I. Overview: The Cornerstone of Reliable Connections

As an innovative movable dam, the safety and durability of the Shield Rubber Dam are highly dependent on the precise connection of its various components. Bolts, as the most critical mechanical connectors, directly affect the overall stability of the dam body when it endures immense water pressure, impact loads, and long-term operation. We strictly select Grade 8.8 high-strength bolts that comply with international standards (e.g., ISO 898-1) to safeguard the lifelong safety of every Shield Rubber Dam.

II. Detailed Explanation of Core Characteristics

Outstanding Mechanical Strength

• Interpretation of Strength Grade: "Grade 8.8" is the performance grade designation for bolts. The first digit "8" represents 1/100 of the nominal tensile strength (800 MPa), meaning the bolt’s tensile strength is not less than 800 MPa. The second digit "8" indicates the yield ratio (ratio of yield strength to tensile strength) is 0.8, so its yield strength is not less than 800 × 0.8 = 640 MPa.
• Engineering Significance: This means Grade 8.8 bolts possess extremely high tensile and shear resistance, ensuring:
  ① Withstanding High Water Pressure: When retaining water, the bolts firmly secure the shield plates to prevent loosening or deformation at the joints.
  ② Resisting Impact Loads: When facing floods or impacts from floating debris, they provide reliable ductile support to avoid brittle fracture.
  ③ Maintaining Preload: They can apply and sustain sufficient preload to keep the connecting surfaces tightly fitted, effectively preventing stress fatigue.

Comprehensive Anti-Corrosion Protection System

Bolts for Shield Rubber Dams are long-term exposed to humid environments, alternating dry-wet conditions, or even submerged in water. Anti-corrosion is crucial to ensuring their long service life. We provide multi-layered anti-corrosion solutions:

• Substrate Anti-Corrosion: High-quality alloy steel is preferred to ensure material uniformity and corrosion resistance potential from the source.
• Surface Treatment (Customized by Environment):
  ① Hot-Dip Galvanizing: The most commonly used high-efficiency anti-corrosion method. Bolts undergo processes such as pickling, fluxing, and immersion in molten zinc to form a thick, uniform zinc coating (usually ≥50μm). The zinc coating not only provides a physical barrier but also offers cathodic protection through the sacrificial anode effect—even if the coating has minor scratches, it can still continuously protect the substrate from corrosion.
  ② Dacromet/Galvanic: A zinc-based chromate coating technology with no hydrogen embrittlement risk. Its anti-corrosion performance is superior to ordinary galvanizing, with extremely high salt spray corrosion resistance (up to hundreds of hours or more), making it especially suitable for coastal areas or regions with high water salinity.
  ③ Epoxy Coating: Provides excellent chemical stability and wear resistance, suitable for harsh environments with special anti-corrosion requirements.

Strict Quality Control

From raw material warehousing to finished product delivery, each batch of bolts undergoes a rigorous quality inspection process, including:

• Dimensional accuracy testing
• Mechanical property testing (tensile strength, hardness)
• Coating thickness measurement

• Salt spray testing to ensure anti-corrosion performance meets standards

III. Core Advantages of Choosing Grade 8.8 Bolts

1. Safety and Reliability: The high mechanical performance of Grade 8.8 bolts is the primary guarantee for the structural safety of Shield Rubber Dams, fundamentally eliminating major risks caused by connector failure.
2. Long Durability: Professional anti-corrosion treatment significantly extends the service life of bolts, matching the Shield Rubber Dam system (usually designed for over 50 years of service) and reducing long-term maintenance costs.
3. Standardization and Versatility: As an internationally universal standard, Grade 8.8 bolts come in complete specifications, enabling convenient procurement and facilitating spare parts stockpiling and later maintenance replacement for projects.

4. Cost-Effectiveness: While ensuring top-tier performance, Grade 8.8 bolts offer excellent cost-efficiency. They avoid safety hazards caused by using low-grade bolts and cost waste from overusing high-grade bolts, achieving a perfect balance between safety and cost.

IV. Conclusion

In the Shield Rubber Dam—a vital water conservancy facility related to public safety and water resource management—no detail can be overlooked. We firmly believe that the strict selection of the core connector—Grade 8.8 high-strength anti-corrosion bolts—not only reflects our meticulous pursuit of project quality but also represents a solemn commitment to the long-term safety of customers and society. Like the "bones and muscles" of the dam body, they work silently yet remain indestructible.

Supplementary Notes on Technical Terminology

1. "气盾坝" (Shield Rubber Dam): A standard translation in water conservancy engineering, specifically referring to a new type of water-retaining structure supported by air pressure.
2. "屈强比" (Yield Ratio): A professional mechanical engineering term, defined as the ratio of a material’s yield strength to its tensile strength, critical for evaluating bolt ductility and load-bearing stability.
3. "达克罗/久美特" (Dacromet/Galvanic): Dacromet is an international generic name for zinc-aluminum flake coating; "久美特" (Geomet) is a well-known brand of such coatings, hence the combined translation to cover both generic and brand-specific references.
4. "盐雾试验" (Salt Spray Testing): A standard accelerated corrosion test method in materials science, used to verify the anti-corrosion performance of coatings, with results typically measured in hours.