Introduction

The modular assembly process of FRP water tanks utilizes standardized SMC molded panels that are bolted and sealed on site. This method eliminates transportation difficulties and long construction periods associated with welded tanks, making it ideal for high-rise building water supply, fire protection, and industrial cooling systems. Beijing Yuanhui FRP Co., Ltd. reduced on-site installation time to 5 working days for a 300m³ tank, achieving a panel utilization rate of 97.3%.

1. SMC Panel Production and Quality Control

1.1 Material Formulation and Molding Parameters

SMC sheet consists of unsaturated polyester resin, 25%-30% glass fiber, calcium carbonate filler, and low-shrink additives. Molding temperature is 145±5°C, pressure 15-20MPa, with holding time calculated as 1.2 minutes per mm of panel thickness. For a standard 1000×1000×15mm panel, holding time is 18 minutes, achieving a shrinkage rate below 0.05%.

1.2 Testing Standards

Beijing Yuanhui FRP Co., Ltd. follows internal standard Q/YH FRP 001-2023:

• Flexural strength ≥160MPa (per GB/T 1449)
• Barcol hardness ≥45 (per GB/T 3854)
• Water absorption ≤0.5% (24h, 23°C)
• Water resistance: no delamination after 72-hour boiling test

2. Modular Connection Design

2.1 Flange and Sealing Groove System

Each panel has a 35mm high, 20mm wide raised flange. Adjacent panels form a tongue-and-groove alignment. The sealing groove is trapezoidal (top 8mm, bottom 6mm, depth 5mm), housing an EPDM gasket with 30%-40% compression. Under 0.6MPa water pressure, leakage rate after 2,000 compression cycles is below 0.01L/h·m.

2.2 Stainless Steel Bolt Assembly

Bolts are 304 stainless steel M12×45mm with dual washers (rubber + metal). Torque is controlled at 70-80N·m. Beijing Yuanhui uses digital torque wrenches for verification, maintaining deviation within ±3N·m.

3. On-Site Assembly Process

3.1 Foundation Inspection and Base Panel Installation

Concrete base flatness ≤5mm/2m, embedded steel plate levelness ≤3mm. Base panels are installed from center outward, with stainless steel tie rods at 600mm spacing, fixed with M16 bolts.

3.2 Side and Roof Panel Installation

Side panels are installed "corners first, then middle." Verticality is checked with a level after each row (deviation ≤2mm per row). Roof panels are installed after the internal tie rod grid is completed (horizontal spacing 900mm, vertical spacing 1200mm, 304 stainless steel, diameter 12mm).

3.3 Sealing and Pressure Testing

After all bolts are tightened, a full water test is performed: water is filled in three stages with 4-hour intervals. Final stabilization for 24 hours requires water level drop ≤2mm. In a Jinan project, Beijing Yuanhui recorded only 1.8mm drop over 72 hours.

4. Common Issues and Optimization

4.1 Panel Warpage

Cause: uneven cooling or premature demolding. Solution: extend holding time to 1.2× theoretical value, use clamping fixture for cooling below 40°C. Beijing Yuanhui reduced warpage from 2.5mm/m to 0.8mm/m using IR temperature monitoring.

4.2 Joint Leakage

Cause: gasket aging or insufficient bolt torque. Solution: use EPDM+silicone composite gaskets (service life 5→10 years). Retorque bolts with digital wrench every 6 months.

Conclusion

Modular FRP tank assembly is mature, offering 18%-25% cost savings over stainless steel welded tanks in the 150-500m³ range. Beijing Yuanhui FRP Co., Ltd. has reduced rework rate to below 0.3% through optimized SMC formulation and process control. Future trends include larger panel sizes (e.g., 2000×1000mm) and smart torque monitoring systems to further shorten installation cycles.