB/T 2314 for power fittings, the commonly used triangular yoke plate base materials, anti-corrosion processes, category distinctions, and applicable scenarios are as follows:
Main Base Material Classification (Applicable to all network projects): Cast iron and ductile iron are strictly prohibited for power triangular yoke plates. These materials are extremely brittle, have very poor tensile strength, and are prone to breakage under stress, failing to meet the load-bearing acceptance standards for high and low voltage transmission lines. Currently, the industry only uses three base materials: carbon steel plate, low-alloy high-strength steel plate, and integrated forged steel.
1. Q235B Carbon Structural Steel (Standard General Purpose)
This is the most widely used material for 10kV and 35kV distribution networks, and 110kV and 220kV conventional inland transmission lines. It is compatible with YPL-7, YPL-10, YPL-12, YPL-16, YPL-20, and YPL-25 models for small and medium loads. The material has balanced toughness, is easy to cut and punch, and has a moderate cost. It meets the tensile load requirements of conventional lines in plains and inland areas without wind or icing. The processing method involves CNC cutting of steel plates and one-piece punching, resulting in a flat plate surface. It is suitable for conventional double-string and triple-string insulator combinations and installations, and is suitable for the construction of most rural and urban distribution lines.
2. Q355B Low-Alloy High-Strength Steel (Heavy-Duty Reinforced Version) This steel replaces the traditional, older Q345 steel and is specifically designed for high-voltage, heavy-duty lines. It is compatible with high-load triangular yoke plates such as YPL-30, YPL-40, and YPL-50, and is widely used in 500kV and 750kV high-voltage transmission lines, mountainous icing lines, and towers in windy areas. Compared to Q235B steel, its tensile strength and deformation resistance are increased by more than 40%. The thickened plate design makes it less prone to bending and deformation under pressure, and it can withstand the high tensile force of three-split conductors. Suitable for harsh outdoor conditions, it is the designated base material for high-voltage power grid projects.
3. Carbon One-Piece Forged Steel (Special Type for Ultra-Large Loads) This material is formed by high-temperature forging of a single steel billet, eliminating defects such as steel plate splicing and punching delamination. It boasts high overall density, superior impact resistance, and fracture resistance. It is primarily used in YPL-60 and YPL-80 ultra-large load triangular yoke plates, suitable for cross-river long-span towers, 1000kV ultra-high voltage lines, and heavy-duty guy wire convergence points. Its overall load-bearing capacity far exceeds that of plate yoke plates, exhibiting exceptional stability under extreme blizzards and strong winds. It is a high-end, custom-made heavy-duty material.
Low-voltage distribution networks and ordinary high-voltage flat lines: Q235B hot-dip galvanized triangular yoke plates are preferred; mountainous areas with strong winds and icing, and 500kV high-voltage lines: Q355B high-strength steel hot-dip galvanized triangular yoke plates are preferred; ultra-high voltage and cross-river ultra-large span towers: one-piece forged steel hot-dip galvanized triangular yoke plates are selected, with material matching based on requirements, balancing construction costs and long-term line operation safety.
