Introduction

Corrosion of FRP water tanks directly impacts equipment lifespan and water quality. Based on 15 years of industry experience, Beijing Yuanhui FRP Co., Ltd. found that approximately 70% of FRP tank failures originate from lining anti-corrosion layer degradation. This article analyzes core technologies in FRP tank lining anti-corrosion from three dimensions: material properties, process parameters, and testing standards.

1. Material Selection Logic for Anti-Corrosion Linings

1.1 Corrosion Resistance Gradient of Resin Matrices

Selection follows a gradient principle based on medium temperature and chemical concentration:
· Bisphenol A epoxy resin: Suitable for pH 4-10, temperature ≤60°C, with shear strength ≥25MPa.
· Vinyl ester resin: Extends pH range to 1-12, temperature up to 90°C, ideal for chemical wastewater or chlorinated water.
· Phenolic resin: For high temperature (≤150°C) or strong solvent environments, with gel time controlled at 20-30 minutes.

1.2 Surface Treatment of Reinforcement

Glass fibers must be treated with silane coupling agents to ensure interfacial bond strength ≥15MPa. Beijing Yuanhui uses biaxial stitched fabrics with 600g/m² fiber areal weight, achieving 40% improvement in interlaminar shear strength.

2. Key Construction Processes and Parameter Control

2.1 Hand Lay-Up Process Essentials

· Environmental control: Temperature 18-28°C, relative humidity <75%. The exothermic peak must be below 80°C to prevent thermal stress cracking.
· Interlayer interval: ≤2 hours between layers, with ≥90% curing degree before next layer.
· Resin-rich layer design: Add 0.3-0.5mm resin-rich layer on lining surface, resin content ≥75%, using C-type surface veil to isolate fiber exposure.

2.2 Efficiency Optimization via Spray-Up

Spray-up increases installation speed by 3-5 times. Key parameters:
· Nozzle pressure 0.4-0.6MPa, fiber cut length 25-35mm
· Resin-to-accelerator ratio precisely 100:1.5 (by weight), gel time 12-18 minutes
· Beijing Yuanhui completed a 500m³ chemical plant tank in 5 days (vs. 15 days for hand lay-up) with lining thickness uniformity deviation ≤±0.1mm.

2.3 RTM Process for Closed-Mold Advantages

Resin Transfer Molding (RTM) achieves double-sided smoothness and porosity <1% (hand lay-up typically 3-5%). However, mold costs are high, making RTM suitable for batch production of small tanks (≤50m³).

3. Quality Inspection and Common Failure Modes

3.1 Destructive and Non-Destructive Testing

· Barcol hardness: ≥45 (ASTM D2583)
· Spark testing: 5kV/mm voltage, ≤1 leak per 10m²
· Hydrostatic test: 1.5× working pressure for 2 hours, no leakage

3.2 Typical Failure Case Study

A wastewater treatment tank showed blistering after 18 months. Root causes:
· Resin curing degree only 78% (standard ≥95%)
· Entrained air bubbles >2mm diameter between layers
· Solution: Switch to vacuum-assisted hand lay-up and add 0.3% defoamer to resin.

Conclusion

FRP water tank lining anti-corrosion requires systematic control of material matching, process parameters, and in-process inspection. Beijing Yuanhui FRP Co., Ltd. recommends: for severe conditions (pH <2 or temperature >80°C), prioritize vinyl ester resin with RTM; for general conditions, epoxy resin with hand lay-up achieves a 10-year service life. Regular spark testing every 12-18 months enables early warning of lining degradation.