What Are the Quality Inspection Standards for Prestressed Steel Wire?

Prestressed steel wire is a critical load-bearing component in construction projects. Its quality directly impacts the safety of the structure, so strict inspection standards must be adhered to. The prestressed steel wire produced by our factory is thoroughly inspected in accordance with GB/T 5223-2014, "Steel Wire for Prestressed Concrete" (the current national recommended standard), ensuring product performance and quality meet standards. Full traceability, from raw material procurement to finished product delivery, ensures risk-free procurement and worry-free construction. Specific inspection items and standards are as follows:

Ⅰ. Appearance Inspection

Our products undergo appearance inspection using specialized tools to eliminate surface defects that could affect safety:

- Surface Condition: The surface must be smooth and clean, free of cracks, folds, scars, indentations, rust, and other defects. Minor scratches are permitted, but their depth must not exceed 3% of the nominal wire diameter (and ≤ 0.2mm). Scratch depth must be verified using a thickness gauge with an accuracy of 0.01mm. This prevents potential hazards that could affect the life of the project and ensures that every piece of wire is ready for immediate use in construction.

- Surface morphology (spiral ribs/indented wire): Rib height and notch spacing are measured point by point using a dedicated caliper. Deviations are strictly controlled within ±10%, ensuring a perfect fit with your anchorage and precast components, eliminating rework costs caused by dimensional deviations during installation.

- Ovality: A micrometer is used to measure the same cross-section three times in multiple directions, taking the maximum value to ensure ovality is ≤4% of the nominal diameter. This ensures uniform stress distribution on the wire and avoids localized stress concentration that can cause fracture. This is particularly suitable for high-stress environments such as bridges and high-rise buildings.

II. Dimensional Inspection

During dimensional inspection, our factory focuses on controlling diameter deviation to ensure optimal compatibility between the wire and the component:

- Diameter deviation: For wires with a nominal diameter of 4.0-7.0mm, the tolerance for round wire is ±0.08mm, and for spiral ribbed/indented wire is ±0.10mm. This is determined by taking the average of multiple micrometer measurements. Whether it's precast beams for municipal roads or tensioned structures for water conservancy projects, we can meet your standardized construction requirements.

III. Core Performance Testing

Our factory's product performance testing is conducted using professional mechanical testing equipment. Core indicators must meet the following requirements:

- Tensile Strength (Rm): Low-relaxation steel wire grade 1860Mpa often achieves measured values exceeding 1880 MPa (standard ≥1860 MPa), while high-grade cold-drawn steel wire exceeds 1580 MPa (standard ≥1570 MPa). This provides enhanced long-term load-bearing capacity and greater reliability in handling extreme conditions such as bridge overloads and high-rise building settlements.

- Yield Strength (Rel): Low-relaxation steel wire grade 1570Mpa achieves measured values exceeding 1400 MPa (standard ≥1380 MPa), while grade 1860 achieves ≥1650 MPa (standard ≥1637 MPa). This reduces deformation under extreme loads, reducing subsequent maintenance costs.

- Elongation (A): Measured elongation at a gauge length of 200mm is ≥3.8% (standard ≥3.5%), and at a gauge length of 100mm is ≥5.2% (standard ≥5.0%). It is resistant to brittle fracture in low-temperature and vibration environments, making it particularly suitable for industrial buildings in northern cold regions or those subject to high-frequency vibration.

- Relaxation Performance: Low-relaxation steel wire has a relaxation rate of ≤2.2% after 1000 hours (standard ≤2.5%). This reduces stress loss after long-term use, preventing cracks in the structure due to stress decay and extending the project's service life by at least 10 years.

IV. Other Specialized Tests

We offer customized testing solutions to meet the unique requirements of different scenarios, ensuring our products are precisely matched to your project:

- Elastic Modulus: Measured values are consistently between 2.03-2.07×10⁵MPa (standard ±10%), with minimal fluctuation. This allows you to accurately calculate structural deformation and avoid construction adjustments caused by design deviations.

- Fatigue Performance: For major projects, we can upgrade to a 3 million cycle load test (standard 2 million) to ensure long-term durability under conditions like high-frequency vibration on bridges and wind-induced sway on high-rise buildings, minimizing potential maintenance risks.

- Galvanizing Coating Quality (Galvanized Steel Wire): Hot-dip galvanizing coating weight is measured to be ≥320g/m² (standard ≥300g/m²). In winding tests, we can reduce the mandrel diameter to 4 times the wire diameter (standard 5 times) upon request, without any flaking of the zinc coating. This provides enhanced corrosion resistance, making it particularly suitable for coastal, high-humidity water conservancy or port projects.

Our factory conducts comprehensive inspections of all of the aforementioned testing procedures, and all products shipped with test reports ensure that inferior products are not released into the market. Our products also support third-party re-inspections. If you require samples, detailed quotes, or technical solutions, please contact us by phone or email. We will provide professional services to help you mitigate procurement risks.